drm/amd: Don't fail on backlight = 0 (694d0775) · Commits · 戴 / test

Amgpu's backlight update status function was returning 1 (an error value) when the backlight property was 0. This breaks users that assume 0 is a valid backlight value (which is a correct assumption) If the user passes in a backlight value of 0, tell them everything is fine, then write a value of 1 to hardware. Signed-off-by:

David Francis <David.Francis@amd.com> Bugzilla: https://bugs.freedesktop.org/108668 Fixes: 416615ea9578 ("drm/amd/display: set backlight level limit to 1") Cc: Suresh.Guttula@amd.com Cc: Harry.Wentland@amd.com Cc: Samantham@posteo.net Signed-off-by:

Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

+10 −8

Original line number	Diff line number	Diff line
		@@ -1573,21 +1573,23 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
		{
		struct amdgpu_display_manager *dm = bl_get_data(bd);

		/* backlight_pwm_u16_16 parameter is in unsigned 32 bit, 16 bit integer
		* and 16 bit fractional, where 1.0 is max backlight value.
		* bd->props.brightness is 8 bit format and needs to be converted by
		* scaling via copy lower byte to upper byte of 16 bit value.
		*/
		uint32_t brightness = bd->props.brightness * 0x101;

		/*
		* PWM interperts 0 as 100% rather than 0% because of HW
		* limitation for level 0. So limiting minimum brightness level
		* to 1.
		*/
		if (bd->props.brightness < 1)
		return 1;
		brightness = 0x101;

		/* backlight_pwm_u16_16 parameter is in unsigned 32 bit, 16 bit integer
		* and 16 bit fractional, where 1.0 is max backlight value.
		* bd->props.brightness is 8 bit format and needs to be converted by
		* scaling via copy lower byte to upper byte of 16 bit value.
		*/
		if (dc_link_set_backlight_level(dm->backlight_link,
		(bd->props.brightness * 0x101), 0, 0))
		brightness, 0, 0))
		return 0;
		else
		return 1;

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