Re: [Intel-gfx] [PATCH 4/4] drm/vc4: Validate framebuffer pixel format/modifier

[Daniel Vetter]

On Fri, Mar 09, 2018 at 12:54:43PM -0800, Eric Anholt wrote:
> Ville Syrjala  writes:
> 
> > From: Ville Syrj??l?? 
> >
> > Only create framebuffers with supported format/modifier combinations by
> > checking that at least one plane supports the requested combination.
> >
> > Using drm_any_plane_has_format() is somewhat suboptimal for vc4 since
> > the planes have (mostly) uniform capabilities. But I was lazy and
> > didn't feel like exporting drm_plane_format_check() and hand rolling
> > anything better. Also I really just wanted to come up with another
> > user for drm_any_plane_has_format() ;)
> 
> I'm not excited about vc4 having error-return behavior that other
> drivers don't have.  Actually, I don't really see why we should be doing
> this check in fb create at all, given that you have to do so again at
> atomic_check time with the specific plane.
> 
> Could you just delete the i915 fb format check code?

Yeah I thought we agreed that any driver not using the compat primary
plane helper will get this checking by default? That seems simplest, and
safest too.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH 4/4] drm/vc4: Validate framebuffer pixel format/modifier

[Ville Syrjälä]

On Fri, Mar 09, 2018 at 12:54:43PM -0800, Eric Anholt wrote:
> Ville Syrjala  writes:
> 
> > From: Ville Syrjälä 
> >
> > Only create framebuffers with supported format/modifier combinations by
> > checking that at least one plane supports the requested combination.
> >
> > Using drm_any_plane_has_format() is somewhat suboptimal for vc4 since
> > the planes have (mostly) uniform capabilities. But I was lazy and
> > didn't feel like exporting drm_plane_format_check() and hand rolling
> > anything better. Also I really just wanted to come up with another
> > user for drm_any_plane_has_format() ;)
> 
> I'm not excited about vc4 having error-return behavior that other
> drivers don't have.  Actually, I don't really see why we should be doing
> this check in fb create at all, given that you have to do so again at
> atomic_check time with the specific plane.
> 
> Could you just delete the i915 fb format check code?

I don't want unsupported formats to get anywhere near the driver
code. Makes life much less stressful when you know what can and
can't get in.

Also I see no good reason to allow userspace to create fbs it
can't actually use later on. Much better to reject early and tell
userspace to pick another format. I imagine pre-blobifier userspace
could even use this as a way to probe what's supported by the driver.

-- 
Ville Syrjälä
Intel OTC
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Re: [Intel-gfx] [PATCH 4/4] drm/vc4: Validate framebuffer pixel format/modifier

[Eric Anholt]

Ville Syrjala  writes:

> From: Ville Syrjälä 
>
> Only create framebuffers with supported format/modifier combinations by
> checking that at least one plane supports the requested combination.
>
> Using drm_any_plane_has_format() is somewhat suboptimal for vc4 since
> the planes have (mostly) uniform capabilities. But I was lazy and
> didn't feel like exporting drm_plane_format_check() and hand rolling
> anything better. Also I really just wanted to come up with another
> user for drm_any_plane_has_format() ;)

I'm not excited about vc4 having error-return behavior that other
drivers don't have.  Actually, I don't really see why we should be doing
this check in fb create at all, given that you have to do so again at
atomic_check time with the specific plane.

Could you just delete the i915 fb format check code?


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[Intel-gfx] [PATCH 4/4] drm/vc4: Validate framebuffer pixel format/modifier

[Ville Syrjala]

From: Ville Syrjälä 

Only create framebuffers with supported format/modifier combinations by
checking that at least one plane supports the requested combination.

Using drm_any_plane_has_format() is somewhat suboptimal for vc4 since
the planes have (mostly) uniform capabilities. But I was lazy and
didn't feel like exporting drm_plane_format_check() and hand rolling
anything better. Also I really just wanted to come up with another
user for drm_any_plane_has_format() ;)

Compile tested only.

Cc: Eric Anholt 
Signed-off-by: Ville Syrjälä 
---
 drivers/gpu/drm/vc4/vc4_kms.c | 11 +++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index ba60153dddb5..b6f15102dda0 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -184,6 +184,17 @@ static struct drm_framebuffer *vc4_fb_create(struct 
drm_device *dev,
mode_cmd = _cmd_local;
}
 
+   if (!drm_any_plane_has_format(dev, mode_cmd->pixel_format,
+ mode_cmd->modifier[0])) {
+   struct drm_format_name_buf format_name;
+
+   DRM_DEBUG_KMS("unsupported pixel format %s / modifier 0x%llx\n",
+ drm_get_format_name(mode_cmd->pixel_format,
+ _name),
+ mode_cmd->modifier[0]);
+   return ERR_PTR(-EINVAL);
+   }
+
return drm_gem_fb_create(dev, file_priv, mode_cmd);
 }
 
-- 
2.16.1

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