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From bc59d9d97142b3ecd7102adba9f17dca171d0411 Mon Sep 17 00:00:00 2001
From: David Francis <David.Francis@amd.com>
Date: Tue, 6 Nov 2018 11:06:04 -0500
Subject: [PATCH 0750/2940] drm/amd: Don't fail on backlight = 0
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>
---
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 9f13e65ed5f0..4f8dcde5dbe7 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1572,21 +1572,23 @@ 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
+ * 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;
--
2.17.1
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