drm/format-helper: Convert drm_fb_swab() to struct iosys_map

Convert drm_fb_swab() to use struct iosys_map() and convert users. The
new interface supports multi-plane color formats, but implementation
only supports a single plane for now.

v2:
	* use drm_format_info_bpp() (Sam)
	* update documentation (Sam)
	* add TODO on vaddr location (Sam)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220808125406.20752-5-tzimmermann@suse.de

drivers/gpu/drm/drm_format_helper.c

@@ -205,37 +205,62 @@ static void drm_fb_swab32_line(void *dbuf, const void *sbuf, unsigned int pixels
 
 /**
  * drm_fb_swab - Swap bytes into clip buffer
- * @dst: Destination buffer
- * @dst_pitch: Number of bytes between two consecutive scanlines within dst
- * @src: Source buffer
+ * @dst: Array of destination buffers
+ * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
+ *             within @dst; can be NULL if scanlines are stored next to each other.
+ * @vmap: Array of source buffers
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  * @cached: Source buffer is mapped cached (eg. not write-combined)
  *
- * If @cached is false a temporary buffer is used to cache one pixel line at a
- * time to speed up slow uncached reads.
+ * This function copies parts of a framebuffer to display memory and swaps per-pixel
+ * bytes during the process. Destination and framebuffer formats must match. The
+ * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
+ * least as many entries as there are planes in @fb's format. Each entry stores the
+ * value for the format's respective color plane at the same index. If @cached is
+ * false a temporary buffer is used to cache one pixel line at a time to speed up
+ * slow uncached reads.
  *
- * This function does not apply clipping on dst, i.e. the destination
- * is at the top-left corner.
+ * This function does not apply clipping on @dst (i.e. the destination is at the
+ * top-left corner).
  */
-void drm_fb_swab(void *dst, unsigned int dst_pitch, const void *src,
-		 const struct drm_framebuffer *fb, const struct drm_rect *clip,
-		 bool cached)
+void drm_fb_swab(struct iosys_map *dst, const unsigned int *dst_pitch,
+		 const struct iosys_map *vmap, const struct drm_framebuffer *fb,
+		 const struct drm_rect *clip, bool cached)
 {
-	u8 cpp = fb->format->cpp[0];
+	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
+		0, 0, 0, 0
+	};
+	const struct drm_format_info *format = fb->format;
+	u8 cpp = DIV_ROUND_UP(drm_format_info_bpp(format, 0), 8);
+	void (*swab_line)(void *dbuf, const void *sbuf, unsigned int npixels);
 
 	switch (cpp) {
 	case 4:
-		drm_fb_xfrm(dst, dst_pitch, cpp, src, fb, clip, cached, drm_fb_swab32_line);
+		swab_line = drm_fb_swab32_line;
 		break;
 	case 2:
-		drm_fb_xfrm(dst, dst_pitch, cpp, src, fb, clip, cached, drm_fb_swab16_line);
+		swab_line = drm_fb_swab16_line;
 		break;
 	default:
 		drm_warn_once(fb->dev, "Format %p4cc has unsupported pixel size.\n",
-			      &fb->format->format);
+			      &format->format);
+		swab_line = NULL;
 		break;
 	}
+	if (!swab_line)
+		return;
+
+	if (!dst_pitch)
+		dst_pitch = default_dst_pitch;
+
+	/* TODO: handle vmap in I/O memory here */
+	if (dst->is_iomem)
+		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], cpp,
+				 vmap[0].vaddr, fb, clip, cached, swab_line);
+	else
+		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], cpp, vmap[0].vaddr, fb,
+			    clip, cached, swab_line);
 }
 EXPORT_SYMBOL(drm_fb_swab);
 

drivers/gpu/drm/drm_mipi_dbi.c

@@ -221,7 +221,7 @@ int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
 	switch (fb->format->format) {
 	case DRM_FORMAT_RGB565:
 		if (swap)
-			drm_fb_swab(dst, 0, src, fb, clip, !gem->import_attach);
+			drm_fb_swab(&dst_map, NULL, data, fb, clip, !gem->import_attach);
 		else
 			drm_fb_memcpy(&dst_map, NULL, data, fb, clip);
 		break;

drivers/gpu/drm/gud/gud_pipe.c

@@ -205,7 +205,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
 			len = gud_xrgb8888_to_color(buf, format, vaddr, fb, rect);
 		}
 	} else if (gud_is_big_endian() && format->cpp[0] > 1) {
-		drm_fb_swab(buf, 0, vaddr, fb, rect, !import_attach);
+		drm_fb_swab(&dst, NULL, map_data, fb, rect, !import_attach);
 	} else if (compression && !import_attach && pitch == fb->pitches[0]) {
 		/* can compress directly from the framebuffer */
 		buf = vaddr + rect->y1 * pitch;

include/drm/drm_format_helper.h

@@ -17,9 +17,9 @@ unsigned int drm_fb_clip_offset(unsigned int pitch, const struct drm_format_info
 void drm_fb_memcpy(struct iosys_map *dst, const unsigned int *dst_pitch,
 		   const struct iosys_map *vmap, const struct drm_framebuffer *fb,
 		   const struct drm_rect *clip);
-void drm_fb_swab(void *dst, unsigned int dst_pitch, const void *src,
-		 const struct drm_framebuffer *fb, const struct drm_rect *clip,
-		 bool cached);
+void drm_fb_swab(struct iosys_map *dst, const unsigned int *dst_pitch,
+		 const struct iosys_map *vmap, const struct drm_framebuffer *fb,
+		 const struct drm_rect *clip, bool cached);
 void drm_fb_xrgb8888_to_rgb332(void *dst, unsigned int dst_pitch, const void *vaddr,
 			       const struct drm_framebuffer *fb, const struct drm_rect *clip);
 void drm_fb_xrgb8888_to_rgb565(void *dst, unsigned int dst_pitch, const void *vaddr,