[PATCH] drm/amd/display: Fix overlay validation by considering cursors

[PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Rodrigo Siqueira]

A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
fixed it in the commit:

 drm/amd/display: Fix two cursor duplication when using overlay
 (read the commit message for more details)

After this change, we noticed that some IGT subtests related to
kms_plane and kms_plane_scaling started to fail. After investigating
this issue, we noticed that all subtests that fail have a primary plane
covering the overlay plane, which is currently rejected by amdgpu dm.
Fail those IGT tests highlight that our verification was too broad and
compromises the overlay usage in our drive. This patch fixes this issue
by ensuring that we only reject commits where the primary plane is not
fully covered by the overlay when the cursor hardware is enabled. With
this fix, all IGT tests start to pass again, which means our overlay
support works as expected.

Cc: Tianci.Yin <tianci.yin@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Nicholas Choi <nicholas.choi@amd.com>
Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Cc: Mark Yacoub <markyacoub@google.com>
Cc: Daniel Wheeler <daniel.wheeler@amd.com>

Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index ccd67003b120..9c2537a17a7b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
 	int i;
 	struct drm_plane *plane;
 	struct drm_plane_state *old_plane_state, *new_plane_state;
-	struct drm_plane_state *primary_state, *overlay_state = NULL;
+	struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
 
 	/* Check if primary plane is contained inside overlay */
 	for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
@@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
 	if (!primary_state->crtc)
 		return 0;
 
+	/* check if cursor plane is enabled */
+	cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
+	if (IS_ERR(cursor_state))
+		return PTR_ERR(cursor_state);
+
+	if (drm_atomic_plane_disabling(plane->state, cursor_state))
+		return 0;
+
 	/* Perform the bounds check to ensure the overlay plane covers the primary */
 	if (primary_state->crtc_x < overlay_state->crtc_x ||
 	    primary_state->crtc_y < overlay_state->crtc_y ||
-- 
2.25.1

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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Mark Yacoub]

On Fri, May 14, 2021 at 7:48 AM Rodrigo Siqueira
<Rodrigo.Siqueira@amd.com> wrote:
>
> A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> fixed it in the commit:
>
>  drm/amd/display: Fix two cursor duplication when using overlay
>  (read the commit message for more details)
>
> After this change, we noticed that some IGT subtests related to
> kms_plane and kms_plane_scaling started to fail. After investigating
> this issue, we noticed that all subtests that fail have a primary plane
> covering the overlay plane, which is currently rejected by amdgpu dm.
> Fail those IGT tests highlight that our verification was too broad and
> compromises the overlay usage in our drive. This patch fixes this issue
nit: driver*
> by ensuring that we only reject commits where the primary plane is not
> fully covered by the overlay when the cursor hardware is enabled. With
> this fix, all IGT tests start to pass again, which means our overlay
> support works as expected.
>
> Cc: Tianci.Yin <tianci.yin@amd.com>
> Cc: Harry Wentland <harry.wentland@amd.com>
> Cc: Nicholas Choi <nicholas.choi@amd.com>
> Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> Cc: Mark Yacoub <markyacoub@google.com>
> Cc: Daniel Wheeler <daniel.wheeler@amd.com>
>
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index ccd67003b120..9c2537a17a7b 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
>         int i;
>         struct drm_plane *plane;
>         struct drm_plane_state *old_plane_state, *new_plane_state;
> -       struct drm_plane_state *primary_state, *overlay_state = NULL;
> +       struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
>
>         /* Check if primary plane is contained inside overlay */
>         for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
>         if (!primary_state->crtc)
>                 return 0;
>
> +       /* check if cursor plane is enabled */
> +       cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> +       if (IS_ERR(cursor_state))
> +               return PTR_ERR(cursor_state);
> +
> +       if (drm_atomic_plane_disabling(plane->state, cursor_state))
> +               return 0;
> +
>         /* Perform the bounds check to ensure the overlay plane covers the primary */
>         if (primary_state->crtc_x < overlay_state->crtc_x ||
>             primary_state->crtc_y < overlay_state->crtc_y ||
> --
> 2.25.1
>
Happy this was caught earlier. Would not have been fun debugging it on
Chrome haha.
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RE: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Wheeler, Daniel]

[AMD Public Use]

The tests that failed previously for me were:
amdgpu/amd_plane -> mpo-swizzle-toggle
kms_atomic -> plane-overlay-legacy
kms_plane -> plane-position-covered-pipe-a-planes
kms_plane -> plane-position-covered-pipe-c-planes
kms_plane -> plane-position-hole-dpms-pipe-a-planes
kms_plane -> plane-position-hole-dpms-pipe-c-planes
kms_plane -> plane-position-hole-pipe-a-planes
kms_plane -> plane-position-hole-pipe-c-planes
kms_plane_scaling -> pipe-a-plane-scaling
kms_plane_scaling -> pipe-c-plane-scaling

After testing this patch on a HP Envy 360, with Ryzen 5 4500u, a Sapphire Pulse RX5700XT, and an AMD Reference RX6800, these tests all now pass. 



Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>

 
Thank you,
 
Dan Wheeler
Technologist  |  AMD
SW Display
------------------------------------------------------------------------------------------------------------------
1 Commerce Valley Dr E, Thornhill, ON L3T 7X6
Facebook |  Twitter |  amd.com  

Thank you,

Dan Wheeler
Technologist  |  AMD
SW Display
O +(1) 905-882-2600 ext. 74665
------------------------------------------------------------------------------------------------------------------
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-----Original Message-----
From: Siqueira, Rodrigo <Rodrigo.Siqueira@amd.com> 
Sent: May 14, 2021 7:48 AM
To: amd-gfx@lists.freedesktop.org
Cc: Yin, Tianci (Rico) <Tianci.Yin@amd.com>; Wentland, Harry <Harry.Wentland@amd.com>; Choi, Nicholas <Nicholas.Choi@amd.com>; Lakha, Bhawanpreet <Bhawanpreet.Lakha@amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com>; Mark Yacoub <markyacoub@google.com>; Wheeler, Daniel <Daniel.Wheeler@amd.com>
Subject: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

A few weeks ago, we saw a two cursor issue in a ChromeOS system. We fixed it in the commit:

 drm/amd/display: Fix two cursor duplication when using overlay  (read the commit message for more details)

After this change, we noticed that some IGT subtests related to kms_plane and kms_plane_scaling started to fail. After investigating this issue, we noticed that all subtests that fail have a primary plane covering the overlay plane, which is currently rejected by amdgpu dm.
Fail those IGT tests highlight that our verification was too broad and compromises the overlay usage in our drive. This patch fixes this issue by ensuring that we only reject commits where the primary plane is not fully covered by the overlay when the cursor hardware is enabled. With this fix, all IGT tests start to pass again, which means our overlay support works as expected.

Cc: Tianci.Yin <tianci.yin@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Nicholas Choi <nicholas.choi@amd.com>
Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Cc: Mark Yacoub <markyacoub@google.com>
Cc: Daniel Wheeler <daniel.wheeler@amd.com>

Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index ccd67003b120..9c2537a17a7b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
 	int i;
 	struct drm_plane *plane;
 	struct drm_plane_state *old_plane_state, *new_plane_state;
-	struct drm_plane_state *primary_state, *overlay_state = NULL;
+	struct drm_plane_state *primary_state, *cursor_state, *overlay_state = 
+NULL;
 
 	/* Check if primary plane is contained inside overlay */
 	for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) { @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
 	if (!primary_state->crtc)
 		return 0;
 
+	/* check if cursor plane is enabled */
+	cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
+	if (IS_ERR(cursor_state))
+		return PTR_ERR(cursor_state);
+
+	if (drm_atomic_plane_disabling(plane->state, cursor_state))
+		return 0;
+
 	/* Perform the bounds check to ensure the overlay plane covers the primary */
 	if (primary_state->crtc_x < overlay_state->crtc_x ||
 	    primary_state->crtc_y < overlay_state->crtc_y ||
--
2.25.1
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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Harry Wentland]

On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> fixed it in the commit:
> 
>  drm/amd/display: Fix two cursor duplication when using overlay
>  (read the commit message for more details)
> 
> After this change, we noticed that some IGT subtests related to
> kms_plane and kms_plane_scaling started to fail. After investigating
> this issue, we noticed that all subtests that fail have a primary plane
> covering the overlay plane, which is currently rejected by amdgpu dm.
> Fail those IGT tests highlight that our verification was too broad and
> compromises the overlay usage in our drive. This patch fixes this issue
> by ensuring that we only reject commits where the primary plane is not
> fully covered by the overlay when the cursor hardware is enabled. With
> this fix, all IGT tests start to pass again, which means our overlay
> support works as expected.
> 
> Cc: Tianci.Yin <tianci.yin@amd.com>
> Cc: Harry Wentland <harry.wentland@amd.com>
> Cc: Nicholas Choi <nicholas.choi@amd.com>
> Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> Cc: Mark Yacoub <markyacoub@google.com>
> Cc: Daniel Wheeler <daniel.wheeler@amd.com>
> 
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index ccd67003b120..9c2537a17a7b 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
>  	int i;
>  	struct drm_plane *plane;
>  	struct drm_plane_state *old_plane_state, *new_plane_state;
> -	struct drm_plane_state *primary_state, *overlay_state = NULL;
> +	struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
>  
>  	/* Check if primary plane is contained inside overlay */
>  	for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
>  	if (!primary_state->crtc)
>  		return 0;
>  
> +	/* check if cursor plane is enabled */
> +	cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> +	if (IS_ERR(cursor_state))
> +		return PTR_ERR(cursor_state);
> +
> +	if (drm_atomic_plane_disabling(plane->state, cursor_state))
> +		return 0;
> +

I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
based solely on whether a cursor is enabled or not.

Harry

>  	/* Perform the bounds check to ensure the overlay plane covers the primary */
>  	if (primary_state->crtc_x < overlay_state->crtc_x ||
>  	    primary_state->crtc_y < overlay_state->crtc_y ||
> 

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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Mark Yacoub]

On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland@amd.com> wrote:
>
> On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> > A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> > fixed it in the commit:
> >
> >  drm/amd/display: Fix two cursor duplication when using overlay
> >  (read the commit message for more details)
> >
> > After this change, we noticed that some IGT subtests related to
> > kms_plane and kms_plane_scaling started to fail. After investigating
> > this issue, we noticed that all subtests that fail have a primary plane
> > covering the overlay plane, which is currently rejected by amdgpu dm.
> > Fail those IGT tests highlight that our verification was too broad and
> > compromises the overlay usage in our drive. This patch fixes this issue
> > by ensuring that we only reject commits where the primary plane is not
> > fully covered by the overlay when the cursor hardware is enabled. With
> > this fix, all IGT tests start to pass again, which means our overlay
> > support works as expected.
> >
> > Cc: Tianci.Yin <tianci.yin@amd.com>
> > Cc: Harry Wentland <harry.wentland@amd.com>
> > Cc: Nicholas Choi <nicholas.choi@amd.com>
> > Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> > Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> > Cc: Mark Yacoub <markyacoub@google.com>
> > Cc: Daniel Wheeler <daniel.wheeler@amd.com>
> >
> > Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> > ---
> >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index ccd67003b120..9c2537a17a7b 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
> >       int i;
> >       struct drm_plane *plane;
> >       struct drm_plane_state *old_plane_state, *new_plane_state;
> > -     struct drm_plane_state *primary_state, *overlay_state = NULL;
> > +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
> >
> >       /* Check if primary plane is contained inside overlay */
> >       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> > @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
> >       if (!primary_state->crtc)
> >               return 0;
> >
> > +     /* check if cursor plane is enabled */
> > +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> > +     if (IS_ERR(cursor_state))
> > +             return PTR_ERR(cursor_state);
> > +
> > +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
> > +             return 0;
> > +
>
> I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
> based solely on whether a cursor is enabled or not.
>
> Harry
>
> >       /* Perform the bounds check to ensure the overlay plane covers the primary */
> >       if (primary_state->crtc_x < overlay_state->crtc_x ||
> >           primary_state->crtc_y < overlay_state->crtc_y ||
> >
>
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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Mark Yacoub]

On Fri, May 14, 2021 at 12:31 PM Mark Yacoub <markyacoub@google.com> wrote:
>
> On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland@amd.com> wrote:
> >
> > On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> > > A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> > > fixed it in the commit:
> > >
> > >  drm/amd/display: Fix two cursor duplication when using overlay
> > >  (read the commit message for more details)
> > >
> > > After this change, we noticed that some IGT subtests related to
> > > kms_plane and kms_plane_scaling started to fail. After investigating
> > > this issue, we noticed that all subtests that fail have a primary plane
> > > covering the overlay plane, which is currently rejected by amdgpu dm.
> > > Fail those IGT tests highlight that our verification was too broad and
> > > compromises the overlay usage in our drive. This patch fixes this issue
nit: s/drive/driver?
> > > by ensuring that we only reject commits where the primary plane is not
> > > fully covered by the overlay when the cursor hardware is enabled. With
> > > this fix, all IGT tests start to pass again, which means our overlay
> > > support works as expected.
> > >
> > > Cc: Tianci.Yin <tianci.yin@amd.com>
> > > Cc: Harry Wentland <harry.wentland@amd.com>
> > > Cc: Nicholas Choi <nicholas.choi@amd.com>
> > > Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> > > Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> > > Cc: Mark Yacoub <markyacoub@google.com>
> > > Cc: Daniel Wheeler <daniel.wheeler@amd.com>
> > >
> > > Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> > > ---
> > >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
> > >  1 file changed, 9 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > index ccd67003b120..9c2537a17a7b 100644
> > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
> > >       int i;
> > >       struct drm_plane *plane;
> > >       struct drm_plane_state *old_plane_state, *new_plane_state;
> > > -     struct drm_plane_state *primary_state, *overlay_state = NULL;
> > > +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
> > >
> > >       /* Check if primary plane is contained inside overlay */
> > >       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> > > @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
> > >       if (!primary_state->crtc)
> > >               return 0;
> > >
> > > +     /* check if cursor plane is enabled */
> > > +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> > > +     if (IS_ERR(cursor_state))
> > > +             return PTR_ERR(cursor_state);
> > > +
> > > +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
> > > +             return 0;
> > > +
> >
> > I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
> > based solely on whether a cursor is enabled or not.
For context: To use overlays (the old/current async way), Chrome tests
if an overlay strategy will work by doing an atomic commit with a TEST
flag to check if the combination would work. If it works, it flags
this planes configuration as valid. As it's valid, it performs an
atomic page flip (which could also include the cursor).
So to Harry's point, you would pass an atomic test but fail on an
atomic page flip with the exact same configuration that's been flagged
as valid. Failing a pageflip causes Chrome to crash (Reset the GPU
process cause something went horribly wrong when it shouldn't).
> >
> > Harry
> >
> > >       /* Perform the bounds check to ensure the overlay plane covers the primary */
> > >       if (primary_state->crtc_x < overlay_state->crtc_x ||
> > >           primary_state->crtc_y < overlay_state->crtc_y ||
> > >
> >
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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Rodrigo Siqueira]

[-- Attachment #1.1: Type: text/plain, Size: 5178 bytes --]

On 05/14, Mark Yacoub wrote:
> On Fri, May 14, 2021 at 12:31 PM Mark Yacoub <markyacoub@google.com> wrote:
> >
> > On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland@amd.com> wrote:
> > >
> > > On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> > > > A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> > > > fixed it in the commit:
> > > >
> > > >  drm/amd/display: Fix two cursor duplication when using overlay
> > > >  (read the commit message for more details)
> > > >
> > > > After this change, we noticed that some IGT subtests related to
> > > > kms_plane and kms_plane_scaling started to fail. After investigating
> > > > this issue, we noticed that all subtests that fail have a primary plane
> > > > covering the overlay plane, which is currently rejected by amdgpu dm.
> > > > Fail those IGT tests highlight that our verification was too broad and
> > > > compromises the overlay usage in our drive. This patch fixes this issue
> nit: s/drive/driver?
> > > > by ensuring that we only reject commits where the primary plane is not
> > > > fully covered by the overlay when the cursor hardware is enabled. With
> > > > this fix, all IGT tests start to pass again, which means our overlay
> > > > support works as expected.
> > > >
> > > > Cc: Tianci.Yin <tianci.yin@amd.com>
> > > > Cc: Harry Wentland <harry.wentland@amd.com>
> > > > Cc: Nicholas Choi <nicholas.choi@amd.com>
> > > > Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> > > > Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> > > > Cc: Mark Yacoub <markyacoub@google.com>
> > > > Cc: Daniel Wheeler <daniel.wheeler@amd.com>
> > > >
> > > > Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> > > > ---
> > > >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
> > > >  1 file changed, 9 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > > index ccd67003b120..9c2537a17a7b 100644
> > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > > @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
> > > >       int i;
> > > >       struct drm_plane *plane;
> > > >       struct drm_plane_state *old_plane_state, *new_plane_state;
> > > > -     struct drm_plane_state *primary_state, *overlay_state = NULL;
> > > > +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
> > > >
> > > >       /* Check if primary plane is contained inside overlay */
> > > >       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> > > > @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
> > > >       if (!primary_state->crtc)
> > > >               return 0;
> > > >
> > > > +     /* check if cursor plane is enabled */
> > > > +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> > > > +     if (IS_ERR(cursor_state))
> > > > +             return PTR_ERR(cursor_state);
> > > > +
> > > > +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
> > > > +             return 0;
> > > > +
> > >
> > > I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
> > > based solely on whether a cursor is enabled or not.
> For context: To use overlays (the old/current async way), Chrome tests
> if an overlay strategy will work by doing an atomic commit with a TEST
> flag to check if the combination would work. If it works, it flags
> this planes configuration as valid. As it's valid, it performs an
> atomic page flip (which could also include the cursor).
> So to Harry's point, you would pass an atomic test but fail on an
> atomic page flip with the exact same configuration that's been flagged
> as valid. Failing a pageflip causes Chrome to crash (Reset the GPU
> process cause something went horribly wrong when it shouldn't).

Hi Mark and Sean,

I don't know if I fully comprehended the scenario which in my patch
might cause a ChromeOS crash, but this is what I understood:

There is a chance that we pass the atomic check
(DRM_MODE_ATOMIC_TEST_ONLY - TEST) but fails in the atomic page flip
because, after use TEST, the compositor might slightly change the commit
config by adding the cursor. The reason behind that came from the
assumption that adds the cursor in the atomic commit config after the
test is harmless. Is my understand correct? Please, correct me if I'm
wrong.

If the above reasoning is correct, I think the compositor should not
assume anything extra from what it got from the atomic check.

Best Regards,
Siqueira

> > >
> > > Harry
> > >
> > > >       /* Perform the bounds check to ensure the overlay plane covers the primary */
> > > >       if (primary_state->crtc_x < overlay_state->crtc_x ||
> > > >           primary_state->crtc_y < overlay_state->crtc_y ||
> > > >
> > >

-- 
Rodrigo Siqueira
https://siqueira.tech

[-- Attachment #1.2: signature.asc --]
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[-- Attachment #2: Type: text/plain, Size: 154 bytes --]

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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Sean Paul]

On Tue, May 18, 2021 at 2:58 PM Rodrigo Siqueira
<Rodrigo.Siqueira@amd.com> wrote:
>
> On 05/14, Mark Yacoub wrote:
> > On Fri, May 14, 2021 at 12:31 PM Mark Yacoub <markyacoub@google.com> wrote:
> > >
> > > On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland@amd.com> wrote:
> > > >
> > > > On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> > > > > A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> > > > > fixed it in the commit:
> > > > >
> > > > >  drm/amd/display: Fix two cursor duplication when using overlay
> > > > >  (read the commit message for more details)
> > > > >
> > > > > After this change, we noticed that some IGT subtests related to
> > > > > kms_plane and kms_plane_scaling started to fail. After investigating
> > > > > this issue, we noticed that all subtests that fail have a primary plane
> > > > > covering the overlay plane, which is currently rejected by amdgpu dm.
> > > > > Fail those IGT tests highlight that our verification was too broad and
> > > > > compromises the overlay usage in our drive. This patch fixes this issue
> > nit: s/drive/driver?
> > > > > by ensuring that we only reject commits where the primary plane is not
> > > > > fully covered by the overlay when the cursor hardware is enabled. With
> > > > > this fix, all IGT tests start to pass again, which means our overlay
> > > > > support works as expected.
> > > > >
> > > > > Cc: Tianci.Yin <tianci.yin@amd.com>
> > > > > Cc: Harry Wentland <harry.wentland@amd.com>
> > > > > Cc: Nicholas Choi <nicholas.choi@amd.com>
> > > > > Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> > > > > Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> > > > > Cc: Mark Yacoub <markyacoub@google.com>
> > > > > Cc: Daniel Wheeler <daniel.wheeler@amd.com>
> > > > >
> > > > > Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> > > > > ---
> > > > >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
> > > > >  1 file changed, 9 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > > > index ccd67003b120..9c2537a17a7b 100644
> > > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > > > @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
> > > > >       int i;
> > > > >       struct drm_plane *plane;
> > > > >       struct drm_plane_state *old_plane_state, *new_plane_state;
> > > > > -     struct drm_plane_state *primary_state, *overlay_state = NULL;
> > > > > +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
> > > > >
> > > > >       /* Check if primary plane is contained inside overlay */
> > > > >       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> > > > > @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
> > > > >       if (!primary_state->crtc)
> > > > >               return 0;
> > > > >
> > > > > +     /* check if cursor plane is enabled */
> > > > > +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> > > > > +     if (IS_ERR(cursor_state))
> > > > > +             return PTR_ERR(cursor_state);
> > > > > +
> > > > > +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
> > > > > +             return 0;
> > > > > +
> > > >
> > > > I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
> > > > based solely on whether a cursor is enabled or not.
> > For context: To use overlays (the old/current async way), Chrome tests
> > if an overlay strategy will work by doing an atomic commit with a TEST
> > flag to check if the combination would work. If it works, it flags
> > this planes configuration as valid. As it's valid, it performs an
> > atomic page flip (which could also include the cursor).
> > So to Harry's point, you would pass an atomic test but fail on an
> > atomic page flip with the exact same configuration that's been flagged
> > as valid. Failing a pageflip causes Chrome to crash (Reset the GPU
> > process cause something went horribly wrong when it shouldn't).
>
> Hi Mark and Sean,
>
> I don't know if I fully comprehended the scenario which in my patch
> might cause a ChromeOS crash, but this is what I understood:
>

Chrome compositor only does an atomic test when the layout geometry
changes (ie: plane is added/removed/resized/moved). This does not take
into consideration the cursor. Once the atomic test has been validated
for a given layout geometry (set of planes/fbs along with their sizes
and locations), Chrome assumes this will continue to be valid.

So the situation I'm envisioning is if the cursor is hidden, an
overlay-based strategy will pass in the kernel. If at any time the
cursor becomes visible, the kernel will start failing commits which
causes Chrome's GPU process to crash.

In general I'm uneasy with using the cursor in the atomic check since
it feels like it could be racy independent of the issue above. I
haven't dove into the helper code enough to prove it, just a
spidey-sense.

Sean

> There is a chance that we pass the atomic check
> (DRM_MODE_ATOMIC_TEST_ONLY - TEST) but fails in the atomic page flip
> because, after use TEST, the compositor might slightly change the commit
> config by adding the cursor. The reason behind that came from the
> assumption that adds the cursor in the atomic commit config after the
> test is harmless. Is my understand correct? Please, correct me if I'm
> wrong.
>
> If the above reasoning is correct, I think the compositor should not
> assume anything extra from what it got from the atomic check.
>
> Best Regards,
> Siqueira
>
> > > >
> > > > Harry
> > > >
> > > > >       /* Perform the bounds check to ensure the overlay plane covers the primary */
> > > > >       if (primary_state->crtc_x < overlay_state->crtc_x ||
> > > > >           primary_state->crtc_y < overlay_state->crtc_y ||
> > > > >
> > > >
>
> --
> Rodrigo Siqueira
> https://siqueira.tech
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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Harry Wentland]

On 2021-06-07 2:19 p.m., Sean Paul wrote:
> On Tue, May 18, 2021 at 2:58 PM Rodrigo Siqueira
> <Rodrigo.Siqueira@amd.com> wrote:
>>
>> On 05/14, Mark Yacoub wrote:
>>> On Fri, May 14, 2021 at 12:31 PM Mark Yacoub <markyacoub@google.com> wrote:
>>>>
>>>> On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland@amd.com> wrote:
>>>>>
>>>>> On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
>>>>>> A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
>>>>>> fixed it in the commit:
>>>>>>
>>>>>>  drm/amd/display: Fix two cursor duplication when using overlay
>>>>>>  (read the commit message for more details)
>>>>>>
>>>>>> After this change, we noticed that some IGT subtests related to
>>>>>> kms_plane and kms_plane_scaling started to fail. After investigating
>>>>>> this issue, we noticed that all subtests that fail have a primary plane
>>>>>> covering the overlay plane, which is currently rejected by amdgpu dm.
>>>>>> Fail those IGT tests highlight that our verification was too broad and
>>>>>> compromises the overlay usage in our drive. This patch fixes this issue
>>> nit: s/drive/driver?
>>>>>> by ensuring that we only reject commits where the primary plane is not
>>>>>> fully covered by the overlay when the cursor hardware is enabled. With
>>>>>> this fix, all IGT tests start to pass again, which means our overlay
>>>>>> support works as expected.
>>>>>>
>>>>>> Cc: Tianci.Yin <tianci.yin@amd.com>
>>>>>> Cc: Harry Wentland <harry.wentland@amd.com>
>>>>>> Cc: Nicholas Choi <nicholas.choi@amd.com>
>>>>>> Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
>>>>>> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
>>>>>> Cc: Mark Yacoub <markyacoub@google.com>
>>>>>> Cc: Daniel Wheeler <daniel.wheeler@amd.com>
>>>>>>
>>>>>> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
>>>>>> ---
>>>>>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
>>>>>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>>> index ccd67003b120..9c2537a17a7b 100644
>>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>>> @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
>>>>>>       int i;
>>>>>>       struct drm_plane *plane;
>>>>>>       struct drm_plane_state *old_plane_state, *new_plane_state;
>>>>>> -     struct drm_plane_state *primary_state, *overlay_state = NULL;
>>>>>> +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
>>>>>>
>>>>>>       /* Check if primary plane is contained inside overlay */
>>>>>>       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
>>>>>> @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
>>>>>>       if (!primary_state->crtc)
>>>>>>               return 0;
>>>>>>
>>>>>> +     /* check if cursor plane is enabled */
>>>>>> +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
>>>>>> +     if (IS_ERR(cursor_state))
>>>>>> +             return PTR_ERR(cursor_state);
>>>>>> +
>>>>>> +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
>>>>>> +             return 0;
>>>>>> +
>>>>>
>>>>> I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
>>>>> based solely on whether a cursor is enabled or not.
>>> For context: To use overlays (the old/current async way), Chrome tests
>>> if an overlay strategy will work by doing an atomic commit with a TEST
>>> flag to check if the combination would work. If it works, it flags
>>> this planes configuration as valid. As it's valid, it performs an
>>> atomic page flip (which could also include the cursor).
>>> So to Harry's point, you would pass an atomic test but fail on an
>>> atomic page flip with the exact same configuration that's been flagged
>>> as valid. Failing a pageflip causes Chrome to crash (Reset the GPU
>>> process cause something went horribly wrong when it shouldn't).
>>
>> Hi Mark and Sean,
>>
>> I don't know if I fully comprehended the scenario which in my patch
>> might cause a ChromeOS crash, but this is what I understood:
>>
> 
> Chrome compositor only does an atomic test when the layout geometry
> changes (ie: plane is added/removed/resized/moved). This does not take
> into consideration the cursor. Once the atomic test has been validated
> for a given layout geometry (set of planes/fbs along with their sizes
> and locations), Chrome assumes this will continue to be valid.
> 
> So the situation I'm envisioning is if the cursor is hidden, an
> overlay-based strategy will pass in the kernel. If at any time the
> cursor becomes visible, the kernel will start failing commits which
> causes Chrome's GPU process to crash.
> 
> In general I'm uneasy with using the cursor in the atomic check since
> it feels like it could be racy independent of the issue above. I
> haven't dove into the helper code enough to prove it, just a
> spidey-sense.
> 

Isn't the cursor supposed to be just another plane? If so, shouldn't
adding/removing the cursor trigger an atomic test?

Is Chrome's compositor doing cursor update through legacy IOCTLs or
through the ATOMIC IOCTL?

Thanks,
Harry

> Sean
> 
>> There is a chance that we pass the atomic check
>> (DRM_MODE_ATOMIC_TEST_ONLY - TEST) but fails in the atomic page flip
>> because, after use TEST, the compositor might slightly change the commit
>> config by adding the cursor. The reason behind that came from the
>> assumption that adds the cursor in the atomic commit config after the
>> test is harmless. Is my understand correct? Please, correct me if I'm
>> wrong.
>>
>> If the above reasoning is correct, I think the compositor should not
>> assume anything extra from what it got from the atomic check.
>>
>> Best Regards,
>> Siqueira
>>
>>>>>
>>>>> Harry
>>>>>
>>>>>>       /* Perform the bounds check to ensure the overlay plane covers the primary */
>>>>>>       if (primary_state->crtc_x < overlay_state->crtc_x ||
>>>>>>           primary_state->crtc_y < overlay_state->crtc_y ||
>>>>>>
>>>>>
>>
>> --
>> Rodrigo Siqueira
>> https://siqueira.tech/>
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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Sean Paul]

[-- Attachment #1.1: Type: text/plain, Size: 6878 bytes --]

On Mon, Jun 7, 2021 at 2:37 PM Harry Wentland <harry.wentland@amd.com>
wrote:

> On 2021-06-07 2:19 p.m., Sean Paul wrote:
> > On Tue, May 18, 2021 at 2:58 PM Rodrigo Siqueira
> > <Rodrigo.Siqueira@amd.com> wrote:
> >>
> >> On 05/14, Mark Yacoub wrote:
> >>> On Fri, May 14, 2021 at 12:31 PM Mark Yacoub <markyacoub@google.com>
> wrote:
> >>>>
> >>>> On Fri, May 14, 2021 at 11:28 AM Harry Wentland <
> harry.wentland@amd.com> wrote:
> >>>>>
> >>>>> On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> >>>>>> A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> >>>>>> fixed it in the commit:
> >>>>>>
> >>>>>>  drm/amd/display: Fix two cursor duplication when using overlay
> >>>>>>  (read the commit message for more details)
> >>>>>>
> >>>>>> After this change, we noticed that some IGT subtests related to
> >>>>>> kms_plane and kms_plane_scaling started to fail. After investigating
> >>>>>> this issue, we noticed that all subtests that fail have a primary
> plane
> >>>>>> covering the overlay plane, which is currently rejected by amdgpu
> dm.
> >>>>>> Fail those IGT tests highlight that our verification was too broad
> and
> >>>>>> compromises the overlay usage in our drive. This patch fixes this
> issue
> >>> nit: s/drive/driver?
> >>>>>> by ensuring that we only reject commits where the primary plane is
> not
> >>>>>> fully covered by the overlay when the cursor hardware is enabled.
> With
> >>>>>> this fix, all IGT tests start to pass again, which means our overlay
> >>>>>> support works as expected.
> >>>>>>
> >>>>>> Cc: Tianci.Yin <tianci.yin@amd.com>
> >>>>>> Cc: Harry Wentland <harry.wentland@amd.com>
> >>>>>> Cc: Nicholas Choi <nicholas.choi@amd.com>
> >>>>>> Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
> >>>>>> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
> >>>>>> Cc: Mark Yacoub <markyacoub@google.com>
> >>>>>> Cc: Daniel Wheeler <daniel.wheeler@amd.com>
> >>>>>>
> >>>>>> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> >>>>>> ---
> >>>>>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
> >>>>>>  1 file changed, 9 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> >>>>>> index ccd67003b120..9c2537a17a7b 100644
> >>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> >>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> >>>>>> @@ -10067,7 +10067,7 @@ static int validate_overlay(struct
> drm_atomic_state *state)
> >>>>>>       int i;
> >>>>>>       struct drm_plane *plane;
> >>>>>>       struct drm_plane_state *old_plane_state, *new_plane_state;
> >>>>>> -     struct drm_plane_state *primary_state, *overlay_state = NULL;
> >>>>>> +     struct drm_plane_state *primary_state, *cursor_state,
> *overlay_state = NULL;
> >>>>>>
> >>>>>>       /* Check if primary plane is contained inside overlay */
> >>>>>>       for_each_oldnew_plane_in_state_reverse(state, plane,
> old_plane_state, new_plane_state, i) {
> >>>>>> @@ -10097,6 +10097,14 @@ static int validate_overlay(struct
> drm_atomic_state *state)
> >>>>>>       if (!primary_state->crtc)
> >>>>>>               return 0;
> >>>>>>
> >>>>>> +     /* check if cursor plane is enabled */
> >>>>>> +     cursor_state = drm_atomic_get_plane_state(state,
> overlay_state->crtc->cursor);
> >>>>>> +     if (IS_ERR(cursor_state))
> >>>>>> +             return PTR_ERR(cursor_state);
> >>>>>> +
> >>>>>> +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
> >>>>>> +             return 0;
> >>>>>> +
> >>>>>
> >>>>> I thought this breaks Chrome's compositor since it can't handle an
> atomic commit rejection
> >>>>> based solely on whether a cursor is enabled or not.
> >>> For context: To use overlays (the old/current async way), Chrome tests
> >>> if an overlay strategy will work by doing an atomic commit with a TEST
> >>> flag to check if the combination would work. If it works, it flags
> >>> this planes configuration as valid. As it's valid, it performs an
> >>> atomic page flip (which could also include the cursor).
> >>> So to Harry's point, you would pass an atomic test but fail on an
> >>> atomic page flip with the exact same configuration that's been flagged
> >>> as valid. Failing a pageflip causes Chrome to crash (Reset the GPU
> >>> process cause something went horribly wrong when it shouldn't).
> >>
> >> Hi Mark and Sean,
> >>
> >> I don't know if I fully comprehended the scenario which in my patch
> >> might cause a ChromeOS crash, but this is what I understood:
> >>
> >
> > Chrome compositor only does an atomic test when the layout geometry
> > changes (ie: plane is added/removed/resized/moved). This does not take
> > into consideration the cursor. Once the atomic test has been validated
> > for a given layout geometry (set of planes/fbs along with their sizes
> > and locations), Chrome assumes this will continue to be valid.
> >
> > So the situation I'm envisioning is if the cursor is hidden, an
> > overlay-based strategy will pass in the kernel. If at any time the
> > cursor becomes visible, the kernel will start failing commits which
> > causes Chrome's GPU process to crash.
> >
> > In general I'm uneasy with using the cursor in the atomic check since
> > it feels like it could be racy independent of the issue above. I
> > haven't dove into the helper code enough to prove it, just a
> > spidey-sense.
> >
>
> Isn't the cursor supposed to be just another plane? If so, shouldn't
> adding/removing the cursor trigger an atomic test?
>
>
Chrome is using legacy cursor.

Yes it will trigger an atomic test in the kernel, and that atomic test will
fail. Unfortunately Chrome does not expect a failure so it will crash.

Sean


Is Chrome's compositor doing cursor update through legacy IOCTLs or
> through the ATOMIC IOCTL?
>
> Thanks,
> Harry
>
> > Sean
> >
> >> There is a chance that we pass the atomic check
> >> (DRM_MODE_ATOMIC_TEST_ONLY - TEST) but fails in the atomic page flip
> >> because, after use TEST, the compositor might slightly change the commit
> >> config by adding the cursor. The reason behind that came from the
> >> assumption that adds the cursor in the atomic commit config after the
> >> test is harmless. Is my understand correct? Please, correct me if I'm
> >> wrong.
> >>
> >> If the above reasoning is correct, I think the compositor should not
> >> assume anything extra from what it got from the atomic check.
> >>
> >> Best Regards,
> >> Siqueira
> >>
> >>>>>
> >>>>> Harry
> >>>>>
> >>>>>>       /* Perform the bounds check to ensure the overlay plane
> covers the primary */
> >>>>>>       if (primary_state->crtc_x < overlay_state->crtc_x ||
> >>>>>>           primary_state->crtc_y < overlay_state->crtc_y ||
> >>>>>>
> >>>>>
> >>
> >> --
> >> Rodrigo Siqueira
> >> https://siqueira.tech/>
>

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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Michel Dänzer]

On 2021-06-07 8:45 p.m., Sean Paul wrote:
> 
> 
> On Mon, Jun 7, 2021 at 2:37 PM Harry Wentland <harry.wentland@amd.com <mailto:harry.wentland@amd.com>> wrote:
> 
>     On 2021-06-07 2:19 p.m., Sean Paul wrote:
>     > On Tue, May 18, 2021 at 2:58 PM Rodrigo Siqueira
>     > <Rodrigo.Siqueira@amd.com <mailto:Rodrigo.Siqueira@amd.com>> wrote:
>     >>
>     >> On 05/14, Mark Yacoub wrote:
>     >>> On Fri, May 14, 2021 at 12:31 PM Mark Yacoub <markyacoub@google.com <mailto:markyacoub@google.com>> wrote:
>     >>>>
>     >>>> On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland@amd.com <mailto:harry.wentland@amd.com>> wrote:
>     >>>>>
>     >>>>> On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
>     >>>>>> A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
>     >>>>>> fixed it in the commit:
>     >>>>>>
>     >>>>>>  drm/amd/display: Fix two cursor duplication when using overlay
>     >>>>>>  (read the commit message for more details)
>     >>>>>>
>     >>>>>> After this change, we noticed that some IGT subtests related to
>     >>>>>> kms_plane and kms_plane_scaling started to fail. After investigating
>     >>>>>> this issue, we noticed that all subtests that fail have a primary plane
>     >>>>>> covering the overlay plane, which is currently rejected by amdgpu dm.
>     >>>>>> Fail those IGT tests highlight that our verification was too broad and
>     >>>>>> compromises the overlay usage in our drive. This patch fixes this issue
>     >>> nit: s/drive/driver?
>     >>>>>> by ensuring that we only reject commits where the primary plane is not
>     >>>>>> fully covered by the overlay when the cursor hardware is enabled. With
>     >>>>>> this fix, all IGT tests start to pass again, which means our overlay
>     >>>>>> support works as expected.
>     >>>>>>
>     >>>>>> Cc: Tianci.Yin <tianci.yin@amd.com <mailto:tianci.yin@amd.com>>
>     >>>>>> Cc: Harry Wentland <harry.wentland@amd.com <mailto:harry.wentland@amd.com>>
>     >>>>>> Cc: Nicholas Choi <nicholas.choi@amd.com <mailto:nicholas.choi@amd.com>>
>     >>>>>> Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com <mailto:bhawanpreet.lakha@amd.com>>
>     >>>>>> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com <mailto:Nicholas.Kazlauskas@amd.com>>
>     >>>>>> Cc: Mark Yacoub <markyacoub@google.com <mailto:markyacoub@google.com>>
>     >>>>>> Cc: Daniel Wheeler <daniel.wheeler@amd.com <mailto:daniel.wheeler@amd.com>>
>     >>>>>>
>     >>>>>> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com <mailto:Rodrigo.Siqueira@amd.com>>
>     >>>>>> ---
>     >>>>>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
>     >>>>>>  1 file changed, 9 insertions(+), 1 deletion(-)
>     >>>>>>
>     >>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>     >>>>>> index ccd67003b120..9c2537a17a7b 100644
>     >>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>     >>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>     >>>>>> @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
>     >>>>>>       int i;
>     >>>>>>       struct drm_plane *plane;
>     >>>>>>       struct drm_plane_state *old_plane_state, *new_plane_state;
>     >>>>>> -     struct drm_plane_state *primary_state, *overlay_state = NULL;
>     >>>>>> +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
>     >>>>>>
>     >>>>>>       /* Check if primary plane is contained inside overlay */
>     >>>>>>       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
>     >>>>>> @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
>     >>>>>>       if (!primary_state->crtc)
>     >>>>>>               return 0;
>     >>>>>>
>     >>>>>> +     /* check if cursor plane is enabled */
>     >>>>>> +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
>     >>>>>> +     if (IS_ERR(cursor_state))
>     >>>>>> +             return PTR_ERR(cursor_state);
>     >>>>>> +
>     >>>>>> +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
>     >>>>>> +             return 0;
>     >>>>>> +
>     >>>>>
>     >>>>> I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
>     >>>>> based solely on whether a cursor is enabled or not.
>     >>> For context: To use overlays (the old/current async way), Chrome tests
>     >>> if an overlay strategy will work by doing an atomic commit with a TEST
>     >>> flag to check if the combination would work. If it works, it flags
>     >>> this planes configuration as valid. As it's valid, it performs an
>     >>> atomic page flip (which could also include the cursor).
>     >>> So to Harry's point, you would pass an atomic test but fail on an
>     >>> atomic page flip with the exact same configuration that's been flagged
>     >>> as valid. Failing a pageflip causes Chrome to crash (Reset the GPU
>     >>> process cause something went horribly wrong when it shouldn't).
>     >>
>     >> Hi Mark and Sean,
>     >>
>     >> I don't know if I fully comprehended the scenario which in my patch
>     >> might cause a ChromeOS crash, but this is what I understood:
>     >>
>     >
>     > Chrome compositor only does an atomic test when the layout geometry
>     > changes (ie: plane is added/removed/resized/moved). This does not take
>     > into consideration the cursor. Once the atomic test has been validated
>     > for a given layout geometry (set of planes/fbs along with their sizes
>     > and locations), Chrome assumes this will continue to be valid.
>     >
>     > So the situation I'm envisioning is if the cursor is hidden, an
>     > overlay-based strategy will pass in the kernel. If at any time the
>     > cursor becomes visible, the kernel will start failing commits which
>     > causes Chrome's GPU process to crash.
>     >
>     > In general I'm uneasy with using the cursor in the atomic check since
>     > it feels like it could be racy independent of the issue above. I
>     > haven't dove into the helper code enough to prove it, just a
>     > spidey-sense.
>     >
> 
>     Isn't the cursor supposed to be just another plane? If so, shouldn't
>     adding/removing the cursor trigger an atomic test?
> 
> 
> Chrome is using legacy cursor.
> 
> Yes it will trigger an atomic test in the kernel, and that atomic test will fail. Unfortunately Chrome does not expect a failure so it will crash.

The solution is probably indeed for atomic check to reject state which couldn't work if the cursor was enabled, even if the cursor is currently disabled. Otherwise one can hit various surprising errors via legacy APIs, as described in b836a274b797 "drm/amdgpu/dc: Require primary plane to be enabled whenever the CRTC is".


-- 
Earthling Michel Dänzer               |               https://redhat.com
Libre software enthusiast             |             Mesa and X developer
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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Harry Wentland]

On 2021-06-08 3:47 a.m., Michel Dänzer wrote:
> On 2021-06-07 8:45 p.m., Sean Paul wrote:
>>
>>
>> On Mon, Jun 7, 2021 at 2:37 PM Harry Wentland <harry.wentland@amd.com <mailto:harry.wentland@amd.com>> wrote:
>>
>>     On 2021-06-07 2:19 p.m., Sean Paul wrote:
>>     > On Tue, May 18, 2021 at 2:58 PM Rodrigo Siqueira
>>     > <Rodrigo.Siqueira@amd.com <mailto:Rodrigo.Siqueira@amd.com>> wrote:
>>     >>

<snip>

>>     >> Hi Mark and Sean,
>>     >>
>>     >> I don't know if I fully comprehended the scenario which in my patch
>>     >> might cause a ChromeOS crash, but this is what I understood:
>>     >>
>>     >
>>     > Chrome compositor only does an atomic test when the layout geometry
>>     > changes (ie: plane is added/removed/resized/moved). This does not take
>>     > into consideration the cursor. Once the atomic test has been validated
>>     > for a given layout geometry (set of planes/fbs along with their sizes
>>     > and locations), Chrome assumes this will continue to be valid.
>>     >
>>     > So the situation I'm envisioning is if the cursor is hidden, an
>>     > overlay-based strategy will pass in the kernel. If at any time the
>>     > cursor becomes visible, the kernel will start failing commits which
>>     > causes Chrome's GPU process to crash.
>>     >
>>     > In general I'm uneasy with using the cursor in the atomic check since
>>     > it feels like it could be racy independent of the issue above. I
>>     > haven't dove into the helper code enough to prove it, just a
>>     > spidey-sense.
>>     >
>>
>>     Isn't the cursor supposed to be just another plane? If so, shouldn't
>>     adding/removing the cursor trigger an atomic test?
>>
>>
>> Chrome is using legacy cursor.
>>
>> Yes it will trigger an atomic test in the kernel, and that atomic test will fail. Unfortunately Chrome does not expect a failure so it will crash.
> 
> The solution is probably indeed for atomic check to reject state which couldn't work if the cursor was enabled, even if the cursor is currently disabled. Otherwise one can hit various surprising errors via legacy APIs, as described in b836a274b797 "drm/amdgpu/dc: Require primary plane to be enabled whenever the CRTC is".
> 

Agreed.

It's a bit unfortunate but the only way to deal with this better is if we had some way for DRM master to tell us whether it will only use the atomic IOCTL or use legacy IOCTLs (including a combination of atomic and legacy).

Harry

> 

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Re: [PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Sean Paul]

On Tue, Jun 8, 2021 at 3:07 PM Harry Wentland <harry.wentland@amd.com> wrote:
>
>
>
> On 2021-06-08 3:47 a.m., Michel Dänzer wrote:
> > On 2021-06-07 8:45 p.m., Sean Paul wrote:
> >>
> >>
> >> On Mon, Jun 7, 2021 at 2:37 PM Harry Wentland <harry.wentland@amd.com <mailto:harry.wentland@amd.com>> wrote:
> >>
> >>     On 2021-06-07 2:19 p.m., Sean Paul wrote:
> >>     > On Tue, May 18, 2021 at 2:58 PM Rodrigo Siqueira
> >>     > <Rodrigo.Siqueira@amd.com <mailto:Rodrigo.Siqueira@amd.com>> wrote:
> >>     >>
>
> <snip>
>
> >>     >> Hi Mark and Sean,
> >>     >>
> >>     >> I don't know if I fully comprehended the scenario which in my patch
> >>     >> might cause a ChromeOS crash, but this is what I understood:
> >>     >>
> >>     >
> >>     > Chrome compositor only does an atomic test when the layout geometry
> >>     > changes (ie: plane is added/removed/resized/moved). This does not take
> >>     > into consideration the cursor. Once the atomic test has been validated
> >>     > for a given layout geometry (set of planes/fbs along with their sizes
> >>     > and locations), Chrome assumes this will continue to be valid.
> >>     >
> >>     > So the situation I'm envisioning is if the cursor is hidden, an
> >>     > overlay-based strategy will pass in the kernel. If at any time the
> >>     > cursor becomes visible, the kernel will start failing commits which
> >>     > causes Chrome's GPU process to crash.
> >>     >
> >>     > In general I'm uneasy with using the cursor in the atomic check since
> >>     > it feels like it could be racy independent of the issue above. I
> >>     > haven't dove into the helper code enough to prove it, just a
> >>     > spidey-sense.
> >>     >
> >>
> >>     Isn't the cursor supposed to be just another plane? If so, shouldn't
> >>     adding/removing the cursor trigger an atomic test?
> >>
> >>
> >> Chrome is using legacy cursor.
> >>
> >> Yes it will trigger an atomic test in the kernel, and that atomic test will fail. Unfortunately Chrome does not expect a failure so it will crash.
> >
> > The solution is probably indeed for atomic check to reject state which couldn't work if the cursor was enabled, even if the cursor is currently disabled. Otherwise one can hit various surprising errors via legacy APIs, as described in b836a274b797 "drm/amdgpu/dc: Require primary plane to be enabled whenever the CRTC is".
> >
>
> Agreed.
>
> It's a bit unfortunate but the only way to deal with this better is if we had some way for DRM master to tell us whether it will only use the atomic IOCTL or use legacy IOCTLs (including a combination of atomic and legacy).
>

I think even with this information we wouldn't want to depend on
cursor for atomic test. IMO kernel should not back the compositor into
re-rendering the scene based on cursor visibility. Given that cursor
is usually handled independently and asynchronously from composition,
it makes things extremely complex and most compositors would probably
just enable cursor all the time to work around this.

Sean


> Harry
>
> >
>
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