Commit d381baad authored by José Roberto de Souza's avatar José Roberto de Souza
Browse files

drm/i915/vbt: Fix backlight parsing for VBT 234+ 



Child min_brightness is obsolete from VBT 234+, instead the new
min_brightness field in the main structure should be used.

This new field is 16 bits wide, so backlight_precision_bits is needed
to check if value needs to be scaled down but it is only available in
VBT 236+ so working around it by using the also new backlight_level
in the main struct.

v2:
- missed that backlight_data->level is also obsolete

v3:
- s/backlight/brightness to better match specification
- using u16 to specify brightness level instead of a u32 : 16

BSpec: 20149
Reviewed-by: default avatarMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: default avatarJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201008211932.24989-1-jose.souza@intel.com
parent 63b9d9aa

drivers/gpu/drm/i915/display/intel_bios.c

+28 −2
Original line number Diff line number Diff line
@@ -425,6 +425,7 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, 
	const struct bdb_lfp_backlight_data *backlight_data;

	const struct lfp_backlight_data_entry *entry;

	int panel_type = dev_priv->vbt.panel_type;

	u16 level;



	backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);

	if (!backlight_data)
@@ -459,14 +460,39 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, 


	dev_priv->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz;

	dev_priv->vbt.backlight.active_low_pwm = entry->active_low_pwm;



	if (bdb->version >= 234) {

		u16 min_level;

		bool scale;



		level = backlight_data->brightness_level[panel_type].level;

		min_level = backlight_data->brightness_min_level[panel_type].level;



		if (bdb->version >= 236)

			scale = backlight_data->brightness_precision_bits[panel_type] == 16;

		else

			scale = level > 255;



		if (scale)

			min_level = min_level / 255;



		if (min_level > 255) {

			drm_warn(&dev_priv->drm, "Brightness min level > 255\n");

			level = 255;

		}

		dev_priv->vbt.backlight.min_brightness = min_level;

	} else {

		level = backlight_data->level[panel_type];

		dev_priv->vbt.backlight.min_brightness = entry->min_brightness;

	}



	drm_dbg_kms(&dev_priv->drm,

		    "VBT backlight PWM modulation frequency %u Hz, "

		    "active %s, min brightness %u, level %u, controller %u\n",

		    dev_priv->vbt.backlight.pwm_freq_hz,

		    dev_priv->vbt.backlight.active_low_pwm ? "low" : "high",

		    dev_priv->vbt.backlight.min_brightness,

		    backlight_data->level[panel_type],

		    level,

		    dev_priv->vbt.backlight.controller);

}

drivers/gpu/drm/i915/display/intel_vbt_defs.h

+10 −2
Original line number Diff line number Diff line
@@ -782,7 +782,7 @@ struct lfp_backlight_data_entry { 
	u8 active_low_pwm:1;

	u8 obsolete1:5;

	u16 pwm_freq_hz;

	u8 min_brightness;

	u8 min_brightness; /* Obsolete from 234+ */

	u8 obsolete2;

	u8 obsolete3;

} __packed;
@@ -792,11 +792,19 @@ struct lfp_backlight_control_method { 
	u8 controller:4;

} __packed;



struct lfp_brightness_level {

	u16 level;

	u16 reserved;

} __packed;



struct bdb_lfp_backlight_data {

	u8 entry_size;

	struct lfp_backlight_data_entry data[16];

	u8 level[16];

	u8 level[16]; /* Obsolete from 234+ */

	struct lfp_backlight_control_method backlight_control[16];

	struct lfp_brightness_level brightness_level[16];		/* 234+ */

	struct lfp_brightness_level brightness_min_level[16];	/* 234+ */

	u8 brightness_precision_bits[16];						/* 236+ */

} __packed;



/*