On 2018-05-17 11:44 PM, Leo Li wrote:
> On 2018-05-16 01:10 PM, Michel Dänzer wrote:
>> On 2018-05-03 08:31 PM, sunpeng...@amd.com wrote:
>>> From: "Leo (Sunpeng) Li" <sunpeng...@amd.com>
>>>
>>> This will persist color management properties on a CRTC across DPMS
>>> state changes.
>>>
>>> Signed-off-by: Leo (Sunpeng) Li <sunpeng...@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.
It persists for me (without this series) with amdgpu without DC on
xrandr --output --off/--auto, or explicitly moving an output between
different CRTCs. Those are definitely expected.
Not sure about hotplug; it's possible that something explicitly
re-initializes the legacy gamma in that case. But other than that, each
CRTC should preserve its values unless they are explicitly modified.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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