From 262485a50fd4532a8d71165190adc7a0a19bcc9e Mon Sep 17 00:00:00 2001 From: Anthony Koo Date: Fri, 12 Oct 2018 21:34:32 -0400 Subject: drm/amd/display: Expand dc to use 16.16 bit backlight [Why] We want to increase precision for backlight setting. But DC interface takes 8 bit backlight level value only. [How] DMCU already takes 16 bit backlight level. Expand the DC interface to take 16.16 bit value. Max 32 bit backlight value (0xFFFF) will represent max backlight (100%) Signed-off-by: Anthony Koo Reviewed-by: Tony Cheng Acked-by: Leo Li Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c') 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 a3849e161593..67b547c64a3e 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -1580,8 +1580,14 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd) */ 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. + */ if (dc_link_set_backlight_level(dm->backlight_link, - bd->props.brightness, 0, 0)) + (bd->props.brightness * 0x101), 0, 0)) return 0; else return 1; -- cgit v1.2.3