Re: [Intel-gfx] [PATCH 1/3] drm/atomic-helper: reset vblank on crtc reset
On Wed, Jun 3, 2020 at 2:19 AM Laurent Pinchart
wrote:
>
> Hi Daniel,
>
> Thank you for the patch.
>
> May I remind you about the -v option to git-format-patch ? :-) Seriously
> speaking, it really helps review.
>
> On Tue, Jun 02, 2020 at 11:51:38AM +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.
> >
> > v3: Laurent pointed out that omap and rcar-du used drm_crtc_vblank_off
> > instead of drm_crtc_vblank_reset. Adjust them too.
> >
> > Cc: Laurent Pinchart
> > Reviewed-by: Laurent Pinchart
> > Reviewed-by: Boris Brezillon
> > Acked-by: Liviu Dudau
> > Acked-by: Thierry Reding
> > Link:
> > https://syzkaller.appspot.com/bug?id=0ba17d70d062b2595e1f061231474800f076c7cb
> > Reported-by: Tetsuo Handa
> > Reported-by: syzbot+0871b14ca2e2fb64f...@syzkaller.appspotmail.com
> > Cc: Tetsuo Handa
> > Cc: "James (Qian) Wang"
> > Cc: Liviu Dudau
> > Cc: Mihail Atanassov
> > Cc: Brian Starkey
> > Cc: Sam Ravnborg
> > Cc: Boris Brezillon
> > Cc: Nicolas Ferre
> > Cc: Alexandre Belloni
> > Cc: Ludovic Desroches
> > Cc: Maarten Lankhorst
> > Cc: Maxime Ripard
> > Cc: Thomas Zimmermann
> > Cc: David Airlie
> > Cc: Daniel Vetter
> > Cc: Thierry Reding
> > Cc: Jonathan Hunter
> > Cc: Jyri Sarha
> > Cc: Tomi Valkeinen
> > Cc: Rob Clark
> > Cc: Sean Paul
> > Cc: Brian Masney
> > Cc: Emil Velikov
> > Cc: zhengbin
> > Cc: Thomas Gleixner
> > Cc: linux-te...@vger.kernel.org
> > Signed-off-by: Daniel Vetter
> > ---
> > 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/omapdrm/omap_drv.c | 3 ---
> > drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 3 ---
> > drivers/gpu/drm/tegra/dc.c | 1 -
> > drivers/gpu/drm/tidss/tidss_crtc.c | 3 +--
> > drivers/gpu/drm/tidss/tidss_kms.c| 4
> > 10 files changed, 9 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > index 56bd938961ee..f33418d6e1a0 100644
> > --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > @@ -492,10 +492,8 @@ static void komeda_crtc_reset(struct drm_crtc *crtc)
> > crtc->state = NULL;
> >
> > state = kzalloc(sizeof(*state), GFP_KERNEL);
> > - if (state) {
> > - crtc->state = >base;
> > - crtc->state->crtc = crtc;
> > - }
> > + if (state)
> > + __drm_atomic_helper_crtc_reset(crtc, >base);
> > }
> >
> > static struct drm_crtc_state *
> > @@ -616,7 +614,6 @@ static int komeda_crtc_add(struct komeda_kms_dev *kms,
> > return err;
> >
> > drm_crtc_helper_add(crtc, _crtc_helper_funcs);
> > - drm_crtc_vblank_reset(crtc);
> >
> > crtc->port = kcrtc->master->of_output_port;
> >
> > diff
Re: [Intel-gfx] [PATCH 1/3] drm/atomic-helper: reset vblank on crtc reset
Hi Daniel,
Thank you for the patch.
May I remind you about the -v option to git-format-patch ? :-) Seriously
speaking, it really helps review.
On Tue, Jun 02, 2020 at 11:51:38AM +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.
>
> v3: Laurent pointed out that omap and rcar-du used drm_crtc_vblank_off
> instead of drm_crtc_vblank_reset. Adjust them too.
>
> Cc: Laurent Pinchart
> Reviewed-by: Laurent Pinchart
> Reviewed-by: Boris Brezillon
> Acked-by: Liviu Dudau
> Acked-by: Thierry Reding
> Link:
> https://syzkaller.appspot.com/bug?id=0ba17d70d062b2595e1f061231474800f076c7cb
> Reported-by: Tetsuo Handa
> Reported-by: syzbot+0871b14ca2e2fb64f...@syzkaller.appspotmail.com
> Cc: Tetsuo Handa
> Cc: "James (Qian) Wang"
> Cc: Liviu Dudau
> Cc: Mihail Atanassov
> Cc: Brian Starkey
> Cc: Sam Ravnborg
> Cc: Boris Brezillon
> Cc: Nicolas Ferre
> Cc: Alexandre Belloni
> Cc: Ludovic Desroches
> Cc: Maarten Lankhorst
> Cc: Maxime Ripard
> Cc: Thomas Zimmermann
> Cc: David Airlie
> Cc: Daniel Vetter
> Cc: Thierry Reding
> Cc: Jonathan Hunter
> Cc: Jyri Sarha
> Cc: Tomi Valkeinen
> Cc: Rob Clark
> Cc: Sean Paul
> Cc: Brian Masney
> Cc: Emil Velikov
> Cc: zhengbin
> Cc: Thomas Gleixner
> Cc: linux-te...@vger.kernel.org
> Signed-off-by: Daniel Vetter
> ---
> 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/omapdrm/omap_drv.c | 3 ---
> drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 3 ---
> drivers/gpu/drm/tegra/dc.c | 1 -
> drivers/gpu/drm/tidss/tidss_crtc.c | 3 +--
> drivers/gpu/drm/tidss/tidss_kms.c| 4
> 10 files changed, 9 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> index 56bd938961ee..f33418d6e1a0 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> @@ -492,10 +492,8 @@ static void komeda_crtc_reset(struct drm_crtc *crtc)
> crtc->state = NULL;
>
> state = kzalloc(sizeof(*state), GFP_KERNEL);
> - if (state) {
> - crtc->state = >base;
> - crtc->state->crtc = crtc;
> - }
> + if (state)
> + __drm_atomic_helper_crtc_reset(crtc, >base);
> }
>
> static struct drm_crtc_state *
> @@ -616,7 +614,6 @@ static int komeda_crtc_add(struct komeda_kms_dev *kms,
> return err;
>
> drm_crtc_helper_add(crtc, _crtc_helper_funcs);
> - drm_crtc_vblank_reset(crtc);
>
> crtc->port = kcrtc->master->of_output_port;
>
> diff --git a/drivers/gpu/drm/arm/malidp_drv.c
> b/drivers/gpu/drm/arm/malidp_drv.c
> index c2507b7d8512..02904392e370 100644
> --- a/drivers/gpu/drm/arm/malidp_drv.c
> +++ b/drivers/gpu/drm/arm/malidp_drv.c
> @@ -870,7 +870,6 @@ static int malidp_bind(struct device *dev)
>
[Intel-gfx] [PATCH 1/3] drm/atomic-helper: reset vblank on crtc reset
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.
v3: Laurent pointed out that omap and rcar-du used drm_crtc_vblank_off
instead of drm_crtc_vblank_reset. Adjust them too.
Cc: Laurent Pinchart
Reviewed-by: Laurent Pinchart
Reviewed-by: Boris Brezillon
Acked-by: Liviu Dudau
Acked-by: Thierry Reding
Link:
https://syzkaller.appspot.com/bug?id=0ba17d70d062b2595e1f061231474800f076c7cb
Reported-by: Tetsuo Handa
Reported-by: syzbot+0871b14ca2e2fb64f...@syzkaller.appspotmail.com
Cc: Tetsuo Handa
Cc: "James (Qian) Wang"
Cc: Liviu Dudau
Cc: Mihail Atanassov
Cc: Brian Starkey
Cc: Sam Ravnborg
Cc: Boris Brezillon
Cc: Nicolas Ferre
Cc: Alexandre Belloni
Cc: Ludovic Desroches
Cc: Maarten Lankhorst
Cc: Maxime Ripard
Cc: Thomas Zimmermann
Cc: David Airlie
Cc: Daniel Vetter
Cc: Thierry Reding
Cc: Jonathan Hunter
Cc: Jyri Sarha
Cc: Tomi Valkeinen
Cc: Rob Clark
Cc: Sean Paul
Cc: Brian Masney
Cc: Emil Velikov
Cc: zhengbin
Cc: Thomas Gleixner
Cc: linux-te...@vger.kernel.org
Signed-off-by: Daniel Vetter
---
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/omapdrm/omap_drv.c | 3 ---
drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 3 ---
drivers/gpu/drm/tegra/dc.c | 1 -
drivers/gpu/drm/tidss/tidss_crtc.c | 3 +--
drivers/gpu/drm/tidss/tidss_kms.c| 4
10 files changed, 9 insertions(+), 26 deletions(-)
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
index 56bd938961ee..f33418d6e1a0 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
@@ -492,10 +492,8 @@ static void komeda_crtc_reset(struct drm_crtc *crtc)
crtc->state = NULL;
state = kzalloc(sizeof(*state), GFP_KERNEL);
- if (state) {
- crtc->state = >base;
- crtc->state->crtc = crtc;
- }
+ if (state)
+ __drm_atomic_helper_crtc_reset(crtc, >base);
}
static struct drm_crtc_state *
@@ -616,7 +614,6 @@ static int komeda_crtc_add(struct komeda_kms_dev *kms,
return err;
drm_crtc_helper_add(crtc, _crtc_helper_funcs);
- drm_crtc_vblank_reset(crtc);
crtc->port = kcrtc->master->of_output_port;
diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
index c2507b7d8512..02904392e370 100644
--- a/drivers/gpu/drm/arm/malidp_drv.c
+++ b/drivers/gpu/drm/arm/malidp_drv.c
@@ -870,7 +870,6 @@ static int malidp_bind(struct device *dev)
drm->irq_enabled = true;
ret = drm_vblank_init(drm, drm->mode_config.num_crtc);
- drm_crtc_vblank_reset(>crtc);
if (ret < 0) {
DRM_ERROR("failed to initialise vblank\n");
goto vblank_fail;
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 10985134ce0b..ce246b96330b 100644
---
