lkml.org 
[lkml]   [2022]   [Jun]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2] drm/msm: Switch ordering of runpm put vs devfreq_idle
Hi,

On Wed, Jun 8, 2022 at 9:13 AM Rob Clark <robdclark@gmail.com> wrote:
>
> From: Rob Clark <robdclark@chromium.org>
>
> I've seen a few crashes like:
>
> CPU: 0 PID: 216 Comm: A618-worker Tainted: G W 5.4.196 #7
> Hardware name: Google Wormdingler rev1+ INX panel board (DT)
> pstate: 20c00009 (nzCv daif +PAN +UAO)
> pc : msm_readl+0x14/0x34
> lr : a6xx_gpu_busy+0x40/0x80
> sp : ffffffc011b93ad0
> x29: ffffffc011b93ad0 x28: ffffffe77cba3000
> x27: 0000000000000001 x26: ffffffe77bb4c4ac
> x25: ffffffa2f227dfa0 x24: ffffffa2f22aab28
> x23: 0000000000000000 x22: ffffffa2f22bf020
> x21: ffffffa2f22bf000 x20: ffffffc011b93b10
> x19: ffffffc011bd4110 x18: 000000000000000e
> x17: 0000000000000004 x16: 000000000000000c
> x15: 000001be3a969450 x14: 0000000000000400
> x13: 00000000000101d6 x12: 0000000034155555
> x11: 0000000000000001 x10: 0000000000000000
> x9 : 0000000100000000 x8 : ffffffc011bd4000
> x7 : 0000000000000000 x6 : 0000000000000007
> x5 : ffffffc01d8b38f0 x4 : 0000000000000000
> x3 : 00000000ffffffff x2 : 0000000000000002
> x1 : 0000000000000000 x0 : ffffffc011bd4110
> Call trace:
> msm_readl+0x14/0x34
> a6xx_gpu_busy+0x40/0x80
> msm_devfreq_get_dev_status+0x70/0x1d0
> devfreq_simple_ondemand_func+0x34/0x100
> update_devfreq+0x50/0xe8
> qos_notifier_call+0x2c/0x64
> qos_max_notifier_call+0x1c/0x2c
> notifier_call_chain+0x58/0x98
> __blocking_notifier_call_chain+0x74/0x84
> blocking_notifier_call_chain+0x38/0x48
> pm_qos_update_target+0xf8/0x19c
> freq_qos_apply+0x54/0x6c
> apply_constraint+0x60/0x104
> __dev_pm_qos_update_request+0xb4/0x184
> dev_pm_qos_update_request+0x38/0x58
> msm_devfreq_idle_work+0x34/0x40
> kthread_worker_fn+0x144/0x1c8
> kthread+0x140/0x284
> ret_from_fork+0x10/0x18
> Code: f9000bf3 910003fd aa0003f3 d503201f (b9400260)
> ---[ end trace f6309767a42d0831 ]---
>
> Which smells a lot like touching hw after power collapse. This seems
> a bit like a race/timing issue elsewhere, as pm_runtime_get_if_in_use()
> in a6xx_gpu_busy() should have kept us from touching hw if it wasn't
> powered.

I dunno if we want to change the commit message since I think my patch
[1] addresses the above problem?

[1] https://lore.kernel.org/r/20220609094716.v2.1.Ie846c5352bc307ee4248d7cab998ab3016b85d06@changeid


> But, we've seen cases where the idle_work scheduled by
> msm_devfreq_idle() ends up racing with the resume path. Which, again,
> shouldn't be a problem other than unnecessary freq changes.
>
> v2. Only move the runpm _put_autosuspend, and not the _mark_last_busy()
>
> Fixes: 9bc95570175a ("drm/msm: Devfreq tuning")
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Link: https://lore.kernel.org/r/20210927152928.831245-1-robdclark@gmail.com
> ---
> drivers/gpu/drm/msm/msm_gpu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

In any case, your patch fixes the potential WARN_ON and seems like the
right thing to do, so:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

\
 
 \ /
  Last update: 2022-06-09 18:52    [W:0.060 / U:1.844 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site