[PATCH xf86-video-amdgpu 10/13] Push staged color properties when DPMS state toggles On

[Leo Li]

On 2018-05-16 01:10 PM, Michel Dänzer wrote:
> On 2018-05-03 08:31 PM, sunpeng.li at amd.com wrote:
>> From: "Leo (Sunpeng) Li" <sunpeng.li at amd.com>
>>
>> This will persist color management properties on a CRTC across DPMS
>> state changes.
>>
>> Signed-off-by: Leo (Sunpeng) Li <sunpeng.li at amd.com>
>> ---
>>   src/drmmode_display.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/src/drmmode_display.c b/src/drmmode_display.c
>> index 45c582c..06ae902 100644
>> --- a/src/drmmode_display.c
>> +++ b/src/drmmode_display.c
>> @@ -1294,6 +1294,7 @@ drmmode_do_crtc_dpms(xf86CrtcPtr crtc, int mode)
>>   	AMDGPUEntPtr pAMDGPUEnt = AMDGPUEntPriv(scrn);
>>   	CARD64 ust;
>>   	int ret;
>> +	int i;
>>   
>>   	if (drmmode_crtc->dpms_mode == DPMSModeOn && mode != DPMSModeOn) {
>>   		uint32_t seq;
>> @@ -1341,6 +1342,11 @@ drmmode_do_crtc_dpms(xf86CrtcPtr crtc, int mode)
>>   			drmmode_crtc->interpolated_vblanks += delta_seq;
>>   		}
>>   
>> +		for (i = 0; i < CM_NUM_PROPS; i++) {
>> +			if (i == CM_GAMMA_LUT_SIZE || i == CM_DEGAMMA_LUT_SIZE)
>> +				continue;
>> +			drmmode_crtc_push_cm_prop(crtc, i);
>> +		}
>>   	}
>>   	drmmode_crtc->dpms_mode = mode;
>>   }
>>
> 
> This and patch 11 smell like workarounds for a kernel issue. The kernel
> should preserve the property values regardless of DPMS state.
> 
> This probably explains something I just discovered: the legacy gamma LUT
> becomes ineffective after turning a CRTC off and on again with DC,
> whereas it's preserved without DC.
> 

That's indeed a kernel issue, will look into it. This patch can be
dropped once the kernel persists the properties across dpms.

In terms of Patch 11, which persists the properties across hotplugs, is
it even a valid use-case? I tested with i915 and amdgpu non-dc drivers.
Both don't seem to persist legacy gamma across hotplugs, or xrandr
--output --off/--auto. If not, patches 9-11 can all be dropped.

Leo

>