diff mbox series

[v1] drm: Do not allow to set NOFB for active primary plane

Message ID 20190415080010.23466-1-stanislav.lisovskiy@intel.com (mailing list archive)
State New, archived
Headers show
Series [v1] drm: Do not allow to set NOFB for active primary plane | expand

Commit Message

Stanislav Lisovskiy April 15, 2019, 8 a.m. UTC
There was an issue reported from end users, confirmed
also locally that when user executes xrandr --output <some DP>
--rotate left/right, the other eDP screen gets blank after rotation.

Investigation showed that reason was that primary plane
was for some reason disabled, while cursor plane was still enabled.
After some effort it turns out that userspace might wrongly
assign NOFB to active primary plane for some reason.

Then this gets detected in drm_atomic_helper_check_plane_state,
called from ->plane_check and plane gets deactivated, leaving
the screen blank and cursor visible. This can be cured by reboot
or xrandr off/on sequence for that crtc.

This patch is proposal to fix the issue by forbiding fb removal
from active primary plane. If one needs to remove fb plane must be
disabled first.

Not sure if this is correct, however it fixes the issue at least.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110375
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Maarten Lankhorst April 15, 2019, 10:40 a.m. UTC | #1
Op 15-04-2019 om 10:00 schreef Stanislav Lisovskiy:
> There was an issue reported from end users, confirmed
> also locally that when user executes xrandr --output <some DP>
> --rotate left/right, the other eDP screen gets blank after rotation.
>
> Investigation showed that reason was that primary plane
> was for some reason disabled, while cursor plane was still enabled.
> After some effort it turns out that userspace might wrongly
> assign NOFB to active primary plane for some reason.
>
> Then this gets detected in drm_atomic_helper_check_plane_state,
> called from ->plane_check and plane gets deactivated, leaving
> the screen blank and cursor visible. This can be cured by reboot
> or xrandr off/on sequence for that crtc.
>
> This patch is proposal to fix the issue by forbiding fb removal
> from active primary plane. If one needs to remove fb plane must be
> disabled first.
>
> Not sure if this is correct, however it fixes the issue at least.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110375
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> ---
>  drivers/gpu/drm/drm_atomic_uapi.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index ea797d4c82ee..e2f078b302f3 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -229,6 +229,15 @@ drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
>  {
>  	struct drm_plane *plane = plane_state->plane;
>  
> +	if (!fb) {
> +		if (plane->state->visible && plane->type == DRM_PLANE_TYPE_PRIMARY) {
> +			DRM_DEBUG_ATOMIC("Not allowed to set [NOFB] for active"
> +					" primary [PLANE:%d:%s] - disable first",
> +					plane->base.id, plane->name);
> +			return;
> +		}
> +	}
> +
>  	if (fb)
>  		DRM_DEBUG_ATOMIC("Set [FB:%d] for [PLANE:%d:%s] state %p\n",
>  				 fb->base.id, plane->base.id, plane->name,

If userspace asks to disable the primary plane, but not the crtc then that is not an atomic bug. The bug is in the userspace requesting this (Xorg).

If you want to include such a check, the correct place is at the end of drm_atomic_check_only(), after ->atomic_check(), return -EINVAL there.

But such a patch will not be accepted. It's perfectly acceptable to disable the primary plane for whatever reason, and some of our internal tests do so.

~Maarten
Stanislav Lisovskiy April 15, 2019, 11:27 a.m. UTC | #2
On Mon, 2019-04-15 at 12:40 +0200, Maarten Lankhorst wrote:
> Op 15-04-2019 om 10:00 schreef Stanislav Lisovskiy:
> > There was an issue reported from end users, confirmed
> > also locally that when user executes xrandr --output <some DP>
> > --rotate left/right, the other eDP screen gets blank after
> > rotation.
> > 
> > Investigation showed that reason was that primary plane
> > was for some reason disabled, while cursor plane was still enabled.
> > After some effort it turns out that userspace might wrongly
> > assign NOFB to active primary plane for some reason.
> > 
> > Then this gets detected in drm_atomic_helper_check_plane_state,
> > called from ->plane_check and plane gets deactivated, leaving
> > the screen blank and cursor visible. This can be cured by reboot
> > or xrandr off/on sequence for that crtc.
> > 
> > This patch is proposal to fix the issue by forbiding fb removal
> > from active primary plane. If one needs to remove fb plane must be
> > disabled first.
> > 
> > Not sure if this is correct, however it fixes the issue at least.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110375
> > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > ---
> >  drivers/gpu/drm/drm_atomic_uapi.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c
> > b/drivers/gpu/drm/drm_atomic_uapi.c
> > index ea797d4c82ee..e2f078b302f3 100644
> > --- a/drivers/gpu/drm/drm_atomic_uapi.c
> > +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> > @@ -229,6 +229,15 @@ drm_atomic_set_fb_for_plane(struct
> > drm_plane_state *plane_state,
> >  {
> >  	struct drm_plane *plane = plane_state->plane;
> >  
> > +	if (!fb) {
> > +		if (plane->state->visible && plane->type ==
> > DRM_PLANE_TYPE_PRIMARY) {
> > +			DRM_DEBUG_ATOMIC("Not allowed to set [NOFB] for
> > active"
> > +					" primary [PLANE:%d:%s] -
> > disable first",
> > +					plane->base.id, plane->name);
> > +			return;
> > +		}
> > +	}
> > +
> >  	if (fb)
> >  		DRM_DEBUG_ATOMIC("Set [FB:%d] for [PLANE:%d:%s] state
> > %p\n",
> >  				 fb->base.id, plane->base.id, plane-
> > >name,
> 
> If userspace asks to disable the primary plane, but not the crtc then
> that is not an atomic bug. The bug is in the userspace requesting
> this (Xorg).
> 
> If you want to include such a check, the correct place is at the end
> of drm_atomic_check_only(), after ->atomic_check(), return -EINVAL
> there.
> 
> But such a patch will not be accepted. It's perfectly acceptable to
> disable the primary plane for whatever reason, and some of our
> internal tests do so.

Well, yeah that's why I was not quite sure, if this is correct.
However to me the problem seems to be that userspace is disabling
primary plane without realizing it. For example on my skl I see
that drm_atomic_helper_check_plane_state complains that primary
plane has no FB and then disables it.

> 
> ~Maarten
> 
>
Daniel Vetter April 16, 2019, 7:38 a.m. UTC | #3
On Mon, Apr 15, 2019 at 11:27:25AM +0000, Lisovskiy, Stanislav wrote:
> On Mon, 2019-04-15 at 12:40 +0200, Maarten Lankhorst wrote:
> > Op 15-04-2019 om 10:00 schreef Stanislav Lisovskiy:
> > > There was an issue reported from end users, confirmed
> > > also locally that when user executes xrandr --output <some DP>
> > > --rotate left/right, the other eDP screen gets blank after
> > > rotation.
> > > 
> > > Investigation showed that reason was that primary plane
> > > was for some reason disabled, while cursor plane was still enabled.
> > > After some effort it turns out that userspace might wrongly
> > > assign NOFB to active primary plane for some reason.
> > > 
> > > Then this gets detected in drm_atomic_helper_check_plane_state,
> > > called from ->plane_check and plane gets deactivated, leaving
> > > the screen blank and cursor visible. This can be cured by reboot
> > > or xrandr off/on sequence for that crtc.
> > > 
> > > This patch is proposal to fix the issue by forbiding fb removal
> > > from active primary plane. If one needs to remove fb plane must be
> > > disabled first.
> > > 
> > > Not sure if this is correct, however it fixes the issue at least.
> > > 
> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110375
> > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > > ---
> > >  drivers/gpu/drm/drm_atomic_uapi.c | 9 +++++++++
> > >  1 file changed, 9 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c
> > > b/drivers/gpu/drm/drm_atomic_uapi.c
> > > index ea797d4c82ee..e2f078b302f3 100644
> > > --- a/drivers/gpu/drm/drm_atomic_uapi.c
> > > +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> > > @@ -229,6 +229,15 @@ drm_atomic_set_fb_for_plane(struct
> > > drm_plane_state *plane_state,
> > >  {
> > >  	struct drm_plane *plane = plane_state->plane;
> > >  
> > > +	if (!fb) {
> > > +		if (plane->state->visible && plane->type ==
> > > DRM_PLANE_TYPE_PRIMARY) {
> > > +			DRM_DEBUG_ATOMIC("Not allowed to set [NOFB] for
> > > active"
> > > +					" primary [PLANE:%d:%s] -
> > > disable first",
> > > +					plane->base.id, plane->name);
> > > +			return;
> > > +		}
> > > +	}
> > > +
> > >  	if (fb)
> > >  		DRM_DEBUG_ATOMIC("Set [FB:%d] for [PLANE:%d:%s] state
> > > %p\n",
> > >  				 fb->base.id, plane->base.id, plane-
> > > >name,
> > 
> > If userspace asks to disable the primary plane, but not the crtc then
> > that is not an atomic bug. The bug is in the userspace requesting
> > this (Xorg).
> > 
> > If you want to include such a check, the correct place is at the end
> > of drm_atomic_check_only(), after ->atomic_check(), return -EINVAL
> > there.
> > 
> > But such a patch will not be accepted. It's perfectly acceptable to
> > disable the primary plane for whatever reason, and some of our
> > internal tests do so.
> 
> Well, yeah that's why I was not quite sure, if this is correct.
> However to me the problem seems to be that userspace is disabling
> primary plane without realizing it. For example on my skl I see
> that drm_atomic_helper_check_plane_state complains that primary
> plane has no FB and then disables it.

Yeah we need to figure out where this is coming from. Is this with sna or
-modesetting or something else?
-Daniel
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index ea797d4c82ee..e2f078b302f3 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -229,6 +229,15 @@  drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
 {
 	struct drm_plane *plane = plane_state->plane;
 
+	if (!fb) {
+		if (plane->state->visible && plane->type == DRM_PLANE_TYPE_PRIMARY) {
+			DRM_DEBUG_ATOMIC("Not allowed to set [NOFB] for active"
+					" primary [PLANE:%d:%s] - disable first",
+					plane->base.id, plane->name);
+			return;
+		}
+	}
+
 	if (fb)
 		DRM_DEBUG_ATOMIC("Set [FB:%d] for [PLANE:%d:%s] state %p\n",
 				 fb->base.id, plane->base.id, plane->name,