Re: [Intel-gfx] [PATCH v2 03/10] drm/i915: move checks of intel_crtc_cursor_set_obj() out

[Gustavo Padovan <gustavo.padovan@collabora.co.uk>]

2014-09-23 Ville Syrjälä <ville.syrjala@linux.intel.com>:

> On Mon, Sep 22, 2014 at 07:23:10PM -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > 
> > Move checks inside intel_crtc_cursor_set_obj() to
> > intel_check_cursor_plane(), we only use they there so move them out to
> > make the merge of intel_crtc_cursor_set_obj() into
> > intel_check_cursor_plane() easier.
> > 
> > This is another step toward the atomic modesetting support and unification
> > of plane operations such pin/unpin of fb objects on i915.
> > 
> > v2: take Ville's comment: move crtc_{w,h} assignment a bit down in the
> > code
> > 
> > Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 61 ++++++++++++++++++++++++------------
> >  1 file changed, 41 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 2ef1836..3f37e93 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -8373,7 +8373,7 @@ static int intel_crtc_cursor_set_obj(struct drm_crtc *crtc,
> >  	struct drm_i915_private *dev_priv = dev->dev_private;
> >  	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> >  	enum pipe pipe = intel_crtc->pipe;
> > -	unsigned old_width, stride;
> > +	unsigned old_width;
> >  	uint32_t addr;
> >  	int ret;
> >  
> > @@ -8385,29 +8385,11 @@ static int intel_crtc_cursor_set_obj(struct drm_crtc *crtc,
> >  		goto finish;
> >  	}
> >  
> > -	/* Check for which cursor types we support */
> > -	if (!cursor_size_ok(dev, width, height)) {
> > -		DRM_DEBUG("Cursor dimension not supported\n");
> > -		return -EINVAL;
> > -	}
> > -
> > -	stride = roundup_pow_of_two(width) * 4;
> > -	if (obj->base.size < stride * height) {
> > -		DRM_DEBUG_KMS("buffer is too small\n");
> > -		return -ENOMEM;
> > -	}
> > -
> >  	/* we only need to pin inside GTT if cursor is non-phy */
> >  	mutex_lock(&dev->struct_mutex);
> >  	if (!INTEL_INFO(dev)->cursor_needs_physical) {
> >  		unsigned alignment;
> >  
> > -		if (obj->tiling_mode) {
> > -			DRM_DEBUG_KMS("cursor cannot be tiled\n");
> > -			ret = -EINVAL;
> > -			goto fail_locked;
> > -		}
> > -
> >  		/*
> >  		 * Global gtt pte registers are special registers which actually
> >  		 * forward writes to a chunk of system memory. Which means that
> > @@ -11826,16 +11808,55 @@ intel_check_cursor_plane(struct drm_plane *plane,
> >  			 struct intel_plane_state *state)
> >  {
> >  	struct drm_crtc *crtc = state->crtc;
> > +	struct drm_device *dev = crtc->dev;
> >  	struct drm_framebuffer *fb = state->fb;
> >  	struct drm_rect *dest = &state->dst;
> >  	struct drm_rect *src = &state->src;
> >  	const struct drm_rect *clip = &state->clip;
> > +	struct drm_i915_gem_object *obj = intel_fb_obj(fb);
> > +	int crtc_w, crtc_h;
> > +	unsigned stride;
> > +	int ret;
> >  
> > -	return drm_plane_helper_check_update(plane, crtc, fb,
> > +	ret = drm_plane_helper_check_update(plane, crtc, fb,
> >  					    src, dest, clip,
> >  					    DRM_PLANE_HELPER_NO_SCALING,
> >  					    DRM_PLANE_HELPER_NO_SCALING,
> >  					    true, true, &state->visible);
> > +	if (ret)
> > +		return ret;
> > +
> > +
> > +	/* if we want to turn off the cursor ignore width and height */
> > +	if (!obj)
> > +		return 0;
> > +
> > +	if (fb == crtc->cursor->fb)
> > +		return 0;
> 
> Hmm. This check needs to be after the cursor/obj size checks. Otherwise
> we wouldn't reject invalid sized cursors when the fb didn't change. I
> suppose we could also just drop this check, but it can still save us from
> doing the tiling check since that can't have changed if the fb hasn't
> changed so maybe it's worth keeping. But either solution is fine by me.

Only if this was a bug before this patch, if you look at the original
intel_commit_cursor_plane() we do two things when the fbs are the same:
               
	intel_crtc_update_cursor();
	intel_frontbuffer_flip();

No checks are performed, that is why I put the fbs check before any other
check to make the code as similar as possible to what it was before.

> > +
> > +	/* Check for which cursor types we support */
> > +	crtc_w = drm_rect_width(&state->orig_dst);
> > +	crtc_h = drm_rect_height(&state->orig_dst);
> > +	if (!cursor_size_ok(dev, crtc_w, crtc_h)) {
> > +		DRM_DEBUG("Cursor dimension not supported\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	stride = roundup_pow_of_two(crtc_w) * 4;
> > +	if (obj->base.size < stride * crtc_h) {
> > +		DRM_DEBUG_KMS("buffer is too small\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	/* we only need to pin inside GTT if cursor is non-phy */
> > +	mutex_lock(&dev->struct_mutex);
> > +	if (!INTEL_INFO(dev)->cursor_needs_physical && obj->tiling_mode) {
> > +		DRM_DEBUG_KMS("cursor cannot be tiled\n");
> > +		ret = -EINVAL;
> > +	}
> > +	mutex_unlock(&dev->struct_mutex);
> > +
> > +	return ret;
> 
> 'return 0' seems better here.

ret can be -EINVAL, the code inside the mutex 3 lines above can set ret.

	Gustavo