From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Ahsan Hussain <ahsan_hussain@mentor.com>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: drm: understanding the kernel warning during drm_vblank_cleanup()
Date: Thu, 29 Nov 2018 17:19:28 +0200 [thread overview]
Message-ID: <20181129151928.GM9144@intel.com> (raw)
In-Reply-To: <6198455d-59b4-c4b0-94c1-6e0d460f2451@mentor.com>
On Thu, Nov 29, 2018 at 07:30:45PM +0500, Ahsan Hussain wrote:
> Hi folks,
>
> I'm new to DRM and trying to understand the warning in
> drivers/gpu/drm/drm_vblank.c during drm_vblank_cleanup().
>
> WARN_ON(READ_ONCE(vblank->enabled) &&
> drm_core_check_feature(dev, DRIVER_MODESET));
>
> Is the drm driver responsible for making sure that !(vblank->enabled) in
> the .unbind operation, or is this something related to userspace? What
> does the warning signify? Git history did not help here at all.
It signifies you haven't cleaned up things properly. Usually what
you would do is call drm_atomic_helper_shutdown() which will also
end up turnng vblank interrupts off, assuming you use
drm_vblank_on()/off() properly.
--
Ville Syrjälä
Intel
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WARNING: multiple messages have this Message-ID (diff)
From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Ahsan Hussain <ahsan_hussain@mentor.com>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: drm: understanding the kernel warning during drm_vblank_cleanup()
Date: Thu, 29 Nov 2018 17:19:28 +0200 [thread overview]
Message-ID: <20181129151928.GM9144@intel.com> (raw)
In-Reply-To: <6198455d-59b4-c4b0-94c1-6e0d460f2451@mentor.com>
On Thu, Nov 29, 2018 at 07:30:45PM +0500, Ahsan Hussain wrote:
> Hi folks,
>
> I'm new to DRM and trying to understand the warning in
> drivers/gpu/drm/drm_vblank.c during drm_vblank_cleanup().
>
> WARN_ON(READ_ONCE(vblank->enabled) &&
> drm_core_check_feature(dev, DRIVER_MODESET));
>
> Is the drm driver responsible for making sure that !(vblank->enabled) in
> the .unbind operation, or is this something related to userspace? What
> does the warning signify? Git history did not help here at all.
It signifies you haven't cleaned up things properly. Usually what
you would do is call drm_atomic_helper_shutdown() which will also
end up turnng vblank interrupts off, assuming you use
drm_vblank_on()/off() properly.
--
Ville Syrjälä
Intel
next prev parent reply other threads:[~2018-11-29 15:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 14:30 drm: understanding the kernel warning during drm_vblank_cleanup() Ahsan Hussain
2018-11-29 14:30 ` Ahsan Hussain
2018-11-29 15:19 ` Ville Syrjälä [this message]
2018-11-29 15:19 ` Ville Syrjälä
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