From: Thierry Reding <thierry.reding@gmail.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Liviu Dudau <liviu.dudau@arm.com>,
DRI Development <dri-devel@lists.freedesktop.org>,
Daniel Vetter <daniel.vetter@intel.com>,
Mihail Atanassov <mihail.atanassov@arm.com>,
Sam Ravnborg <sam@ravnborg.org>,
Emil Velikov <emil.velikov@collabora.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
David Airlie <airlied@linux.ie>,
Ludovic Desroches <ludovic.desroches@microchip.com>,
Tomi Valkeinen <tomi.valkeinen@ti.com>,
"James \(Qian\) Wang" <james.qian.wang@arm.com>,
syzbot+0871b14ca2e2fb64f6e3@syzkaller.appspotmail.com,
Thomas Zimmermann <tzimmermann@suse.de>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
Jyri Sarha <jsarha@ti.com>, Sean Paul <seanpaul@chromium.org>,
linux-tegra@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Boris Brezillon <bbrezillon@kernel.org>,
Nicolas Ferre <nicolas.ferre@microchip.com>,
zhengbin <zhengbin13@huawei.com>,
Brian Masney <masneyb@onstation.org>
Subject: Re: [PATCH] drm/atomic-helper: reset vblank on crtc reset
Date: Wed, 27 May 2020 12:52:47 +0200 [thread overview]
Message-ID: <20200527105247.GA2979001@ulmo> (raw)
In-Reply-To: <20200527095332.1439425-1-daniel.vetter@ffwll.ch>
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On Wed, May 27, 2020 at 11:53:32AM +0200, Daniel Vetter wrote:
> Only when vblanks are supported ofc.
>
> Some drivers do this already, but most unfortunately missed it. This
> opens up bugs after driver load, before the crtc is enabled for the
> first time. syzbot spotted this when loading vkms as a secondary
> output. Given how many drivers are buggy it's best to solve this once
> and for all in shared helper code.
>
> Aside from moving the few existing calls to drm_crtc_vblank_reset into
> helpers (i915 doesn't use helpers, so keeps its own) I think the
> regression risk is minimal: atomic helpers already rely on drivers
> calling drm_crtc_vblank_on/off correctly in their hooks when they
> support vblanks. And driver that's failing to handle vblanks after
> this is missing those calls already, and vblanks could only work by
> accident when enabling a CRTC for the first time right after boot.
>
> Big thanks to Tetsuo for helping track down what's going wrong here.
>
> There's only a few drivers which already had the necessary call and
> needed some updating:
> - komeda, atmel and tidss also needed to be changed to call
> __drm_atomic_helper_crtc_reset() intead of open coding it
> - tegra and msm even had it in the same place already, just code
> motion, and malidp already uses __drm_atomic_helper_crtc_reset().
>
> Only call left is in i915, which doesn't use drm_mode_config_reset,
> but has its own fastboot infrastructure. So that's the only case where
> we actually want this in the driver still.
>
> I've also reviewed all other drivers which set up vblank support with
> drm_vblank_init. After the previous patch fixing mxsfb all atomic
> drivers do call drm_crtc_vblank_on/off as they should, the remaining
> drivers are either legacy kms or legacy dri1 drivers, so not affected
> by this change to atomic helpers.
>
> v2: Use the drm_dev_has_vblank() helper.
>
> Link: https://syzkaller.appspot.com/bug?id=0ba17d70d062b2595e1f061231474800f076c7cb
> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Reported-by: syzbot+0871b14ca2e2fb64f6e3@syzkaller.appspotmail.com
> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Cc: "James (Qian) Wang" <james.qian.wang@arm.com>
> Cc: Liviu Dudau <liviu.dudau@arm.com>
> Cc: Mihail Atanassov <mihail.atanassov@arm.com>
> Cc: Brian Starkey <brian.starkey@arm.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Boris Brezillon <bbrezillon@kernel.org>
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Jonathan Hunter <jonathanh@nvidia.com>
> Cc: Jyri Sarha <jsarha@ti.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: Sean Paul <seanpaul@chromium.org>
> Cc: Brian Masney <masneyb@onstation.org>
> Cc: Emil Velikov <emil.velikov@collabora.com>
> Cc: zhengbin <zhengbin13@huawei.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-tegra@vger.kernel.org
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
> drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 7 ++-----
> drivers/gpu/drm/arm/malidp_drv.c | 1 -
> drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 7 ++-----
> drivers/gpu/drm/drm_atomic_state_helper.c | 4 ++++
> drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c | 2 --
> drivers/gpu/drm/tegra/dc.c | 1 -
> drivers/gpu/drm/tidss/tidss_crtc.c | 3 +--
> drivers/gpu/drm/tidss/tidss_kms.c | 4 ----
> 8 files changed, 9 insertions(+), 20 deletions(-)
Looks good, and nice cleanup:
Acked-by: Thierry Reding <treding@nvidia.com>
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next prev parent reply other threads:[~2020-05-27 10:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 9:47 [PATCH 1/2] drm/mxsfb: Call drm_crtc_vblank_on/off Daniel Vetter
2020-05-27 9:47 ` [PATCH 2/2] drm/atomic-helper: reset vblank on crtc reset Daniel Vetter
2020-05-27 9:53 ` [PATCH] " Daniel Vetter
2020-05-27 10:52 ` Thierry Reding [this message]
2020-05-27 10:57 ` Liviu Dudau
2020-05-27 11:07 ` Daniel Vetter
2020-05-27 12:08 ` Liviu Dudau
2020-05-27 14:21 ` Daniel Vetter
2020-05-30 3:22 ` Laurent Pinchart
2020-06-02 9:43 ` Daniel Vetter
2020-06-01 17:19 ` Liviu Dudau
2020-05-27 15:42 ` [PATCH 2/2] " Daniel Vetter
2020-05-29 11:58 ` Daniel Vetter
2020-05-29 12:02 ` Boris Brezillon
2020-05-28 5:46 ` [PATCH 1/2] drm/mxsfb: Call drm_crtc_vblank_on/off Daniel Vetter
2020-05-28 7:56 ` Stefan Agner
2020-05-28 8:06 ` Daniel Vetter
2020-05-28 8:19 ` Stefan Agner
2020-05-28 8:25 ` Daniel Vetter
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