video: Use VIDEO_DAMAGE for VIDEO_COPY

CONFIG_VIDEO_COPY implemented a range-based copying mechanism: If we
print a single character, it will always copy the full range of bytes
from the top left corner of the character to the lower right onto the
uncached frame buffer. This includes pretty much the full line contents
of the printed character.

Since we now have proper damage tracking, let's make use of that to reduce
the amount of data we need to copy. With this patch applied, we will only
copy the tiny rectangle surrounding characters when we print them,
speeding up the video console.

After this, changes to the main frame buffer are not immediately copied
to the copy frame buffer, but postponed until the next video device
sync. So issue an explicit sync before inspecting the copy frame buffer
contents for the video tests.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
[Alper: Rebase for fontdata->height/w, fill_part(), fix memmove(dev),
        drop from defconfig, use damage.xstart/yend, use IS_ENABLED(),
        call video_sync() before copy_fb check, update video_copy test]
Co-developed-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Link: https://lore.kernel.org/u-boot/20230821135111.3558478-12-alpernebiyasak@gmail.com/
diff --git a/test/dm/video.c b/test/dm/video.c
index cf81b90..929fc16 100644
--- a/test/dm/video.c
+++ b/test/dm/video.c
@@ -105,6 +105,7 @@
 	if (!IS_ENABLED(CONFIG_VIDEO_COPY))
 		return 0;
 
+	video_sync(dev, false);
 	ut_assertf(!memcmp(priv->fb, priv->copy_fb, priv->fb_size),
 		   "Copy framebuffer does not match fb");
 
@@ -700,12 +701,22 @@
 
 	/*
 	 * We should have the full content on the main buffer, but only
-	 * the new content should have been copied to the copy buffer.
+	 * 'damage' should have been copied to the copy buffer. This consists
+	 * of a while rectangle with the Denx logo and four lines of text. The
+	 * rest of the display is black.
+	 *
+	 * An easy way to try this is by changing video_sync() to call
+	 * sandbox_sdl_sync(priv->copy_fb) instead of priv->fb then running the
+	 * unit test:
+	 *
+	 *   ./u-boot -Tl
+	 *   ut dm dm_test_video_copy
 	 */
 	vidconsole_put_string(con, test_string);
 	vidconsole_put_string(con, test_string);
+	video_sync(dev, true);
 	ut_asserteq(7589, compress_frame_buffer(uts, dev, false));
-	ut_asserteq(5278, compress_frame_buffer(uts, dev, true));
+	ut_asserteq(7704, compress_frame_buffer(uts, dev, true));
 
 	return 0;
 }