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)
>
