xf86-video-intel: src/sna/sna_render.c

[Chris Wilson]

 src/sna/sna_render.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

New commits:
commit bca4e0e35e4ac27f2dcd1a8e5fcbf7ce69cec358
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Sat Apr 23 21:42:12 2016 +0100

    sna: Limit generic convolution to smallish kernels
    
    Since the naive implementation uses an 8bit temporary, we can only
    support so many passes before the quantization artefacts become
    apparent. We have to be extra conservation in order to support
    multi-pass convolution algorithms (notable 2-pass separable Gaussian
    kernels).
    
    References: https://bugs.freedesktop.org/show_bug.cgi?id=95091
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

diff --git a/src/sna/sna_render.c b/src/sna/sna_render.c
index d8b7756..5a8df06 100644
--- a/src/sna/sna_render.c
+++ b/src/sna/sna_render.c
@@ -1326,6 +1326,8 @@ sna_render_picture_convolve(struct sna *sna,
 	 */
 	DBG(("%s: origin=(%d,%d) kernel=%dx%d, size=%dx%d\n",
 	     __FUNCTION__, x_off, y_off, cw, ch, w, h));
+	if (cw*ch > 32) /* too much loss of precision from quantization! */
+		return -1;
 
 	assert(picture->pDrawable);
 	assert(picture->filter == PictFilterConvolution);
@@ -1376,9 +1378,9 @@ sna_render_picture_convolve(struct sna *sna,
 			alpha = CreateSolidPicture(0, &color, &error);
 			if (alpha) {
 				sna_composite(PictOpAdd, picture, alpha, tmp,
-					      x, y,
+					      x-(x_off+i), y-(y_off+j),
+					      0, 0,
 					      0, 0,
-					      x_off+i, y_off+j,
 					      w, h);
 				FreePicture(alpha, 0);
 			}