Re: [PATCH v10 11/15] drm/atomic-helper: Set fence deadline for vblank

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: "Rob Clark" <robdclark@gmail.com>,
	dri-devel@lists.freedesktop.org,
	"Rob Clark" <robdclark@chromium.org>,
	"Christian König" <ckoenig.leichtzumerken@gmail.com>,
	intel-gfx@lists.freedesktop.org,
	"open list" <linux-kernel@vger.kernel.org>,
	"Luben Tuikov" <luben.tuikov@amd.com>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Matt Turner" <mattst88@gmail.com>,
	freedreno@lists.freedesktop.org
Subject: Re: [PATCH v10 11/15] drm/atomic-helper: Set fence deadline for vblank
Date: Wed, 5 Apr 2023 00:53:29 +0300	[thread overview]
Message-ID: <198c42ad-73de-9e9d-23d4-f36cb6840b5d@linaro.org> (raw)
In-Reply-To: <ZCx3jUJfC1vmbhI6@phenom.ffwll.local>

On 04/04/2023 22:16, Daniel Vetter wrote:
> On Tue, Apr 04, 2023 at 08:22:05PM +0300, Dmitry Baryshkov wrote:
>> On 08/03/2023 17:53, Rob Clark wrote:
>>> From: Rob Clark <robdclark@chromium.org>
>>>
>>> For an atomic commit updating a single CRTC (ie. a pageflip) calculate
>>> the next vblank time, and inform the fence(s) of that deadline.
>>>
>>> v2: Comment typo fix (danvet)
>>> v3: If there are multiple CRTCs, consider the time of the soonest vblank
>>>
>>> Signed-off-by: Rob Clark <robdclark@chromium.org>
>>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>> Signed-off-by: Rob Clark <robdclark@chromium.org>
>>> ---
>>>    drivers/gpu/drm/drm_atomic_helper.c | 37 +++++++++++++++++++++++++++++
>>>    1 file changed, 37 insertions(+)
>>
>> As I started playing with hotplug on RB5 (sm8250, DSI-HDMI bridge), I found
>> that this patch introduces the following backtrace on HDMI hotplug. Is there
>> anything that I can do to debug/fix the issue? The warning seems harmless,
>> but it would be probably be good to still fix it. With addresses decoded:
> 
> Bit a shot in the dark, but does the below help?

This indeed seems to fix the issue. I'm not sure about the possible side 
effects, but, if you were to send the patch:

Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> 
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index f21b5a74176c..6640d80d84f3 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1528,6 +1528,9 @@ static void set_fence_deadline(struct drm_device *dev,
>   	for_each_new_crtc_in_state (state, crtc, new_crtc_state, i) {
>   		ktime_t v;
>   
> +		if (drm_atomic_crtc_needs_modeset(new_crtc_state))
> +			continue;
> +
>   		if (drm_crtc_next_vblank_start(crtc, &v))
>   			continue;
>   
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 78a8c51a4abf..7ae38e8e27e8 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -1001,6 +1001,9 @@ int drm_crtc_next_vblank_start(struct drm_crtc *crtc, ktime_t *vblanktime)
>   	struct drm_display_mode *mode = &vblank->hwmode;
>   	u64 vblank_start;
>   
> +	if (!drm_dev_has_vblank(crtc->dev))
> +		return -EINVAL;
> +
>   	if (!vblank->framedur_ns || !vblank->linedur_ns)
>   		return -EINVAL;
>   
> 
>>
>> [   31.151348] ------------[ cut here ]------------
>> [   31.157043] msm_dpu ae01000.display-controller:
>> drm_WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev))
>> [   31.157177] WARNING: CPU: 0 PID: 13 at drivers/gpu/drm/drm_vblank.c:728
>> drm_crtc_vblank_helper_get_vblank_timestamp_internal
>> (drivers/gpu/drm/drm_vblank.c:728)
>> [   31.180629] Modules linked in:
>> [   31.184106] CPU: 0 PID: 13 Comm: kworker/0:1 Not tainted
>> 6.3.0-rc2-00008-gd39e48ca80c0 #542
>> [   31.193358] Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
>> [   31.200796] Workqueue: events lt9611uxc_hpd_work
>> [   31.205990] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>> BTYPE=--)
>> [   31.213722] pc : drm_crtc_vblank_helper_get_vblank_timestamp_internal
>> (drivers/gpu/drm/drm_vblank.c:728)
>> [   31.222032] lr : drm_crtc_vblank_helper_get_vblank_timestamp_internal
>> (drivers/gpu/drm/drm_vblank.c:728)
>> [   31.230341] sp : ffff8000080bb8d0
>> [   31.234061] x29: ffff8000080bb900 x28: 0000000000000038 x27:
>> ffff61a7956b8d60
>> [   31.242051] x26: 0000000000000000 x25: 0000000000000000 x24:
>> ffff8000080bb9c4
>> [   31.250038] x23: 0000000000000001 x22: ffffbf0033b94ef0 x21:
>> ffff61a7957901d0
>> [   31.258029] x20: ffff61a795710000 x19: ffff61a78128b000 x18:
>> fffffffffffec278
>> [   31.266014] x17: 0040000000000465 x16: 0000000000000020 x15:
>> 0000000000000060
>> [   31.274001] x14: 0000000000000001 x13: ffffbf00354550e0 x12:
>> 0000000000000825
>> [   31.281989] x11: 00000000000002b7 x10: ffffbf00354b1208 x9 :
>> ffffbf00354550e0
>> [   31.289976] x8 : 00000000ffffefff x7 : ffffbf00354ad0e0 x6 :
>> 00000000000002b7
>> [   31.297963] x5 : ffff61a8feebbe48 x4 : 40000000fffff2b7 x3 :
>> ffffa2a8c9f64000
>> [   31.305947] x2 : 0000000000000000 x1 : 0000000000000000 x0 :
>> ffff61a780283100
>> [   31.313934] Call trace:
>> [   31.316719] drm_crtc_vblank_helper_get_vblank_timestamp_internal
>> (drivers/gpu/drm/drm_vblank.c:728)
>> [   31.324646] drm_crtc_vblank_helper_get_vblank_timestamp
>> (drivers/gpu/drm/drm_vblank.c:843)
>> [   31.331528] drm_crtc_get_last_vbltimestamp
>> (drivers/gpu/drm/drm_vblank.c:884)
>> [   31.337170] drm_crtc_next_vblank_start
>> (drivers/gpu/drm/drm_vblank.c:1006)
>> [   31.342430] drm_atomic_helper_wait_for_fences
>> (drivers/gpu/drm/drm_atomic_helper.c:1531
>> drivers/gpu/drm/drm_atomic_helper.c:1578)
>> [   31.348561] drm_atomic_helper_commit
>> (drivers/gpu/drm/drm_atomic_helper.c:2007)
>> [   31.353724] drm_atomic_commit (drivers/gpu/drm/drm_atomic.c:1444)
>> [   31.358127] drm_client_modeset_commit_atomic
>> (drivers/gpu/drm/drm_client_modeset.c:1045)
>> [   31.364146] drm_client_modeset_commit_locked
>> (drivers/gpu/drm/drm_client_modeset.c:1148)
>> [   31.370071] drm_client_modeset_commit
>> (drivers/gpu/drm/drm_client_modeset.c:1174)
>> [   31.375233] drm_fb_helper_set_par (drivers/gpu/drm/drm_fb_helper.c:254
>> drivers/gpu/drm/drm_fb_helper.c:229 drivers/gpu/drm/drm_fb_helper.c:1644)
>> [   31.380108] drm_fb_helper_hotplug_event
>> (drivers/gpu/drm/drm_fb_helper.c:2302 (discriminator 4))
>> [   31.385456] drm_fb_helper_output_poll_changed
>> (drivers/gpu/drm/drm_fb_helper.c:2331)
>> [   31.391376] drm_kms_helper_hotplug_event
>> (drivers/gpu/drm/drm_probe_helper.c:697)
>> [   31.396825] drm_bridge_connector_hpd_cb
>> (drivers/gpu/drm/drm_bridge_connector.c:129)
>> [   31.402175] drm_bridge_hpd_notify (drivers/gpu/drm/drm_bridge.c:1315)
>> [   31.406954] lt9611uxc_hpd_work
>> (drivers/gpu/drm/bridge/lontium-lt9611uxc.c:185)
>> [   31.411450] process_one_work (kernel/workqueue.c:2395)
>> [   31.415949] worker_thread (include/linux/list.h:292
>> kernel/workqueue.c:2538)
>> [   31.426843] kthread (kernel/kthread.c:376)
>> [   31.437182] ret_from_fork (arch/arm64/kernel/entry.S:871)
>> [   31.447828] irq event stamp: 44642
>> [   31.458284] hardirqs last enabled at (44641): __up_console_sem
>> (arch/arm64/include/asm/irqflags.h:182 (discriminator 1)
>> arch/arm64/include/asm/irqflags.h:202 (discriminator 1)
>> kernel/printk/printk.c:345 (discriminator 1))
>> [   31.474540] hardirqs last disabled at (44642): el1_dbg
>> (arch/arm64/kernel/entry-common.c:335 arch/arm64/kernel/entry-common.c:406)
>> [   31.489882] softirqs last enabled at (42912): _stext
>> (arch/arm64/include/asm/current.h:19 arch/arm64/include/asm/preempt.h:13
>> kernel/softirq.c:415 kernel/softirq.c:600)
>> [   31.505256] softirqs last disabled at (42907): ____do_softirq
>> (arch/arm64/kernel/irq.c:81)
>> [   31.521139] ---[ end trace 0000000000000000 ]---
>>
>>
>>
>> -- 
>> With best wishes
>> Dmitry
>>
> 

-- 
With best wishes
Dmitry