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Commit f96bdf56 authored by Maarten Lankhorst's avatar Maarten Lankhorst
Browse files

drm/rect: Handle rounding errors in drm_rect_clip_scaled, v3. 



Instead of relying on a scale which may increase rounding errors,
clip src by doing: src * (dst - clip) / dst and rounding the result
away from 1, so the new coordinates get closer to 1. We won't need
to fix up with a magic macro afterwards, because our scaling factor
will never go to the other side of 1.

Changes since v1:
- Adjust dst immediately, else drm_rect_width/height on dst gives bogus
  results.
Change since v2:
- Get rid of macros and use 64-bits math.

Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[mlankhorst: Add Villes comment, and rename newsrc to tmp. (Ville)]
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180503112217.37292-3-maarten.lankhorst@linux.intel.com
parent 6f96f200

drivers/gpu/drm/drm_atomic_helper.c

+1 −1
Original line number Diff line number Diff line
@@ -766,7 +766,7 @@ int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state, 
	if (crtc_state->enable)

		drm_mode_get_hv_timing(&crtc_state->mode, &clip.x2, &clip.y2);



	plane_state->visible = drm_rect_clip_scaled(src, dst, &clip, hscale, vscale);

	plane_state->visible = drm_rect_clip_scaled(src, dst, &clip);



	drm_rect_rotate_inv(src, fb->width << 16, fb->height << 16, rotation);

drivers/gpu/drm/drm_rect.c

+36 −13
Original line number Diff line number Diff line
@@ -50,13 +50,25 @@ 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)

{

	u64 tmp = mul_u32_u32(src, dst - clip);



	/*

	 * Round toward 1.0 when clipping so that we don't accidentally

	 * change upscaling to downscaling or vice versa.

	 */

	if (src < (dst << 16))

		return DIV_ROUND_UP_ULL(tmp, dst);

	else

		return DIV_ROUND_DOWN_ULL(tmp, dst);

}



/**

 * drm_rect_clip_scaled - perform a scaled clip operation

 * @src: source window rectangle

 * @dst: destination window rectangle

 * @clip: clip rectangle

 * @hscale: horizontal scaling factor

 * @vscale: vertical scaling factor

 *

 * Clip rectangle @dst by rectangle @clip. Clip rectangle @src by the

 * same amounts multiplied by @hscale and @vscale.
@@ -66,33 +78,44 @@ EXPORT_SYMBOL(drm_rect_intersect); 
 * %false otherwise

 */

bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,

			  const struct drm_rect *clip,

			  int hscale, int vscale)

			  const struct drm_rect *clip)

{

	int diff;



	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);

		u32 new_src_w = clip_scaled(drm_rect_width(src),

					    drm_rect_width(dst), diff);



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

		dst->x1 = clip->x1;

	}

	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);

		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);

		dst->y1 = clip->y1;

	}

	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);

		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);

		dst->x2 = clip->x2;

	}

	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);

		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);

		dst->y2 = clip->y2;

	}



	return drm_rect_intersect(dst, clip);

	return drm_rect_visible(dst);

}

EXPORT_SYMBOL(drm_rect_clip_scaled);

drivers/gpu/drm/i915/intel_sprite.c

+1 −1
Original line number Diff line number Diff line
@@ -1003,7 +1003,7 @@ intel_check_sprite_plane(struct intel_plane *plane, 
		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);

	state->base.visible = drm_rect_clip_scaled(src, dst, &clip);



	crtc_x = dst->x1;

	crtc_y = dst->y1;

include/drm/drm_rect.h

+1 −2
Original line number Diff line number Diff line
@@ -175,8 +175,7 @@ static inline bool drm_rect_equals(const struct drm_rect *r1, 


bool drm_rect_intersect(struct drm_rect *r, const struct drm_rect *clip);

bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,

			  const struct drm_rect *clip,

			  int hscale, int vscale);

			  const struct drm_rect *clip);

int drm_rect_calc_hscale(const struct drm_rect *src,

			 const struct drm_rect *dst,

			 int min_hscale, int max_hscale);