drm/rect: Round above 1 << 16 upwards to correct scale calculation functions.

[sfrench/cifs-2.6.git] / drivers / gpu / drm / drm_rect.c

diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
index 9817c1445ba9ea8f97a1c0fbcfd75851d7f271fd..a8e934795c7d7c746ab977307907c849a5605283 100644 (file)
--- a/drivers/gpu/drm/drm_rect.c
+++ b/drivers/gpu/drm/drm_rect.c
@@ -106,7 +106,10 @@ static int drm_calc_scale(int src, int dst)
        if (dst == 0)
                return 0;
 
-       scale = src / dst;
+       if (src > (dst << 16))
+               return DIV_ROUND_UP(src, dst);
+       else
+               scale = src / dst;
 
        return scale;
 }
@@ -121,6 +124,10 @@ static int drm_calc_scale(int src, int dst)
  * Calculate the horizontal scaling factor as
  * (@src width) / (@dst width).
  *
+ * If the scale is below 1 << 16, round down. If the scale is above
+ * 1 << 16, round up. This will calculate the scale with the most
+ * pessimistic limit calculation.
+ *
  * RETURNS:
  * The horizontal scaling factor, or errno of out of limits.
  */
@@ -152,6 +159,10 @@ EXPORT_SYMBOL(drm_rect_calc_hscale);
  * Calculate the vertical scaling factor as
  * (@src height) / (@dst height).
  *
+ * If the scale is below 1 << 16, round down. If the scale is above
+ * 1 << 16, round up. This will calculate the scale with the most
+ * pessimistic limit calculation.
+ *
  * RETURNS:
  * The vertical scaling factor, or errno of out of limits.
  */
@@ -189,6 +200,10 @@ EXPORT_SYMBOL(drm_rect_calc_vscale);
  * If the calculated scaling factor is above @max_vscale,
  * decrease the height of rectangle @src to compensate.
  *
+ * If the scale is below 1 << 16, round down. If the scale is above
+ * 1 << 16, round up. This will calculate the scale with the most
+ * pessimistic limit calculation.
+ *
  * RETURNS:
  * The horizontal scaling factor.
  */
@@ -239,6 +254,10 @@ EXPORT_SYMBOL(drm_rect_calc_hscale_relaxed);
  * If the calculated scaling factor is above @max_vscale,
  * decrease the height of rectangle @src to compensate.
  *
+ * If the scale is below 1 << 16, round down. If the scale is above
+ * 1 << 16, round up. This will calculate the scale with the most
+ * pessimistic limit calculation.
+ *
  * RETURNS:
  * The vertical scaling factor.
  */
@@ -373,8 +392,8 @@ EXPORT_SYMBOL(drm_rect_rotate);
  * them when doing a rotatation and its inverse.
  * That is, if you do ::
  *
- *     DRM_MODE_PROP_ROTATE(&r, width, height, rotation);
- *     DRM_MODE_ROTATE_inv(&r, width, height, rotation);
+ *     drm_rect_rotate(&r, width, height, rotation);
+ *     drm_rect_rotate_inv(&r, width, height, rotation);
  *
  * you will always get back the original rectangle.
  */