README

                dtoverlay=tinylcd35,touch,touchgpio=3


Name:   tpm-slb9670
Info:   Enables support for Infineon SLB9670 Trusted Platform Module add-on
        boards, which can be used as a secure key storage and hwrng,
        available as "Iridium SLB9670" by Infineon and "LetsTrust TPM" by pi3g.
Load:   dtoverlay=tpm-slb9670
Params: <None>


Name:   uart0
Info:   Change the pin usage of uart0
Load:   dtoverlay=uart0,<param>=<val>
Params: txd0_pin                GPIO pin for TXD0 (14, 32 or 36 - default 14)

        rxd0_pin                GPIO pin for RXD0 (15, 33 or 37 - default 15)

        pin_func                Alternative pin function - 4(Alt0) for 14&15,
                                7(Alt3) for 32&33, 6(Alt2) for 36&37


Name:   uart1
Info:   Change the pin usage of uart1
Load:   dtoverlay=uart1,<param>=<val>
Params: txd1_pin                GPIO pin for TXD1 (14, 32 or 40 - default 14)

        rxd1_pin                GPIO pin for RXD1 (15, 33 or 41 - default 15)


Name:   uart2
Info:   Enable uart 2 on GPIOs 0-3. BCM2711 only.
Load:   dtoverlay=uart2,<param>
Params: ctsrts                  Enable CTS/RTS on GPIOs 2-3 (default off)


Name:   uart3
Info:   Enable uart 3 on GPIOs 4-7. BCM2711 only.
Load:   dtoverlay=uart3,<param>
Params: ctsrts                  Enable CTS/RTS on GPIOs 6-7 (default off)


Name:   uart4
Info:   Enable uart 4 on GPIOs 8-11. BCM2711 only.
Load:   dtoverlay=uart4,<param>
Params: ctsrts                  Enable CTS/RTS on GPIOs 10-11 (default off)


Name:   uart5
Info:   Enable uart 5 on GPIOs 12-15. BCM2711 only.
Load:   dtoverlay=uart5,<param>
Params: ctsrts                  Enable CTS/RTS on GPIOs 14-15 (default off)


Name:   udrc
Info:   Configures the NW Digital Radio UDRC Hat
Load:   dtoverlay=udrc,<param>=<val>
Params: alsaname                Name of the ALSA audio device (default "udrc")


Name:   upstream
Info:   Allow usage of downstream .dtb with upstream kernel. Comprises the
        vc4-kms-v3d and dwc2 overlays.
Load:   dtoverlay=upstream
Params: <None>


Name:   upstream-aux-interrupt
Info:   This overlay has been deprecated and removed because it is no longer
        necessary.
Load:   <Deprecated>


Name:   upstream-pi4
Info:   Allow usage of downstream .dtb with upstream kernel on Pi 4. Comprises
        the vc4-kms-v3d-pi4 and dwc2 overlays.
Load:   dtoverlay=upstream-pi4
Params: <None>


Name:   vc4-fkms-v3d
Info:   Enable Eric Anholt's DRM VC4 V3D driver on top of the dispmanx
        display stack.
Load:   dtoverlay=vc4-fkms-v3d,<param>
Params: cma-512                 CMA is 512MB (needs 1GB)
        cma-448                 CMA is 448MB (needs 1GB)
        cma-384                 CMA is 384MB (needs 1GB)
        cma-320                 CMA is 320MB (needs 1GB)
        cma-256                 CMA is 256MB (needs 1GB)
        cma-192                 CMA is 192MB (needs 1GB)
        cma-128                 CMA is 128MB
        cma-96                  CMA is 96MB
        cma-64                  CMA is 64MB
        cma-size                CMA size in bytes, 4MB aligned
        cma-default             Use upstream's default value


Name:   vc4-kms-dsi-7inch
Info:   Enable the Raspberry Pi DSI 7" screen.
        Use edt-ft5406 for the touchscreen element.
        Requires vc4-kms-v3d to be loaded.
Load:   dtoverlay=vc4-kms-dsi-7inch
Params: <None>


Name:   vc4-kms-kippah-7inch
Info:   Enable the Adafruit DPI Kippah with the 7" Ontat panel attached.
        Requires vc4-kms-v3d to be loaded.
Load:   dtoverlay=vc4-kms-kippah-7inch
Params: <None>


Name:   vc4-kms-v3d
Info:   Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver.
Load:   dtoverlay=vc4-kms-v3d,<param>
Params: cma-512                 CMA is 512MB (needs 1GB)
        cma-448                 CMA is 448MB (needs 1GB)
        cma-384                 CMA is 384MB (needs 1GB)
        cma-320                 CMA is 320MB (needs 1GB)
        cma-256                 CMA is 256MB (needs 1GB)
        cma-192                 CMA is 192MB (needs 1GB)
        cma-128                 CMA is 128MB
        cma-96                  CMA is 96MB
        cma-64                  CMA is 64MB
        cma-size                CMA size in bytes, 4MB aligned
        cma-default             Use upstream's default value
        audio                   Enable or disable audio over HDMI (default "on")
        noaudio                 Disable all HDMI audio (default "off")
        nocomposite             Disable the composite video output (default
                                "off")


Name:   vc4-kms-v3d-pi4
Info:   Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver for Pi4.
Load:   dtoverlay=vc4-kms-v3d-pi4,<param>
Params: cma-512                 CMA is 512MB
        cma-448                 CMA is 448MB
        cma-384                 CMA is 384MB
        cma-320                 CMA is 320MB
        cma-256                 CMA is 256MB
        cma-192                 CMA is 192MB
        cma-128                 CMA is 128MB
        cma-96                  CMA is 96MB
        cma-64                  CMA is 64MB
        cma-size                CMA size in bytes, 4MB aligned
        cma-default             Use upstream's default value
        audio                   Enable or disable audio over HDMI0 (default
                                "on")
        audio1                  Enable or disable audio over HDMI1 (default
                                "on")
        noaudio                 Disable all HDMI audio (default "off")
        composite               Enable the composite output (disables all other
                                outputs)


Name:   vc4-kms-vga666
Info:   Enable the VGA666 (resistor ladder ADC) for the vc4-kms-v3d driver.
        Requires vc4-kms-v3d to be loaded.
Load:   dtoverlay=vc4-kms-vga666,<param>
Params: ddc                     Enables GPIOs 0&1 as the I2C to read the EDID
                                from the display. NB These are NOT 5V tolerant
                                GPIOs, therefore level shifters are required.


Name:   vga666
Info:   Overlay for the Fen Logic VGA666 board
        This uses GPIOs 2-21 (so no I2C), and activates the output 2-3 seconds
        after the kernel has started.
        NOT for use with vc4-kms-v3d.
Load:   dtoverlay=vga666
Params: <None>


Name:   w1-gpio
Info:   Configures the w1-gpio Onewire interface module.
        Use this overlay if you *don't* need a GPIO to drive an external pullup.
Load:   dtoverlay=w1-gpio,<param>=<val>
Params: gpiopin                 GPIO for I/O (default "4")
        pullup                  Now enabled by default (ignored)


Name:   w1-gpio-pullup
Info:   Configures the w1-gpio Onewire interface module.
        Use this overlay if you *do* need a GPIO to drive an external pullup.
Load:   dtoverlay=w1-gpio-pullup,<param>=<val>
Params: gpiopin                 GPIO for I/O (default "4")
        extpullup               GPIO for external pullup (default "5")
        pullup                  Now enabled by default (ignored)


Name:   w5500
Info:   Overlay for the Wiznet W5500 Ethernet Controller on SPI0
Load:   dtoverlay=w5500,<param>=<val>
Params: int_pin                 GPIO used for INT (default 25)

        speed                   SPI bus speed (default 30000000)

        cs                      SPI bus Chip Select (default 0)


Name:   wittypi
Info:   Configures the wittypi RTC module.
Load:   dtoverlay=wittypi,<param>=<val>
Params: led_gpio                GPIO for LED (default "17")
        led_trigger             Choose which activity the LED tracks (default
                                "default-on")


Name:   wm8960-soundcard
Info:   Overlay for the Waveshare wm8960 soundcard
Load:   dtoverlay=wm8960-soundcard,<param>=<val>
Params: alsaname                Changes the card name in ALSA
        compatible              Changes the codec compatibility


Troubleshooting
===============

If you are experiencing problems that you think are DT-related, enable DT
diagnostic output by adding this to /boot/config.txt:

    dtdebug=on

and rebooting. Then run:

    sudo vcdbg log msg

and look for relevant messages.

Further reading
===============

This is only meant to be a quick introduction to the subject of Device Tree on
Raspberry Pi. There is a more complete explanation here:

http://www.raspberrypi.org/documentation/configuration/device-tree.md