On Wed, Nov 20, 2019 at 05:22:34PM +0200, Ville Syrjälä wrote:

On Tue, Nov 19, 2019 at 02:34:35PM +0100, Benjamin Gaignard wrote:

...

Clamping a value between INT_MIN and INT_MAX always return the value itself and generate warnings when compiling with W=1.

Signed-off-by: Benjamin Gaignard benjamin.gaignard@st.com

drivers/gpu/drm/drm_rect.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c index b8363aaa9032..681f1fd09357 100644 --- a/drivers/gpu/drm/drm_rect.c +++ b/drivers/gpu/drm/drm_rect.c @@ -89,7 +89,7 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst, u32 new_src_w = clip_scaled(drm_rect_width(src), drm_rect_width(dst), diff);

Hmm. I think we borked this a bit when introducing clip_scaled(). 'diff' can exceed dst width here so clip_scaled() should be able to return a negative value.

Probably we should make this more consistent and do something like: diff = clip->x1 - dst->x1; if (diff > 0) {

•           u32 new_src_w = clip_scaled(drm_rect_width(src),
  

•                                       drm_rect_width(dst), diff);
  

•           int dst_w, new_src_w;
  
  

•           src->x1 = clamp_t(int64_t, src->x2 - new_src_w, INT_MIN, INT_MAX);
  

•           dst->x1 = clip->x1;
  

•           dst_w = drm_rect_width(dst);
  

•           diff = min(diff, dst_w);
  

•           new_src_w = clip_scaled(drm_rect_width(src), dst_w, diff);
  

•           src->x1 = src->x2 - new_src_w;
  

•           dst->x1 += diff;
    }
  
  

etc.

I tried to refine that a bit more and sent it out as two patches.

...

• src->x1 = clamp_t(int64_t, src->x2 - new_src_w, INT_MIN, INT_MAX);
  

• src->x1 = src->x2 - new_src_w;
  

  dst->x1 = clip->x1; } diff = clip->y1 - dst->y1;

@@ -97,7 +97,7 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst, u32 new_src_h = clip_scaled(drm_rect_height(src), drm_rect_height(dst), diff);

• src->y1 = clamp_t(int64_t, src->y2 - new_src_h, INT_MIN, INT_MAX);
  

• src->y1 = src->y2 - new_src_h;
  

  dst->y1 = clip->y1; } diff = dst->x2 - clip->x2;

@@ -105,7 +105,7 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst, u32 new_src_w = clip_scaled(drm_rect_width(src), drm_rect_width(dst), diff);

• src->x2 = clamp_t(int64_t, src->x1 + new_src_w, INT_MIN, INT_MAX);
  

• src->x2 = src->x1 + new_src_w;
  

  dst->x2 = clip->x2; } diff = dst->y2 - clip->y2;

@@ -113,7 +113,7 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst, u32 new_src_h = clip_scaled(drm_rect_height(src), drm_rect_height(dst), diff);

• src->y2 = clamp_t(int64_t, src->y1 + new_src_h, INT_MIN, INT_MAX);
  

• src->y2 = src->y1 + new_src_h;
  

  dst->y2 = clip->y2; }

-- 2.15.0

---

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-- Ville Syrjälä Intel