From 8d65ef5957aee3998a1476d2436ae26168b99120 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Fri, 22 Nov 2019 19:56:22 +0200
Subject: drm/rect: Keep the clipped dst rectangle in place
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Git-commit: 2020af2dbf734a16886d5e9e1f65841641db5f33
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Now that we've constrained the clipped source rectangle such
that it can't have negative dimensions doing the same for the
dst rectangle seems appropriate. Should at least result in
the clipped src and dst rectangles being a bit more consistent
with each other.

Cc: Benjamin Gaignard <benjamin.gaignard@st.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191122175623.13565-4-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/drm_rect.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
index a9c7f90836f3..1e1e2101007a 100644
--- a/drivers/gpu/drm/drm_rect.c
+++ b/drivers/gpu/drm/drm_rect.c
@@ -52,7 +52,7 @@ bool drm_rect_intersect(struct drm_rect *r1, const struct drm_rect *r2)
 }
 EXPORT_SYMBOL(drm_rect_intersect);
 
-static u32 clip_scaled(u32 src, u32 dst, u32 clip)
+static u32 clip_scaled(int src, int dst, int *clip)
 {
 	u64 tmp;
 
@@ -60,9 +60,9 @@ static u32 clip_scaled(u32 src, u32 dst, u32 clip)
 		return 0;
 
 	/* Only clip what we have. Keeps the result bounded. */
-	clip = min(clip, dst);
+	*clip = min(*clip, dst);
 
-	tmp = mul_u32_u32(src, dst - clip);
+	tmp = mul_u32_u32(src, dst - *clip);
 
 	/*
 	 * Round toward 1.0 when clipping so that we don't accidentally
@@ -95,34 +95,34 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,
 	diff = clip->x1 - dst->x1;
 	if (diff > 0) {
 		u32 new_src_w = clip_scaled(drm_rect_width(src),
-					    drm_rect_width(dst), diff);
+					    drm_rect_width(dst), &diff);
 
 		src->x1 = src->x2 - new_src_w;
-		dst->x1 = clip->x1;
+		dst->x1 += diff;
 	}
 	diff = clip->y1 - dst->y1;
 	if (diff > 0) {
 		u32 new_src_h = clip_scaled(drm_rect_height(src),
-					    drm_rect_height(dst), diff);
+					    drm_rect_height(dst), &diff);
 
 		src->y1 = src->y2 - new_src_h;
-		dst->y1 = clip->y1;
+		dst->y1 += diff;
 	}
 	diff = dst->x2 - clip->x2;
 	if (diff > 0) {
 		u32 new_src_w = clip_scaled(drm_rect_width(src),
-					    drm_rect_width(dst), diff);
+					    drm_rect_width(dst), &diff);
 
 		src->x2 = src->x1 + new_src_w;
-		dst->x2 = clip->x2;
+		dst->x2 -= diff;
 	}
 	diff = dst->y2 - clip->y2;
 	if (diff > 0) {
 		u32 new_src_h = clip_scaled(drm_rect_height(src),
-					    drm_rect_height(dst), diff);
+					    drm_rect_height(dst), &diff);
 
 		src->y2 = src->y1 + new_src_h;
-		dst->y2 = clip->y2;
+		dst->y2 -= diff;
 	}
 
 	return drm_rect_visible(dst);
-- 
2.28.0