Hi Bert,
I mischecked the code base. After checking the code on linux-next branch after
commit " drm/probe_helper: sort out poll_running vs poll_enabled ", I guess
below change in drm_probe_helper.c may help:
drm_kms_helper_poll_disable() {
......
+if (dev->mode_config.poll_enabled)
+ cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
....
This can tie workqueue output_poll_work to flag 'poll_enabled', as it's set
unconditionally after initing wq output_poll_work in drm_kms_helper_poll_init.
Regards,
Guchun
-----Original Message-----
From: Bert Karwatzki <spassw...@web.de>
Sent: Friday, February 24, 2023 11:58 PM
To: Chen, Guchun <guchun.c...@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/amd: use drm_kms_helper_poll_fini in
amdgpu_device_suspend to avoid warning
Am Freitag, dem 24.02.2023 um 02:26 +0000 schrieb Chen, Guchun:
> > Hi Bert,
> >
> > Thanks for your patch. As we will can drm_kms_helper_poll_enable in
> > resume, so it may not make sense using drm_kms_helper_poll_fini in
> > suspend, from code pairing perspective.
> >
> > For your case, is it possible to fix the problem by limiting the
> > access of drm_kms_helper_poll_disable with checking
> > mode_config_initialized in adev structure? We can get rid of the
> > code change in drm core in this way.
> >
> > Regards,
> > Guchun
> >
> > -----Original Message-----
> > From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> On Behalf Of
> > Bert Karwatzki
> > Sent: Friday, February 24, 2023 4:52 AM
> > To: amd-gfx@lists.freedesktop.org
> > Subject: Re: [PATCH] drm/amd: use drm_kms_helper_poll_fini in
> > amdgpu_device_suspend to avoid warning
> >
> > When drm_kms_helper_poll_disable is used in amdgpu_device_suspend
> > without drm_kms_helper_poll_init having been called it causes a
> > warning in __flush_work:
> > https://gitlab.freedesktop.org/drm/amd/-/issues/2411
> > To avoid this one can use drm_kms_helper_poll_fini instead:
> > Send a second time because Evolution seems to have garbled the first
> > patch.
> >
> > From 51cba3ae1e9f557cca8e37eb43b9b9310d0d504d Mon Sep 17 00:00:00
> > 2001
> > From: Bert Karwatzki <spassw...@web.de>
> > Date: Thu, 16 Feb 2023 10:34:11 +0100
> > Subject: [PATCH] Use drm_kms_helper_poll_fini instead of
> > drm_kms_helper_poll_disable in amdgpu_device.c to avoid a warning
> > from
> > __flush_work.
> >
> > Signed-off-by: Bert Karwatzki <spassw...@web.de>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
> > drivers/gpu/drm/drm_probe_helper.c | 7 ++++---
> > 2 files changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > index b325f7039e0e..dc9e9868a84b 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > @@ -4145,7 +4145,7 @@ int amdgpu_device_suspend(struct drm_device
> > *dev, bool fbcon)
> > if (amdgpu_acpi_smart_shift_update(dev, AMDGPU_SS_DEV_D3))
> > DRM_WARN("smart shift update failed\n");
> >
> > - drm_kms_helper_poll_disable(dev);
> > + drm_kms_helper_poll_fini(dev);
> >
> > if (fbcon)
> > drm_fb_helper_set_suspend_unlocked(adev_to_drm(adev
> > )-
> > > > fb_helper, true);
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c
> > b/drivers/gpu/drm/drm_probe_helper.c
> > index 8127be134c39..105d00d5ebf3 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -842,9 +842,10 @@ EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
> > *
> > * This function disables the output polling work.
> > *
> > - * Drivers can call this helper from their device suspend
> > implementation. It is
> > - * not an error to call this even when output polling isn't enabled
> > or already
> > - * disabled. Polling is re-enabled by calling
> > drm_kms_helper_poll_enable().
> > + * Drivers can call this helper from their device suspend
> > implementation. If it
> > + * is not known if drm_kms_helper_poll_init has been called before
> > the
> > driver
> > + * should use drm_kms_helper_poll_fini_instead.
> > + * Polling is re-enabled by calling drm_kms_helper_poll_enable().
> > *
> > * Note that calls to enable and disable polling must be strictly
> > ordered, which
> > * is automatically the case when they're only call from
> > suspend/resume
> >
No, that does not work for me. I tried (in linux-next-20230224):
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index c4a4e2fe6681..27fb42b1bde4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4145,7 +4145,13 @@ int amdgpu_device_suspend(struct drm_device *dev, bool
fbcon)
if (amdgpu_acpi_smart_shift_update(dev, AMDGPU_SS_DEV_D3))
DRM_WARN("smart shift update failed\n");
- drm_kms_helper_poll_disable(dev);
+ if (adev->mode_info.mode_config_initialized) {
+ printk(KERN_INFO "adev-
> mode_info.mode_config_initialized = %d\n",
+ adev-
> mode_info.mode_config_initialized);
+ printk(KERN_INFO "dev->mode_config.poll_enabled =
%d\n",
+ dev->mode_config.poll_enabled);
+ drm_kms_helper_poll_disable(dev);
+ }
if (fbcon)
drm_fb_helper_set_suspend_unlocked(adev_to_drm(adev)-
> fb_helper, true);
and found that mode_config_initialized=1 but dev-
> mode_config.poll_enabled=0 with the usual warning:
[ 23.287058] adev->mode_info.mode_config_initialized = 1 [ 23.287061]
dev->mode_config.poll_enabled = 0 [ 23.287063] ------------[ cut here
]------------ [ 23.287064] WARNING: CPU: 0 PID: 16 at kernel/workqueue.c:3167
__flush_work.isra.0+0x261/0x270
The flag that needs to be checked to avoid the warning is dev-
> mode_config.poll_enabled which gets set by drm_kms_helper_poll_init
and drm_kms_helper_poll_fini does just that. Changing the comment of
drms_kms_helper_poll_disable is technically not necessary though.
(resent because this mail didn't appear in the archive of amd-gfx so I thought
it might have been lost) Bert Karwatzki
