[PATCH 1/3] drm/rect: Round above 1 << 16 upwards to correct scale calculation functions.

[PATCH 1/3] drm/rect: Round above 1 << 16 upwards to correct scale calculation functions.

[Maarten Lankhorst]

When calculating limits we want to be as pessimistic as possible,
so we have to explicitly say whether we want to round up or down
to accurately calculate whether we are below min_scale or above
max_scale.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
 drivers/gpu/drm/drm_rect.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
index 9817c1445ba9..b179c7c73cc5 100644
--- 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 +124,9 @@ 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 above 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 +158,9 @@ 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 above 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 +198,9 @@ 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 above up. This will
+ * calculate the scale with the most pessimistic limit calculation.
+ *
  * RETURNS:
  * The horizontal scaling factor.
  */
@@ -239,6 +251,9 @@ 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 above up. This will
+ * calculate the scale with the most pessimistic limit calculation.
+ *
  * RETURNS:
  * The vertical scaling factor.
  */
-- 
2.17.0

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[PATCH 2/3] drm/rect: Handle rounding errors in drm_rect_clip_scaled

[Maarten Lankhorst]

No matter how you perform the clip adjustments, a small
error may push the scaling factor to the other side of
0x10000. Solve this with a macro that will fixup the
scale to 0x10000 if we accidentally wrap to the other side.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
 drivers/gpu/drm/drm_rect.c | 65 +++++++++++++++++++++++++++-----------
 1 file changed, 47 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
index b179c7c73cc5..71b6b7f5d58f 100644
--- a/drivers/gpu/drm/drm_rect.c
+++ b/drivers/gpu/drm/drm_rect.c
@@ -50,6 +50,24 @@ bool drm_rect_intersect(struct drm_rect *r1, const struct drm_rect *r2)
 }
 EXPORT_SYMBOL(drm_rect_intersect);
 
+static int drm_calc_scale(int src, int dst)
+{
+	int scale = 0;
+
+	if (WARN_ON(src < 0 || dst < 0))
+		return -EINVAL;
+
+	if (dst == 0)
+		return 0;
+
+	if (src > (dst << 16))
+		return DIV_ROUND_UP(src, dst);
+	else
+		scale = src / dst;
+
+	return scale;
+}
+
 /**
  * drm_rect_clip_scaled - perform a scaled clip operation
  * @src: source window rectangle
@@ -71,49 +89,60 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,
 {
 	int diff;
 
+	/*
+	 * When scale is near 0x10000 rounding errors may cause the scaling
+	 * factor to the other side. Some hardware may support
+	 * upsampling, but not downsampling, and that would break when
+	 * rounding.
+	 */
+#define FIXUP(oldscale, fn, m, second) do { \
+	if (oldscale != 1 << 16) { \
+		int newscale = drm_calc_scale(fn(src), fn(dst)); \
+ \
+		if (newscale < 0) \
+			return false; \
+ \
+		if ((oldscale < 0x10000) != (newscale < 0x10000)) { \
+			if (!second) \
+				src->m##1 = src->m##2 - ((fn(dst) - diff) << 16); \
+			else \
+				src->m##2 = src->m##1 + ((fn(dst) - diff) << 16); \
+		} \
+	} \
+ } while (0)
+
 	diff = clip->x1 - dst->x1;
 	if (diff > 0) {
 		int64_t tmp = src->x1 + (int64_t) diff * hscale;
 		src->x1 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
+		FIXUP(hscale, drm_rect_width, x, 0);
 	}
+
 	diff = clip->y1 - dst->y1;
 	if (diff > 0) {
 		int64_t tmp = src->y1 + (int64_t) diff * vscale;
 		src->y1 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
+		FIXUP(vscale, drm_rect_height, y, 0);
 	}
+
 	diff = dst->x2 - clip->x2;
 	if (diff > 0) {
 		int64_t tmp = src->x2 - (int64_t) diff * hscale;
 		src->x2 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
+		FIXUP(hscale, drm_rect_width, x, 1);
 	}
 	diff = dst->y2 - clip->y2;
 	if (diff > 0) {
 		int64_t tmp = src->y2 - (int64_t) diff * vscale;
 		src->y2 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
+		FIXUP(vscale, drm_rect_height, y, 1);
 	}
+#undef FIXUP
 
 	return drm_rect_intersect(dst, clip);
 }
 EXPORT_SYMBOL(drm_rect_clip_scaled);
 
-static int drm_calc_scale(int src, int dst)
-{
-	int scale = 0;
-
-	if (WARN_ON(src < 0 || dst < 0))
-		return -EINVAL;
-
-	if (dst == 0)
-		return 0;
-
-	if (src > (dst << 16))
-		return DIV_ROUND_UP(src, dst);
-	else
-		scale = src / dst;
-
-	return scale;
-}
-
 /**
  * drm_rect_calc_hscale - calculate the horizontal scaling factor
  * @src: source window rectangle
-- 
2.17.0

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[PATCH 3/3] drm/i915: Do not adjust scale when out of bounds, v2.

[Maarten Lankhorst]

With the previous patch drm_atomic_helper_check_plane_state correctly
calculates clipping and the xf86-video-intel ddx is fixed to fall back
to GPU correctly when SetPlane fails, we can remove the hack where
we try to pan/zoom when out of min/max scaling range. This was already
poor behavior where the screen didn't show what was requested, and now
instead we reject it outright. This simplifies check_sprite_plane a lot.

Changes since v1:
- Set crtc_h to the height correctly.
- Reject < 3x3 rectangles instead of making them invisible for <gen9.
  For gen9+ skl_update_scaler_plane will reject them.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_sprite.c | 144 +++++++---------------------
 1 file changed, 35 insertions(+), 109 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index aa1dfaa692b9..970015dcc6f1 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -936,22 +936,12 @@ intel_check_sprite_plane(struct intel_plane *plane,
 	struct drm_i915_private *dev_priv = to_i915(plane->base.dev);
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
 	struct drm_framebuffer *fb = state->base.fb;
-	int crtc_x, crtc_y;
-	unsigned int crtc_w, crtc_h;
-	uint32_t src_x, src_y, src_w, src_h;
-	struct drm_rect *src = &state->base.src;
-	struct drm_rect *dst = &state->base.dst;
-	struct drm_rect clip = {};
 	int max_stride = INTEL_GEN(dev_priv) >= 9 ? 32768 : 16384;
-	int hscale, vscale;
 	int max_scale, min_scale;
 	bool can_scale;
 	int ret;
 	uint32_t pixel_format = 0;
 
-	*src = drm_plane_state_src(&state->base);
-	*dst = drm_plane_state_dest(&state->base);
-
 	if (!fb) {
 		state->base.visible = false;
 		return 0;
@@ -990,64 +980,19 @@ intel_check_sprite_plane(struct intel_plane *plane,
 		min_scale = plane->can_scale ? 1 : (1 << 16);
 	}
 
-	/*
-	 * FIXME the following code does a bunch of fuzzy adjustments to the
-	 * coordinates and sizes. We probably need some way to decide whether
-	 * more strict checking should be done instead.
-	 */
-	drm_rect_rotate(src, fb->width << 16, fb->height << 16,
-			state->base.rotation);
-
-	hscale = drm_rect_calc_hscale_relaxed(src, dst, min_scale, max_scale);
-	BUG_ON(hscale < 0);
-
-	vscale = drm_rect_calc_vscale_relaxed(src, dst, min_scale, max_scale);
-	BUG_ON(vscale < 0);
-
-	if (crtc_state->base.enable)
-		drm_mode_get_hv_timing(&crtc_state->base.mode,
-				       &clip.x2, &clip.y2);
-
-	state->base.visible = drm_rect_clip_scaled(src, dst, &clip, hscale, vscale);
-
-	crtc_x = dst->x1;
-	crtc_y = dst->y1;
-	crtc_w = drm_rect_width(dst);
-	crtc_h = drm_rect_height(dst);
+	ret = drm_atomic_helper_check_plane_state(&state->base,
+						  &crtc_state->base,
+						  min_scale, max_scale,
+						  true, true);
+	if (ret)
+		return ret;
 
 	if (state->base.visible) {
-		/* check again in case clipping clamped the results */
-		hscale = drm_rect_calc_hscale(src, dst, min_scale, max_scale);
-		if (hscale < 0) {
-			DRM_DEBUG_KMS("Horizontal scaling factor out of limits\n");
-			drm_rect_debug_print("src: ", src, true);
-			drm_rect_debug_print("dst: ", dst, false);
-
-			return hscale;
-		}
-
-		vscale = drm_rect_calc_vscale(src, dst, min_scale, max_scale);
-		if (vscale < 0) {
-			DRM_DEBUG_KMS("Vertical scaling factor out of limits\n");
-			drm_rect_debug_print("src: ", src, true);
-			drm_rect_debug_print("dst: ", dst, false);
-
-			return vscale;
-		}
-
-		/* Make the source viewport size an exact multiple of the scaling factors. */
-		drm_rect_adjust_size(src,
-				     drm_rect_width(dst) * hscale - drm_rect_width(src),
-				     drm_rect_height(dst) * vscale - drm_rect_height(src));
-
-		drm_rect_rotate_inv(src, fb->width << 16, fb->height << 16,
-				    state->base.rotation);
-
-		/* sanity check to make sure the src viewport wasn't enlarged */
-		WARN_ON(src->x1 < (int) state->base.src_x ||
-			src->y1 < (int) state->base.src_y ||
-			src->x2 > (int) state->base.src_x + state->base.src_w ||
-			src->y2 > (int) state->base.src_y + state->base.src_h);
+		struct drm_rect *src = &state->base.src;
+		struct drm_rect *dst = &state->base.dst;
+		unsigned int crtc_w = drm_rect_width(dst);
+		unsigned int crtc_h = drm_rect_height(dst);
+		uint32_t src_x, src_y, src_w, src_h;
 
 		/*
 		 * Hardware doesn't handle subpixel coordinates.
@@ -1060,58 +1005,39 @@ intel_check_sprite_plane(struct intel_plane *plane,
 		src_y = src->y1 >> 16;
 		src_h = drm_rect_height(src) >> 16;
 
-		if (intel_format_is_yuv(fb->format->format)) {
-			src_x &= ~1;
-			src_w &= ~1;
-
-			/*
-			 * Must keep src and dst the
-			 * same if we can't scale.
-			 */
-			if (!can_scale)
-				crtc_w &= ~1;
+		src->x1 = src_x << 16;
+		src->x2 = (src_x + src_w) << 16;
+		src->y1 = src_y << 16;
+		src->y2 = (src_y + src_h) << 16;
 
-			if (crtc_w == 0)
-				state->base.visible = false;
+		if (intel_format_is_yuv(fb->format->format) &&
+		    (src_x % 2 || src_w % 2)) {
+			DRM_DEBUG_KMS("src x/w (%u, %u) must be a multiple of 2 for YUV planes\n",
+				      src_x, src_w);
+			return -EINVAL;
 		}
-	}
 
-	/* Check size restrictions when scaling */
-	if (state->base.visible && (src_w != crtc_w || src_h != crtc_h)) {
-		unsigned int width_bytes;
-		int cpp = fb->format->cpp[0];
+		/* Check size restrictions when scaling */
+		if (src_w != crtc_w || src_h != crtc_h) {
+			unsigned int width_bytes;
+			int cpp = fb->format->cpp[0];
 
-		WARN_ON(!can_scale);
+			WARN_ON(!can_scale);
 
-		/* FIXME interlacing min height is 6 */
+			width_bytes = ((src_x * cpp) & 63) + src_w * cpp;
 
-		if (crtc_w < 3 || crtc_h < 3)
-			state->base.visible = false;
-
-		if (src_w < 3 || src_h < 3)
-			state->base.visible = false;
-
-		width_bytes = ((src_x * cpp) & 63) + src_w * cpp;
-
-		if (INTEL_GEN(dev_priv) < 9 && (src_w > 2048 || src_h > 2048 ||
-		    width_bytes > 4096 || fb->pitches[0] > 4096)) {
-			DRM_DEBUG_KMS("Source dimensions exceed hardware limits\n");
-			return -EINVAL;
+			/* FIXME interlacing min height is 6 */
+			if (INTEL_GEN(dev_priv) < 9 && (
+			     src_w < 3 || src_h < 3 ||
+			     src_w > 2048 || src_h > 2048 ||
+			     crtc_w < 3 || crtc_h < 3 ||
+			     width_bytes > 4096 || fb->pitches[0] > 4096)) {
+				DRM_DEBUG_KMS("Source dimensions exceed hardware limits\n");
+				return -EINVAL;
+			}
 		}
 	}
 
-	if (state->base.visible) {
-		src->x1 = src_x << 16;
-		src->x2 = (src_x + src_w) << 16;
-		src->y1 = src_y << 16;
-		src->y2 = (src_y + src_h) << 16;
-	}
-
-	dst->x1 = crtc_x;
-	dst->x2 = crtc_x + crtc_w;
-	dst->y1 = crtc_y;
-	dst->y2 = crtc_y + crtc_h;
-
 	if (INTEL_GEN(dev_priv) >= 9) {
 		ret = skl_check_plane_surface(crtc_state, state);
 		if (ret)
-- 
2.17.0

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Re: [PATCH 2/3] drm/rect: Handle rounding errors in drm_rect_clip_scaled

[Daniel Vetter]

On Thu, Apr 26, 2018 at 10:28:20AM +0200, Maarten Lankhorst wrote:
> No matter how you perform the clip adjustments, a small
> error may push the scaling factor to the other side of
> 0x10000. Solve this with a macro that will fixup the
> scale to 0x10000 if we accidentally wrap to the other side.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

I think this and the previous patch are perfect candidates for in-kernel
selftests. Can I volunteer you to get those started for the kms side? We
already have a drm_mm selftest, but I think splitting things a bit might
be useful.

Or we rename that one and just stuff all the kms tests in there, dunno.
-Daniel

> ---
>  drivers/gpu/drm/drm_rect.c | 65 +++++++++++++++++++++++++++-----------
>  1 file changed, 47 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
> index b179c7c73cc5..71b6b7f5d58f 100644
> --- a/drivers/gpu/drm/drm_rect.c
> +++ b/drivers/gpu/drm/drm_rect.c
> @@ -50,6 +50,24 @@ bool drm_rect_intersect(struct drm_rect *r1, const struct drm_rect *r2)
>  }
>  EXPORT_SYMBOL(drm_rect_intersect);
>  
> +static int drm_calc_scale(int src, int dst)
> +{
> +	int scale = 0;
> +
> +	if (WARN_ON(src < 0 || dst < 0))
> +		return -EINVAL;
> +
> +	if (dst == 0)
> +		return 0;
> +
> +	if (src > (dst << 16))
> +		return DIV_ROUND_UP(src, dst);
> +	else
> +		scale = src / dst;
> +
> +	return scale;
> +}
> +
>  /**
>   * drm_rect_clip_scaled - perform a scaled clip operation
>   * @src: source window rectangle
> @@ -71,49 +89,60 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,
>  {
>  	int diff;
>  
> +	/*
> +	 * When scale is near 0x10000 rounding errors may cause the scaling
> +	 * factor to the other side. Some hardware may support
> +	 * upsampling, but not downsampling, and that would break when
> +	 * rounding.
> +	 */
> +#define FIXUP(oldscale, fn, m, second) do { \
> +	if (oldscale != 1 << 16) { \
> +		int newscale = drm_calc_scale(fn(src), fn(dst)); \
> + \
> +		if (newscale < 0) \
> +			return false; \
> + \
> +		if ((oldscale < 0x10000) != (newscale < 0x10000)) { \
> +			if (!second) \
> +				src->m##1 = src->m##2 - ((fn(dst) - diff) << 16); \
> +			else \
> +				src->m##2 = src->m##1 + ((fn(dst) - diff) << 16); \
> +		} \
> +	} \
> + } while (0)
> +
>  	diff = clip->x1 - dst->x1;
>  	if (diff > 0) {
>  		int64_t tmp = src->x1 + (int64_t) diff * hscale;
>  		src->x1 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(hscale, drm_rect_width, x, 0);
>  	}
> +
>  	diff = clip->y1 - dst->y1;
>  	if (diff > 0) {
>  		int64_t tmp = src->y1 + (int64_t) diff * vscale;
>  		src->y1 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(vscale, drm_rect_height, y, 0);
>  	}
> +
>  	diff = dst->x2 - clip->x2;
>  	if (diff > 0) {
>  		int64_t tmp = src->x2 - (int64_t) diff * hscale;
>  		src->x2 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(hscale, drm_rect_width, x, 1);
>  	}
>  	diff = dst->y2 - clip->y2;
>  	if (diff > 0) {
>  		int64_t tmp = src->y2 - (int64_t) diff * vscale;
>  		src->y2 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(vscale, drm_rect_height, y, 1);
>  	}
> +#undef FIXUP
>  
>  	return drm_rect_intersect(dst, clip);
>  }
>  EXPORT_SYMBOL(drm_rect_clip_scaled);
>  
> -static int drm_calc_scale(int src, int dst)
> -{
> -	int scale = 0;
> -
> -	if (WARN_ON(src < 0 || dst < 0))
> -		return -EINVAL;
> -
> -	if (dst == 0)
> -		return 0;
> -
> -	if (src > (dst << 16))
> -		return DIV_ROUND_UP(src, dst);
> -	else
> -		scale = src / dst;
> -
> -	return scale;
> -}
> -
>  /**
>   * drm_rect_calc_hscale - calculate the horizontal scaling factor
>   * @src: source window rectangle
> -- 
> 2.17.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 2/3] drm/rect: Handle rounding errors in drm_rect_clip_scaled

[Ville Syrjälä]

On Thu, Apr 26, 2018 at 10:28:20AM +0200, Maarten Lankhorst wrote:
> No matter how you perform the clip adjustments, a small
> error may push the scaling factor to the other side of
> 0x10000. Solve this with a macro that will fixup the
> scale to 0x10000 if we accidentally wrap to the other side.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_rect.c | 65 +++++++++++++++++++++++++++-----------
>  1 file changed, 47 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
> index b179c7c73cc5..71b6b7f5d58f 100644
> --- a/drivers/gpu/drm/drm_rect.c
> +++ b/drivers/gpu/drm/drm_rect.c
> @@ -50,6 +50,24 @@ bool drm_rect_intersect(struct drm_rect *r1, const struct drm_rect *r2)
>  }
>  EXPORT_SYMBOL(drm_rect_intersect);
>  
> +static int drm_calc_scale(int src, int dst)
> +{
> +	int scale = 0;
> +
> +	if (WARN_ON(src < 0 || dst < 0))
> +		return -EINVAL;
> +
> +	if (dst == 0)
> +		return 0;
> +
> +	if (src > (dst << 16))
> +		return DIV_ROUND_UP(src, dst);
> +	else
> +		scale = src / dst;
> +
> +	return scale;
> +}
> +
>  /**
>   * drm_rect_clip_scaled - perform a scaled clip operation
>   * @src: source window rectangle
> @@ -71,49 +89,60 @@ bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,
>  {
>  	int diff;
>  
> +	/*
> +	 * When scale is near 0x10000 rounding errors may cause the scaling
> +	 * factor to the other side. Some hardware may support
> +	 * upsampling, but not downsampling, and that would break when
> +	 * rounding.
> +	 */
> +#define FIXUP(oldscale, fn, m, second) do { \
> +	if (oldscale != 1 << 16) { \
> +		int newscale = drm_calc_scale(fn(src), fn(dst)); \
> + \
> +		if (newscale < 0) \
> +			return false; \
> + \
> +		if ((oldscale < 0x10000) != (newscale < 0x10000)) { \
> +			if (!second) \
> +				src->m##1 = src->m##2 - ((fn(dst) - diff) << 16); \
> +			else \
> +				src->m##2 = src->m##1 + ((fn(dst) - diff) << 16); \

This is starting to get very messy. Also are we sure the x2/y2 can't
go past the initial value here?

It's starting to feel like we should do the clip with the rounding the
orher way, which should guarantee we never flip between up and down
scaling by accident. And then just do a post-clip check for final scale
factor with the pessimistic rounding direction to make sure we stay
within the limits.

> +		} \
> +	} \
> + } while (0)
> +
>  	diff = clip->x1 - dst->x1;
>  	if (diff > 0) {
>  		int64_t tmp = src->x1 + (int64_t) diff * hscale;
>  		src->x1 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(hscale, drm_rect_width, x, 0);
>  	}
> +
>  	diff = clip->y1 - dst->y1;
>  	if (diff > 0) {
>  		int64_t tmp = src->y1 + (int64_t) diff * vscale;
>  		src->y1 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(vscale, drm_rect_height, y, 0);
>  	}
> +
>  	diff = dst->x2 - clip->x2;
>  	if (diff > 0) {
>  		int64_t tmp = src->x2 - (int64_t) diff * hscale;
>  		src->x2 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(hscale, drm_rect_width, x, 1);
>  	}
>  	diff = dst->y2 - clip->y2;
>  	if (diff > 0) {
>  		int64_t tmp = src->y2 - (int64_t) diff * vscale;
>  		src->y2 = clamp_t(int64_t, tmp, INT_MIN, INT_MAX);
> +		FIXUP(vscale, drm_rect_height, y, 1);
>  	}
> +#undef FIXUP
>  
>  	return drm_rect_intersect(dst, clip);
>  }
>  EXPORT_SYMBOL(drm_rect_clip_scaled);
>  
> -static int drm_calc_scale(int src, int dst)
> -{
> -	int scale = 0;
> -
> -	if (WARN_ON(src < 0 || dst < 0))
> -		return -EINVAL;
> -
> -	if (dst == 0)
> -		return 0;
> -
> -	if (src > (dst << 16))
> -		return DIV_ROUND_UP(src, dst);
> -	else
> -		scale = src / dst;
> -
> -	return scale;
> -}
> -
>  /**
>   * drm_rect_calc_hscale - calculate the horizontal scaling factor
>   * @src: source window rectangle
> -- 
> 2.17.0

-- 
Ville Syrjälä
Intel
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