From: "Michel Dänzer" <michel@daenzer.net>
To: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>,
dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/radeon: Don't hang in radeon_flip_work_func on disabled crtc. (v2)
Date: Fri, 19 Feb 2016 10:16:42 +0900 [thread overview]
Message-ID: <56C66CFA.8030809@daenzer.net> (raw)
In-Reply-To: <1455843999-19179-2-git-send-email-mario.kleiner.de@gmail.com>
On 19.02.2016 10:06, Mario Kleiner wrote:
> This fixes a regression introduced in Linux 4.4.
>
> Limit the amount of time radeon_flip_work_func can
> delay programming a page flip, by both limiting the
> maximum amount of time per wait cycle and the maximum
> number of wait cycles. Continue the flip if the limit
> is exceeded, even if that may result in a visual or
> timing glitch.
>
> This is to prevent a hang of page flips, as reported
> in fdo bug #93746: Disconnecting a DisplayPort display
> in parallel to a kms pageflip getting queued can cause
> the following hang of page flips and thereby an unusable
> desktop:
>
> 1. kms pageflip ioctl() queues pageflip -> queues execution
> of radeon_flip_work_func.
>
> 2. Hotunplug of display causes the driver to DPMS OFF
> the unplugged display. Display engine shuts down,
> scanout no longer moves, but stays at its resting
> position at start line of vblank.
>
> 3. radeon_flip_work_func executes while crtc is off, and
> due to the non-moving scanout position, the new flip
> delay code introduced into Linux 4.4 by
> commit 5b5561b3660d ("drm/radeon: Fixup hw vblank counter/ts..")
> enters an infinite wait loop.
>
> 4. After reconnecting the display, the pageflip continues
> to hang in 3. and the display doesn't update its view
> of the desktop.
>
> This patch fixes the Linux 4.4 regression from fdo bug #93746
>
> <https://bugs.freedesktop.org/show_bug.cgi?id=93746>
>
> v2: Skip wait immediately if !radeon_crtc->enabled, as
> suggested by Michel.
>
> Reported-by: Bernd Steinhauser <linux@bernd-steinhauser.de>
> Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
> Tested-by: Bernd Steinhauser <linux@bernd-steinhauser.de>
>
> Cc: <stable@vger.kernel.org> # 4.4+
Both patches are
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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next prev parent reply other threads:[~2016-02-19 1:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-19 1:06 radeon/amdgpu pageflip regression fixes for Linux 4.4+ Mario Kleiner
2016-02-19 1:06 ` [PATCH 1/2] drm/radeon: Don't hang in radeon_flip_work_func on disabled crtc. (v2) Mario Kleiner
2016-02-19 1:06 ` Mario Kleiner
2016-02-19 1:16 ` Michel Dänzer [this message]
2016-02-19 22:17 ` Alex Deucher
2016-02-19 1:06 ` [PATCH 2/2] drm/amdgpu: Don't hang in amdgpu_flip_work_func on disabled crtc Mario Kleiner
2016-02-19 1:06 ` Mario Kleiner
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