Re: [Intel-gfx] [PATCH 1/3] drm: Check CRTC compatibility in setplane

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Apr 23, 2014 at 10:03:59AM -0700, Matt Roper wrote:
> The DRM core setplane code should check that the plane is usable on the
> specified CRTC before calling into the driver.
> 
> Prior to this patch, a plane's possible_crtcs field was purely
> informational for userspace and was never actually verified at the
> kernel level (aside from the primary plane helper).
> 
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>

Do you have a nasty igt somewhere which tries to use a plane on the wrong
crtc? Especially useful since our i915 code and hw relies on this.
-Daniel

> ---
>  drivers/gpu/drm/drm_crtc.c         | 7 +++++++
>  drivers/gpu/drm/drm_plane_helper.c | 6 ------
>  2 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 461d19b..b6d6c04 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -2140,6 +2140,13 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
>  	}
>  	crtc = obj_to_crtc(obj);
>  
> +	/* Check whether this plane is usable on this CRTC */
> +	if (!(plane->possible_crtcs & drm_crtc_mask(crtc))) {
> +		DRM_DEBUG_KMS("Invalid crtc for plane\n");
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	fb = drm_framebuffer_lookup(dev, plane_req->fb_id);
>  	if (!fb) {
>  		DRM_DEBUG_KMS("Unknown framebuffer ID %d\n",
> diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
> index b72736d..65c4a00 100644
> --- a/drivers/gpu/drm/drm_plane_helper.c
> +++ b/drivers/gpu/drm/drm_plane_helper.c
> @@ -137,12 +137,6 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc,
>  		return -EINVAL;
>  	}
>  
> -	/* Primary planes are locked to their owning CRTC */
> -	if (plane->possible_crtcs != drm_crtc_mask(crtc)) {
> -		DRM_DEBUG_KMS("Cannot change primary plane CRTC\n");
> -		return -EINVAL;
> -	}
> -
>  	/* Disallow scaling */
>  	src_w >>= 16;
>  	src_h >>= 16;
> -- 
> 1.8.5.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch