README

                                edge generates a key down event and a
                                rising edge generates a key up event.
                                When this is 0 (active high), this is
                                reversed. The default is 1 (active low).

        gpio_pull               Desired pull-up/down state (off, down, up)
                                Default is "up".

                                Note that the default pin (GPIO3) has an
                                external pullup. Same applies for GPIO1
                                on Raspberry Pi 1 Model B rev 1.

        debounce                Specify the debounce interval in milliseconds
                                (default 100)


Name:   hd44780-lcd
Info:   Configures an HD44780 compatible LCD display. Uses 4 gpio pins for
        data, 2 gpio pins for enable and register select and 1 optional pin
        for enabling/disabling the backlight display.
Load:   dtoverlay=hd44780-lcd,<param>=<val>
Params: pin_d4                  GPIO pin for data pin D4 (default 6)

        pin_d5                  GPIO pin for data pin D5 (default 13)

        pin_d6                  GPIO pin for data pin D6 (default 19)

        pin_d7                  GPIO pin for data pin D7 (default 26)

        pin_en                  GPIO pin for "Enable" (default 21)

        pin_rs                  GPIO pin for "Register Select" (default 20)

        pin_bl                  Optional pin for enabling/disabling the
                                display backlight. (default disabled)

        display_height          Height of the display in characters

        display_width           Width of the display in characters


Name:   hdmi-backlight-hwhack-gpio
Info:   Devicetree overlay for GPIO based backlight on/off capability.
        Use this if you have one of those HDMI displays whose backlight cannot
        be controlled via DPMS over HDMI and plan to do a little soldering to
        use an RPi gpio pin for on/off switching. See:
        https://www.waveshare.com/wiki/7inch_HDMI_LCD_(C)#Backlight_Control
Load:   dtoverlay=hdmi-backlight-hwhack-gpio,<param>=<val>
Params: gpio_pin                GPIO pin used (default 17)
        active_low              Set this to 1 if the display backlight is
                                switched on when the wire goes low.
                                Leave the default (value 0) if the backlight
                                expects a high to switch it on.


Name:   hifiberry-amp
Info:   Configures the HifiBerry Amp and Amp+ audio cards
Load:   dtoverlay=hifiberry-amp
Params: <None>


Name:   hifiberry-amp100
Info:   Configures the HifiBerry AMP100 audio card
Load:   dtoverlay=hifiberry-amp100,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=hifiberry-amp100,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24dB_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)
        slave                   Force DAC+ Pro into slave mode, using Pi as
                                master for bit clock and frame clock.
        leds_off                If set to 'true' the onboard indicator LEDs
                                are switched off at all times.
        auto_mute               If set to 'true' the amplifier is automatically
                                muted when the DAC is not playing.
        mute_ext_ctl            The amplifier's HW mute control is enabled
                                in ALSA mixer and set to <val>.
                                Will be overwritten by ALSA user settings.


Name:   hifiberry-dac
Info:   Configures the HifiBerry DAC audio cards
Load:   dtoverlay=hifiberry-dac
Params: <None>


Name:   hifiberry-dacplus
Info:   Configures the HifiBerry DAC+ audio card
Load:   dtoverlay=hifiberry-dacplus,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=hifiberry-dacplus,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24dB_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)
        slave                   Force DAC+ Pro into slave mode, using Pi as
                                master for bit clock and frame clock.
        leds_off                If set to 'true' the onboard indicator LEDs
                                are switched off at all times.


Name:   hifiberry-dacplusadc
Info:   Configures the HifiBerry DAC+ADC audio card
Load:   dtoverlay=hifiberry-dacplusadc,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=hifiberry-dacplus,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24dB_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)
        slave                   Force DAC+ Pro into slave mode, using Pi as
                                master for bit clock and frame clock.
        leds_off                If set to 'true' the onboard indicator LEDs
                                are switched off at all times.


Name:   hifiberry-dacplusadcpro
Info:   Configures the HifiBerry DAC+ADC PRO audio card
Load:   dtoverlay=hifiberry-dacplusadcpro,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=hifiberry-dacplusadcpro,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24dB_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)
        slave                   Force DAC+ADC Pro into slave mode, using Pi as
                                master for bit clock and frame clock.
        leds_off                If set to 'true' the onboard indicator LEDs
                                are switched off at all times.


Name:   hifiberry-dacplusdsp
Info:   Configures the HifiBerry DAC+DSP audio card
Load:   dtoverlay=hifiberry-dacplusdsp
Params: <None>


Name:   hifiberry-dacplushd
Info:   Configures the HifiBerry DAC+ HD audio card
Load:   dtoverlay=hifiberry-dacplushd
Params: <None>


Name:   hifiberry-digi
Info:   Configures the HifiBerry Digi and Digi+ audio card
Load:   dtoverlay=hifiberry-digi
Params: <None>


Name:   hifiberry-digi-pro
Info:   Configures the HifiBerry Digi+ Pro audio card
Load:   dtoverlay=hifiberry-digi-pro
Params: <None>


Name:   highperi
Info:   Enables "High Peripheral" mode
Load:   dtoverlay=highperi
Params: <None>


Name:   hy28a
Info:   HY28A - 2.8" TFT LCD Display Module by HAOYU Electronics
        Default values match Texy's display shield
Load:   dtoverlay=hy28a,<param>=<val>
Params: speed                   Display SPI bus speed

        rotate                  Display rotation {0,90,180,270}

        fps                     Delay between frame updates

        debug                   Debug output level {0-7}

        xohms                   Touchpanel sensitivity (X-plate resistance)

        resetgpio               GPIO used to reset controller

        ledgpio                 GPIO used to control backlight


Name:   hy28b
Info:   HY28B - 2.8" TFT LCD Display Module by HAOYU Electronics
        Default values match Texy's display shield
Load:   dtoverlay=hy28b,<param>=<val>
Params: speed                   Display SPI bus speed

        rotate                  Display rotation {0,90,180,270}

        fps                     Delay between frame updates

        debug                   Debug output level {0-7}

        xohms                   Touchpanel sensitivity (X-plate resistance)

        resetgpio               GPIO used to reset controller

        ledgpio                 GPIO used to control backlight


Name:   hy28b-2017
Info:   HY28B 2017 version - 2.8" TFT LCD Display Module by HAOYU Electronics
        Default values match Texy's display shield
Load:   dtoverlay=hy28b-2017,<param>=<val>
Params: speed                   Display SPI bus speed

        rotate                  Display rotation {0,90,180,270}

        fps                     Delay between frame updates

        debug                   Debug output level {0-7}

        xohms                   Touchpanel sensitivity (X-plate resistance)

        resetgpio               GPIO used to reset controller

        ledgpio                 GPIO used to control backlight


Name:   i-sabre-q2m
Info:   Configures the Audiophonics I-SABRE Q2M DAC
Load:   dtoverlay=i-sabre-q2m
Params: <None>


Name:   i2c-bcm2708
Info:   Fall back to the i2c_bcm2708 driver for the i2c_arm bus.
Load:   dtoverlay=i2c-bcm2708
Params: <None>


Name:   i2c-gpio
Info:   Adds support for software i2c controller on gpio pins
Load:   dtoverlay=i2c-gpio,<param>=<val>
Params: i2c_gpio_sda            GPIO used for I2C data (default "23")

        i2c_gpio_scl            GPIO used for I2C clock (default "24")

        i2c_gpio_delay_us       Clock delay in microseconds
                                (default "2" = ~100kHz)

        bus                     Set to a unique, non-zero value if wanting
                                multiple i2c-gpio busses. If set, will be used
                                as the preferred bus number (/dev/i2c-<n>). If
                                not set, the default value is 0, but the bus
                                number will be dynamically assigned - probably
                                3.


Name:   i2c-mux
Info:   Adds support for a number of I2C bus multiplexers on i2c_arm
Load:   dtoverlay=i2c-mux,<param>=<val>
Params: pca9542                 Select the NXP PCA9542 device

        pca9545                 Select the NXP PCA9545 device

        pca9548                 Select the NXP PCA9548 device

        addr                    Change I2C address of the device (default 0x70)


[ The i2c-mux-pca9548a overlay has been deleted. See i2c-mux. ]


Name:   i2c-pwm-pca9685a
Info:   Adds support for an NXP PCA9685A I2C PWM controller on i2c_arm
Load:   dtoverlay=i2c-pwm-pca9685a,<param>=<val>
Params: addr                    I2C address of PCA9685A (default 0x40)


Name:   i2c-rtc
Info:   Adds support for a number of I2C Real Time Clock devices
Load:   dtoverlay=i2c-rtc,<param>=<val>
Params: abx80x                  Select one of the ABx80x family:
                                  AB0801, AB0803, AB0804, AB0805,
                                  AB1801, AB1803, AB1804, AB1805

        ds1307                  Select the DS1307 device

        ds1339                  Select the DS1339 device

        ds3231                  Select the DS3231 device

        m41t62                  Select the M41T62 device

        mcp7940x                Select the MCP7940x device

        mcp7941x                Select the MCP7941x device

        pcf2127                 Select the PCF2127 device

        pcf2129                 Select the PCF2129 device

        pcf85063                Select the PCF85063 device

        pcf85063a               Select the PCF85063A device

        pcf8523                 Select the PCF8523 device

        pcf85363                Select the PCF85363 device

        pcf8563                 Select the PCF8563 device

        rv1805                  Select the Micro Crystal RV1805 device

        rv3028                  Select the Micro Crystal RV3028 device

        sd3078                  Select the ZXW Shenzhen whwave SD3078 device

        i2c0                    Choose the I2C0 bus on GPIOs 0&1

        i2c_csi_dsi             Choose the I2C0 bus on GPIOs 44&45

        addr                    Sets the address for the RTC. Note that the
                                device must be configured to use the specified
                                address.

        trickle-diode-type      Diode type for trickle charge - "standard" or
                                "schottky" (ABx80x and RV1805 only)

        trickle-resistor-ohms   Resistor value for trickle charge (DS1339,
                                ABx80x, RV1805, RV3028)

        wakeup-source           Specify that the RTC can be used as a wakeup
                                source

        backup-switchover-mode  Backup power supply switch mode. Must be 0 for
                                off or 1 for Vdd < VBackup (RV3028 only)


Name:   i2c-rtc-gpio
Info:   Adds support for a number of I2C Real Time Clock devices
        using the software i2c controller
Load:   dtoverlay=i2c-rtc-gpio,<param>=<val>
Params: abx80x                  Select one of the ABx80x family:
                                  AB0801, AB0803, AB0804, AB0805,
                                  AB1801, AB1803, AB1804, AB1805

        ds1307                  Select the DS1307 device

        ds1339                  Select the DS1339 device

        ds3231                  Select the DS3231 device

        m41t62                  Select the M41T62 device

        mcp7940x                Select the MCP7940x device

        mcp7941x                Select the MCP7941x device

        pcf2127                 Select the PCF2127 device

        pcf2129                 Select the PCF2129 device

        pcf8523                 Select the PCF8523 device

        pcf8563                 Select the PCF8563 device

        rv1805                  Select the Micro Crystal RV1805 device

        rv3028                  Select the Micro Crystal RV3028 device

        addr                    Sets the address for the RTC. Note that the
                                device must be configured to use the specified
                                address.

        trickle-diode-type      Diode type for trickle charge - "standard" or
                                "schottky" (ABx80x and RV1805 only)

        trickle-resistor-ohms   Resistor value for trickle charge (DS1339,
                                ABx80x, RV1805, RV3028)

        wakeup-source           Specify that the RTC can be used as a wakeup
                                source

        backup-switchover-mode  Backup power supply switch mode. Must be 0 for
                                off or 1 for Vdd < VBackup (RV3028 only)

        i2c_gpio_sda            GPIO used for I2C data (default "23")

        i2c_gpio_scl            GPIO used for I2C clock (default "24")

        i2c_gpio_delay_us       Clock delay in microseconds
                                (default "2" = ~100kHz)


Name:   i2c-sensor
Info:   Adds support for a number of I2C barometric pressure and temperature
        sensors on i2c_arm
Load:   dtoverlay=i2c-sensor,<param>=<val>
Params: addr                    Set the address for the BME280, BME680, BMP280,
                                DS1621, HDC100X, LM75, SHT3x or TMP102

        bme280                  Select the Bosch Sensortronic BME280
                                Valid addresses 0x76-0x77, default 0x76

        bme680                  Select the Bosch Sensortronic BME680
                                Valid addresses 0x76-0x77, default 0x76

        bmp085                  Select the Bosch Sensortronic BMP085

        bmp180                  Select the Bosch Sensortronic BMP180

        bmp280                  Select the Bosch Sensortronic BMP280
                                Valid addresses 0x76-0x77, default 0x76

        ds1621                  Select the Dallas Semiconductors DS1621 temp
                                sensor. Valid addresses 0x48-0x4f, default 0x48

        hdc100x                 Select the Texas Instruments HDC100x temp sensor
                                Valid addresses 0x40-0x43, default 0x40

        htu21                   Select the HTU21 temperature and humidity sensor

        lm75                    Select the Maxim LM75 temperature sensor
                                Valid addresses 0x48-0x4f, default 0x4f

        lm75addr                Deprecated - use addr parameter instead

        max17040                Select the Maxim Integrated MAX17040 battery
                                monitor

        sht3x                   Select the Sensiron SHT3x temperature and
                                humidity sensor. Valid addresses 0x44-0x45,
                                default 0x44

        si7020                  Select the Silicon Labs Si7013/20/21 humidity/
                                temperature sensor

        sps30                   Select the Sensirion SPS30 particulate matter
                                sensor. Fixed address 0x69.

        tmp102                  Select the Texas Instruments TMP102 temp sensor
                                Valid addresses 0x48-0x4b, default 0x48

        tsl4531                 Select the AMS TSL4531 digital ambient light
                                sensor

        veml6070                Select the Vishay VEML6070 ultraviolet light
                                sensor


Name:   i2c0
Info:   Change i2c0 pin usage. Not all pin combinations are usable on all
        platforms - platforms other then Compute Modules can only use this
        to disable transaction combining.
        Do NOT use in conjunction with dtparam=i2c_vc=on. From the 5.4 kernel
        onwards the base DT includes the use of i2c_mux_pinctrl to expose two
        muxings of BSC0 - GPIOs 0&1, and whichever combination is used for the
        camera and display connectors. This overlay disables that mux and
        configures /dev/i2c0 to point at whichever set of pins is requested.
        dtparam=i2c_vc=on will try and enable the mux, so combining the two
        will cause conflicts.
Load:   dtoverlay=i2c0,<param>=<val>
Params: pins_0_1                Use pins 0 and 1 (default)
        pins_28_29              Use pins 28 and 29
        pins_44_45              Use pins 44 and 45
        pins_46_47              Use pins 46 and 47
        combine                 Allow transactions to be combined (default
                                "yes")


Name:   i2c0-bcm2708
Info:   Deprecated, legacy version of i2c0.
Load:   <Deprecated>


Name:   i2c1
Info:   Change i2c1 pin usage. Not all pin combinations are usable on all
        platforms - platforms other then Compute Modules can only use this
        to disable transaction combining.
Load:   dtoverlay=i2c1,<param>=<val>
Params: pins_2_3                Use pins 2 and 3 (default)
        pins_44_45              Use pins 44 and 45
        combine                 Allow transactions to be combined (default
                                "yes")


Name:   i2c1-bcm2708
Info:   Deprecated, legacy version of i2c1.
Load:   <Deprecated>


Name:   i2c3
Info:   Enable the i2c3 bus. BCM2711 only.
Load:   dtoverlay=i2c3,<param>
Params: pins_2_3                Use GPIOs 2 and 3
        pins_4_5                Use GPIOs 4 and 5 (default)
        baudrate                Set the baudrate for the interface (default
                                "100000")


Name:   i2c4
Info:   Enable the i2c4 bus. BCM2711 only.
Load:   dtoverlay=i2c4,<param>
Params: pins_6_7                Use GPIOs 6 and 7
        pins_8_9                Use GPIOs 8 and 9 (default)
        baudrate                Set the baudrate for the interface (default
                                "100000")


Name:   i2c5
Info:   Enable the i2c5 bus. BCM2711 only.
Load:   dtoverlay=i2c5,<param>
Params: pins_10_11              Use GPIOs 10 and 11
        pins_12_13              Use GPIOs 12 and 13 (default)
        baudrate                Set the baudrate for the interface (default
                                "100000")


Name:   i2c6
Info:   Enable the i2c6 bus. BCM2711 only.
Load:   dtoverlay=i2c6,<param>
Params: pins_0_1                Use GPIOs 0 and 1
        pins_22_23              Use GPIOs 22 and 23 (default)
        baudrate                Set the baudrate for the interface (default
                                "100000")


Name:   i2s-gpio28-31
Info:   move I2S function block to GPIO 28 to 31
Load:   dtoverlay=i2s-gpio28-31
Params: <None>


Name:   ilitek251x
Info:   Enables I2C connected Ilitek 251x multiple touch controller using
        GPIO 4 (pin 7 on GPIO header) for interrupt.
Load:   dtoverlay=ilitek251x,<param>=<val>
Params: interrupt               GPIO used for interrupt (default 4)
        sizex                   Touchscreen size x, horizontal resolution of
                                touchscreen (in pixels)
        sizey                   Touchscreen size y, vertical resolution of
                                touchscreen (in pixels)


Name:   imx219
Info:   Sony IMX219 camera module.
        Uses Unicam 1, which is the standard camera connector on most Pi
        variants.
Load:   dtoverlay=imx219,<param>=<val>
Params: rotation                Mounting rotation of the camera sensor (0 or
                                180, default 180)


Name:   imx290
Info:   Sony IMX290 camera module.
        Uses Unicam 1, which is the standard camera connector on most Pi
        variants. NB This currently uses 4 CSI2 data lanes and therefore will
        only work on a CM.
Load:   dtoverlay=imx290,<param>
Params: 4lane                   Enable 4 CSI2 lanes. This requires a Compute
                                Module (1, 3, or 4).
        clock-frequency         Sets the clock frequency to match that used on
                                the board.
                                Modules from Vision Components use 37.125MHz
                                (the default), whilst those from Innomaker use
                                74.25MHz.
        mono                    Denote that the module is a mono sensor.


Name:   imx477
Info:   Sony IMX477 camera module.
        Uses Unicam 1, which is the standard camera connector on most Pi
        variants.
Load:   dtoverlay=imx477,<param>=<val>
Params: rotation                Mounting rotation of the camera sensor (0 or
                                180, default 180)


Name:   iqaudio-codec
Info:   Configures the IQaudio Codec audio card
Load:   dtoverlay=iqaudio-codec
Params: <None>


Name:   iqaudio-dac
Info:   Configures the IQaudio DAC audio card
Load:   dtoverlay=iqaudio-dac,<param>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=iqaudio-dac,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24db_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)


Name:   iqaudio-dacplus
Info:   Configures the IQaudio DAC+ audio card
Load:   dtoverlay=iqaudio-dacplus,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=iqaudio-dacplus,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24db_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)
        auto_mute_amp           If specified, unmute/mute the IQaudIO amp when
                                starting/stopping audio playback.
        unmute_amp              If specified, unmute the IQaudIO amp once when
                                the DAC driver module loads.


Name:   iqaudio-digi-wm8804-audio
Info:   Configures the IQAudIO Digi WM8804 audio card
Load:   dtoverlay=iqaudio-digi-wm8804-audio,<param>=<val>
Params: card_name               Override the default, "IQAudIODigi", card name.
        dai_name                Override the default, "IQAudIO Digi", dai name.
        dai_stream_name         Override the default, "IQAudIO Digi HiFi",
                                dai stream name.


Name:   irs1125
Info:   Infineon irs1125 TOF camera module.
        Uses Unicam 1, which is the standard camera connector on most Pi
        variants.
Load:   dtoverlay=irs1125
Params: <None>


Name:   jedec-spi-nor
Info:   Adds support for JEDEC-compliant SPI NOR flash devices.  (Note: The
        "jedec,spi-nor" kernel driver was formerly known as "m25p80".)
Load:   dtoverlay=jedec-spi-nor,<param>=<val>
Params: flash-spi<n>-<m>        Enables flash device on SPI<n>, CS#<m>.
        flash-fastr-spi<n>-<m>  Enables flash device with fast read capability
                                on SPI<n>, CS#<m>.


Name:   justboom-both
Info:   Simultaneous usage of an justboom-dac and justboom-digi based
        card
Load:   dtoverlay=justboom-both,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=justboom-dac,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24dB_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)


Name:   justboom-dac
Info:   Configures the JustBoom DAC HAT, Amp HAT, DAC Zero and Amp Zero audio
        cards
Load:   dtoverlay=justboom-dac,<param>=<val>
Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                Digital volume control. Enable with
                                "dtoverlay=justboom-dac,24db_digital_gain"
                                (The default behaviour is that the Digital
                                volume control is limited to a maximum of
                                0dB. ie. it can attenuate but not provide
                                gain. For most users, this will be desired
                                as it will prevent clipping. By appending
                                the 24dB_digital_gain parameter, the Digital
                                volume control will allow up to 24dB of
                                gain. If this parameter is enabled, it is the
                                responsibility of the user to ensure that
                                the Digital volume control is set to a value
                                that does not result in clipping/distortion!)


Name:   justboom-digi
Info:   Configures the JustBoom Digi HAT and Digi Zero audio cards
Load:   dtoverlay=justboom-digi
Params: <None>


Name:   lirc-rpi
Info:   This overlay has been deprecated and removed - see gpio-ir
Load:   <Deprecated>


Name:   ltc294x
Info:   Adds support for the ltc294x family of battery gauges
Load:   dtoverlay=ltc294x,<param>=<val>
Params: ltc2941                 Select the ltc2941 device

        ltc2942                 Select the ltc2942 device

        ltc2943                 Select the ltc2943 device

        ltc2944                 Select the ltc2944 device

        resistor-sense          The sense resistor value in milli-ohms.
                                Can be a 32-bit negative value when the battery
                                has been connected to the wrong end of the
                                resistor.

        prescaler-exponent      Range and accuracy of the gauge. The value is
                                programmed into the chip only if it differs
                                from the current setting.
                                For LTC2941 only:
                                - Default value is 128
                                - the exponent is in the range 0-7 (default 7)
                                See the datasheet for more information.


Name:   max98357a
Info:   Configures the Maxim MAX98357A I2S DAC
Load:   dtoverlay=max98357a,<param>=<val>
Params: no-sdmode               Driver does not manage the state of the DAC's
                                SD_MODE pin (i.e. chip is always on).
        sdmode-pin              integer, GPIO pin connected to the SD_MODE input
                                of the DAC (default GPIO4 if parameter omitted).


Name:   maxtherm
Info:   Configure a MAX6675, MAX31855 or MAX31856 thermocouple as an IIO device.

        For devices on spi1 or spi2, the interfaces should be enabled
        with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
        The overlay expects to disable the relevant spidev node, so also using
        e.g. cs0_spidev=off is unnecessary.

        Example:
        MAX31855 on /dev/spidev0.0
            dtoverlay=maxtherm,spi0-0,max31855
        MAX31856 using a type J thermocouple on /dev/spidev2.1
            dtoverlay=spi2-2cs
            dtoverlay=maxtherm,spi2-1,max31856,type_j

Load:   dtoverlay=maxtherm,<param>=<val>
Params: spi<n>-<m>              Configure device at spi<n>, cs<m>
                                (boolean, required)
        max6675                 Enable support for the MAX6675 (default)
        max31855                Enable support for the MAX31855
        max31855e               Enable support for the MAX31855E
        max31855j               Enable support for the MAX31855J
        max31855k               Enable support for the MAX31855K
        max31855n               Enable support for the MAX31855N
        max31855r               Enable support for the MAX31855R
        max31855s               Enable support for the MAX31855S
        max31855t               Enable support for the MAX31855T
        max31856                Enable support for the MAX31856 (with type K)
        type_b                  Select a type B sensor for max31856
        type_e                  Select a type E sensor for max31856
        type_j                  Select a type J sensor for max31856
        type_k                  Select a type K sensor for max31856
        type_n                  Select a type N sensor for max31856
        type_r                  Select a type R sensor for max31856
        type_s                  Select a type S sensor for max31856
        type_t                  Select a type T sensor for max31856


Name:   mbed-dac
Info:   Configures the mbed AudioCODEC (TLV320AIC23B)
Load:   dtoverlay=mbed-dac
Params: <None>


Name:   mcp23017
Info:   Configures the MCP23017 I2C GPIO expander
Load:   dtoverlay=mcp23017,<param>=<val>
Params: gpiopin                 Gpio pin connected to the INTA output of the
                                MCP23017 (default: 4)

        addr                    I2C address of the MCP23017 (default: 0x20)

        mcp23008                Configure an MCP23008 instead.
        noints                  Disable the interrupt GPIO line.


Name:   mcp23s17
Info:   Configures the MCP23S08/17 SPI GPIO expanders.
        If devices are present on SPI1 or SPI2, those interfaces must be enabled
        with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
        If interrupts are enabled for a device on a given CS# on a SPI bus, that
        device must be the only one present on that SPI bus/CS#.
Load:   dtoverlay=mcp23s17,<param>=<val>
Params: s08-spi<n>-<m>-present  4-bit integer, bitmap indicating MCP23S08
                                devices present on SPI<n>, CS#<m>

        s17-spi<n>-<m>-present  8-bit integer, bitmap indicating MCP23S17
                                devices present on SPI<n>, CS#<m>

        s08-spi<n>-<m>-int-gpio integer, enables interrupts on a single
                                MCP23S08 device on SPI<n>, CS#<m>, specifies
                                the GPIO pin to which INT output of MCP23S08
                                is connected.

        s17-spi<n>-<m>-int-gpio integer, enables mirrored interrupts on a
                                single MCP23S17 device on SPI<n>, CS#<m>,
                                specifies the GPIO pin to which either INTA
                                or INTB output of MCP23S17 is connected.


Name:   mcp2515-can0
Info:   Configures the MCP2515 CAN controller on spi0.0
Load:   dtoverlay=mcp2515-can0,<param>=<val>
Params: oscillator              Clock frequency for the CAN controller (Hz)

        spimaxfrequency         Maximum SPI frequence (Hz)

        interrupt               GPIO for interrupt signal


Name:   mcp2515-can1
Info:   Configures the MCP2515 CAN controller on spi0.1
Load:   dtoverlay=mcp2515-can1,<param>=<val>
Params: oscillator              Clock frequency for the CAN controller (Hz)

        spimaxfrequency         Maximum SPI frequence (Hz)

        interrupt               GPIO for interrupt signal


Name:   mcp251xfd
Info:   Configures the MCP251XFD CAN controller family
        For devices on spi1 or spi2, the interfaces should be enabled
        with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Load:   dtoverlay=mcp251xfd,<param>=<val>
Params: spi<n>-<m>              Configure device at spi<n>, cs<m>
                                (boolean, required)

        oscillator              Clock frequency for the CAN controller (Hz)

        speed                   Maximum SPI frequence (Hz)

        interrupt               GPIO for interrupt signal

        rx_interrupt            GPIO for RX interrupt signal (nINT1) (optional)

        xceiver_enable          GPIO for CAN transceiver enable (optional)

        xceiver_active_high     specifiy if CAN transceiver enable pin is
                                active high (optional, default: active low)


Name:   mcp3008
Info:   Configures MCP3008 A/D converters
        For devices on spi1 or spi2, the interfaces should be enabled
        with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Load:   dtoverlay=mcp3008,<param>[=<val>]
Params: spi<n>-<m>-present      boolean, configure device at spi<n>, cs<m>
        spi<n>-<m>-speed        integer, set the spi bus speed for this device


Name:   mcp3202
Info:   Configures MCP3202 A/D converters
        For devices on spi1 or spi2, the interfaces should be enabled
        with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Load:   dtoverlay=mcp3202,<param>[=<val>]
Params: spi<n>-<m>-present      boolean, configure device at spi<n>, cs<m>
        spi<n>-<m>-speed        integer, set the spi bus speed for this device


Name:   mcp342x
Info:   Overlay for activation of Microchip MCP3421-3428 ADCs over I2C
Load:   dtoverlay=mcp342x,<param>=<val>
Params: addr                    I2C bus address of device, for devices with
                                addresses that are configurable, e.g. by
                                hardware links (default=0x68)
        mcp3421                 The device is an MCP3421
        mcp3422                 The device is an MCP3422
        mcp3423                 The device is an MCP3423
        mcp3424                 The device is an MCP3424
        mcp3425                 The device is an MCP3425
        mcp3426                 The device is an MCP3426
        mcp3427                 The device is an MCP3427
        mcp3428                 The device is an MCP3428


Name:   media-center
Info:   Media Center HAT - 2.83" Touch Display + extras by Pi Supply
Load:   dtoverlay=media-center,<param>=<val>
Params: speed                   Display SPI bus speed
        rotate                  Display rotation {0,90,180,270}
        fps                     Delay between frame updates
        xohms                   Touchpanel sensitivity (X-plate resistance)
        swapxy                  Swap x and y axis
        backlight               Change backlight GPIO pin {e.g. 12, 18}
        gpio_out_pin            GPIO for output (default "17")
        gpio_in_pin             GPIO for input (default "18")
        gpio_in_pull            Pull up/down/off on the input pin
                                (default "down")
        sense                   Override the IR receive auto-detection logic:
                                 "0" = force active-high
                                 "1" = force active-low
                                 "-1" = use auto-detection
                                (default "-1")
        softcarrier             Turn the software carrier "on" or "off"
                                (default "on")
        invert                  "on" = invert the output pin (default "off")
        debug                   "on" = enable additional debug messages
                                (default "off")


Name:   merus-amp
Info:   Configures the merus-amp audio card
Load:   dtoverlay=merus-amp,<param>=<val>
Params: spioff                  Turn SPI bus off


Name:   midi-uart0
Info:   Configures UART0 (ttyAMA0) so that a requested 38.4kbaud actually gets
        31.25kbaud, the frequency required for MIDI
Load:   dtoverlay=midi-uart0
Params: <None>


Name:   midi-uart1
Info:   Configures UART1 (ttyS0) so that a requested 38.4kbaud actually gets
        31.25kbaud, the frequency required for MIDI
Load:   dtoverlay=midi-uart1
Params: <None>


Name:   miniuart-bt
Info:   Switch the onboard Bluetooth function on Pi 3B, 3B+, 3A+, 4B and Zero W
        to use the mini-UART (ttyS0) and restore UART0/ttyAMA0 over GPIOs 14 &
        15. Note that this may reduce the maximum usable baudrate.
        N.B. It is also necessary to edit /lib/systemd/system/hciuart.service
        and replace ttyAMA0 with ttyS0, unless using Raspbian or another
        distribution with udev rules that create /dev/serial0 and /dev/serial1,
        in which case use /dev/serial1 instead because it will always be
        correct. Furthermore, you must also set core_freq and core_freq_min to
        the same value in config.txt or the miniuart will not work.
Load:   dtoverlay=miniuart-bt,<param>=<val>
Params: krnbt                   Set to "on" to enable autoprobing of Bluetooth
                                driver without need of hciattach/btattach


Name:   mmc
Info:   Selects the bcm2835-mmc SD/MMC driver, optionally with overclock
Load:   dtoverlay=mmc,<param>=<val>
Params: overclock_50            Clock (in MHz) to use when the MMC framework
                                requests 50MHz


Name:   mpu6050
Info:   Overlay for i2c connected mpu6050 imu
Load:   dtoverlay=mpu6050,<param>=<val>
Params: interrupt               GPIO pin for interrupt (default 4)
        addr                    I2C address of the device (default 0x68)


Name:   mz61581
Info:   MZ61581 display by Tontec
Load:   dtoverlay=mz61581,<param>=<val>
Params: speed                   Display SPI bus speed

        rotate                  Display rotation {0,90,180,270}

        fps                     Delay between frame updates