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drm/amd: Don't fail on backlight = 0

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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>
This commit is contained in:
David Francis 2018-11-06 11:06:04 -05:00 committed by Alex Deucher
parent 45cf8c23f3
commit 694d0775ca
1 changed files with 11 additions and 9 deletions
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20
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
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@ -1573,21 +1573,23 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
{
struct amdgpu_display_manager *dm = bl_get_data(bd);
/*
* 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;
/* 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)
brightness = 0x101;
if (dc_link_set_backlight_level(dm->backlight_link,
(bd->props.brightness * 0x101), 0, 0))
brightness, 0, 0))
return 0;
else
return 1;