[PATCH] drm/i915: Fix legacy gamma lut updates in Linux 4.7-rc6

[Lionel Landwerlin]

On 12/07/16 13:11, Mario Kleiner wrote:
> On 07/12/2016 12:50 PM, Lionel Landwerlin wrote:
>> Hi Mario,
>>
>
> Hi Lionel,
>
>> There was a couple of patch to fix this issue :
>>
>> https://patchwork.freedesktop.org/series/5467/
>> https://patchwork.freedesktop.org/series/5466/
>>
>
> Looking at them they should fix the issue, but they seem to be stuck 
> in review?
>
>> I tested this late last week on drm-intel-nightly, it seems a series of
>> revert fixed most of the issues.
>>
>
> You mean something else has fixed legacy gamma updates, as i can't 
> find above patches applied on drm-intel-nightly?

This revert on drm-intel-nightly seems to have fixed the problem :

https://cgit.freedesktop.org/drm-intel/commit/drivers/gpu/drm/i915?id=e42aeef1237b7c969a77b7f726c50f6cb832185f

>
> Are those fixes supposed to be already part of 4.7-rc7, the final rc 
> afaik?

I haven't seen it on 4.7-rc7.

>
> thanks,
> -mario
>
>
>> Cheers,
>>
>> -
>> Lionel
>>
>> On 12/07/16 11:33, Mario Kleiner wrote:
>>> Updating legacy gamma tables, e.g., via RandR doesn't work at all
>>> as of Linux 4.7-rc6.
>>>
>>> Reason seems to be that the required call to
>>> drm_atomic_helper_commit_planes_on_crtc is skipped in
>>> intel_atomic_commit after userspace set new gamma tables,
>>> because neither crtc->state->planes_changed nor
>>> update_pipe (= pipe_config->update_pipe) are true.
>>>
>>> Removing the check for planes_changed || update_pipe fixes
>>> gamma table updates.
>>>
>>> The code for Linux 4.8 drm-next has changed a lot in that area
>>> wrt. 4.7, but the new code for 4.8 also removed those checks
>>> and calls drm_atomic_helper_commit_planes_on_crtc unconditionally,
>>> and legacy gamma lut updates work on drm-next, so this seems to be
>>> the right solution.
>>>
>>> Tested also shutdown/reboot, suspend/resume, (un-)plugging displays,
>>> mode switches for resolution/refresh rate, display rotation, and
>>> page-flipping/pageflip timing on Intel HD Ironlake to confirm the
>>> fix apparently doesn't break anything under X11.
>>>
>>> Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
>>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>> Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>>> ---
>>>   drivers/gpu/drm/i915/intel_display.c | 4 +---
>>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_display.c
>>> b/drivers/gpu/drm/i915/intel_display.c
>>> index 04452cf..eb8fb36 100644
>>> --- a/drivers/gpu/drm/i915/intel_display.c
>>> +++ b/drivers/gpu/drm/i915/intel_display.c
>>> @@ -13685,7 +13685,6 @@ static int intel_atomic_commit(struct
>>> drm_device *dev,
>>>           bool modeset = needs_modeset(crtc->state);
>>>           struct intel_crtc_state *pipe_config =
>>>               to_intel_crtc_state(crtc->state);
>>> -        bool update_pipe = !modeset && pipe_config->update_pipe;
>>>           if (modeset && crtc->state->active) {
>>>               update_scanline_offset(to_intel_crtc(crtc));
>>> @@ -13699,8 +13698,7 @@ static int intel_atomic_commit(struct
>>> drm_device *dev,
>>>               drm_atomic_get_existing_plane_state(state, 
>>> crtc->primary))
>>>               intel_fbc_enable(intel_crtc);
>>> -        if (crtc->state->active &&
>>> -            (crtc->state->planes_changed || update_pipe))
>>> +        if (crtc->state->active)
>>> drm_atomic_helper_commit_planes_on_crtc(old_crtc_state);
>>>           if (pipe_config->base.active && 
>>> needs_vblank_wait(pipe_config))
>>
>>
>