Re: [PATCH] drm/i915: Detect invalid scanout pitches

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jun 20, 2013 at 05:14:20PM +0100, Chris Wilson wrote:
> Report back the user error of attempting to setup a CRTC with an invalid
> framebuffer pitch. This is trickier than it should be as on gen4, there
> is a restriction that tiled surfaces must have a stride less than 16k -
> which is less than the largest supported CRTC size.
> 
> v2: Fix the limits for gen3
> v3: Move check into intel_framebuffer_init() and fix VLV limits. (vsyrjala)
> 
> References: https://bugs.freedesktop.org/show_bug.cgi?id=65099
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 03a5ed0..ed84c57 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9223,6 +9223,7 @@ int intel_framebuffer_init(struct drm_device *dev,
>  			   struct drm_mode_fb_cmd2 *mode_cmd,
>  			   struct drm_i915_gem_object *obj)
>  {
> +	int pitch_limit;
>  	int ret;
>  
>  	if (obj->tiling_mode == I915_TILING_Y) {
> @@ -9236,10 +9237,26 @@ int intel_framebuffer_init(struct drm_device *dev,
>  		return -EINVAL;
>  	}
>  
> -	/* FIXME <= Gen4 stride limits are bit unclear */
> -	if (mode_cmd->pitches[0] > 32768) {
> -		DRM_DEBUG("pitch (%d) must be at less than 32768\n",
> -			  mode_cmd->pitches[0]);
> +	if (INTEL_INFO(dev)->gen > 4 && !IS_VALLEYVIEW(dev)) {

I believe Daniel wants to use >= for such gen checks, and I tend to
agree that it would make things a bit easier to parse.

> +		pitch_limit = 32*1024;
> +	} else if (INTEL_INFO(dev)->gen > 3) {
> +		if (obj->tiling_mode)
> +			pitch_limit = 16*1024;
> +		else
> +			pitch_limit = 32*1024;
> +	} else if (INTEL_INFO(dev)->gen > 2) {
> +		if (obj->tiling_mode)
> +			pitch_limit = 8*1024;
> +		else
> +			pitch_limit = 16*1024;
> +	} else
> +		/* XXX DSPC is limited to 4k tiled */
> +		pitch_limit = 8*1024;
> +
> +	if (mode_cmd->pitches[0] > pitch_limit) {
> +		DRM_DEBUG("%s pitch (%d) must be at less than %d\n",
> +			  obj->tiling_mode ? "tiled" : "linear",
> +			  mode_cmd->pitches[0], pitch_limit);
>  		return -EINVAL;
>  	}
>  
> -- 
> 1.8.3.1
> 
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-- 
Ville Syrjälä
Intel OTC