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

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Message-ID: <5784DE7B.4030407@gmail.com>
Date:	Tue, 12 Jul 2016 14:11:39 +0200
From:	Mario Kleiner <mario.kleiner.de@...il.com>
To:	Lionel Landwerlin <lionel.g.landwerlin@...el.com>,
	dri-devel@...ts.freedesktop.org
Cc:	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Subject: Re: [PATCH] drm/i915: Fix legacy gamma lut updates in Linux 4.7-rc6

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?

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

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@...il.com>
>> Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
>> Cc: Lionel Landwerlin <lionel.g.landwerlin@...el.com>
>> Cc: Daniel Vetter <daniel.vetter@...ll.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))
>
>