linux-kernel - Re: [PATCH] drm/tilcdc: send vblank event when disabling crtc

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Message-ID: <29f8d014-ddb5-527e-70eb-eab1079562dc@windriver.com>
Date:   Tue, 9 Feb 2021 16:07:11 +0800
From:   "quanyang.wang" <quanyang.wang@...driver.com>
To:     Jyri Sarha <jyri.sarha@....fi>
Cc:     Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/tilcdc: send vblank event when disabling crtc

Hi Jyri,

On 2/9/21 3:58 PM, Jyri Sarha wrote:
> On 2021-02-09 5:09, quanyang.wang wrote:
>> Ping.
>>
>
> Could you resend the original patch (I have not received it) so I can 
> easily test and merge it?

OK, I will resend it.

Thanks,

Quanyang

>
> I'll find some time to do it soon.
>
> Best regards,
> Jyri
>
>> On 1/29/21 3:58 PM, Tomi Valkeinen wrote:
>>> Dropped the @ti.com addresses and added the new ones.
>>>
>>>   Tomi
>>>
>>> On 29/01/2021 07:58, quanyang.wang@...driver.com wrote:
>>>> From: Quanyang Wang <quanyang.wang@...driver.com>
>>>>
>>>> When run xrandr to change resolution on Beaglebone Black board, it 
>>>> will
>>>> print the error information:
>>>>
>>>> root@...glebone:~# xrandr -display :0 --output HDMI-1 --mode 720x400
>>>> [drm:drm_crtc_commit_wait] *ERROR* flip_done timed out
>>>> [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* 
>>>> [CRTC:32:tilcdc crtc] commit wait timed out
>>>> [drm:drm_crtc_commit_wait] *ERROR* flip_done timed out
>>>> [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* 
>>>> [CONNECTOR:34:HDMI-A-1] commit wait timed out
>>>> [drm:drm_crtc_commit_wait] *ERROR* flip_done timed out
>>>> [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* 
>>>> [PLANE:31:plane-0] commit wait timed out
>>>> tilcdc 4830e000.lcdc: already pending page flip!
>>>>
>>>> This is because there is operation sequence as below:
>>>>
>>>> drm_atomic_connector_commit_dpms(mode is DRM_MODE_DPMS_OFF):
>>>>      ...
>>>>      drm_atomic_helper_setup_commit <- 
>>>> init_completion(commit_A->flip_done)
>>>>      drm_atomic_helper_commit_tail
>>>>          tilcdc_crtc_atomic_disable
>>>>          tilcdc_plane_atomic_update <- drm_crtc_send_vblank_event 
>>>> in tilcdc_crtc_irq
>>>>                                        is skipped since 
>>>> tilcdc_crtc->enabled is 0
>>>>          tilcdc_crtc_atomic_flush   <- drm_crtc_send_vblank_event 
>>>> is skipped since
>>>> crtc->state->event is set to be NULL in
>>>> tilcdc_plane_atomic_update
>>>> drm_mode_setcrtc:
>>>>      ...
>>>>      drm_atomic_helper_setup_commit <- 
>>>> init_completion(commit_B->flip_done)
>>>>      drm_atomic_helper_wait_for_dependencies
>>>>          drm_crtc_commit_wait   <- wait for commit_A->flip_done 
>>>> completing
>>>>
>>>> Just as shown above, the steps which could complete 
>>>> commit_A->flip_done
>>>> are all skipped and commit_A->flip_done will never be completed. 
>>>> This will
>>>> result a time-out ERROR when drm_crtc_commit_wait check the 
>>>> commit_A->flip_done.
>>>> So add drm_crtc_send_vblank_event in tilcdc_crtc_atomic_disable to
>>>> complete commit_A->flip_done.
>>>>
>>>> Fixes: cb345decb4d2 ("drm/tilcdc: Use standard 
>>>> drm_atomic_helper_commit")
>>>> Signed-off-by: Quanyang Wang <quanyang.wang@...driver.com>
>>>> ---
>>>>   drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 9 +++++++++
>>>>   1 file changed, 9 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c 
>>>> b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
>>>> index 30213708fc99..d99afd19ca08 100644
>>>> --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
>>>> +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
>>>> @@ -515,6 +515,15 @@ static void tilcdc_crtc_off(struct drm_crtc 
>>>> *crtc, bool shutdown)
>>>>         drm_crtc_vblank_off(crtc);
>>>>   +    spin_lock_irq(&crtc->dev->event_lock);
>>>> +
>>>> +    if (crtc->state->event) {
>>>> +        drm_crtc_send_vblank_event(crtc, crtc->state->event);
>>>> +        crtc->state->event = NULL;
>>>> +    }
>>>> +
>>>> +    spin_unlock_irq(&crtc->dev->event_lock);
>>>> +
>>>>       tilcdc_crtc_disable_irqs(dev);
>>>>         pm_runtime_put_sync(dev->dev);
>>>>