dm: video: Add damage tracking API
We are going to introduce image damage tracking to fasten up screen
refresh on large displays. This patch adds damage tracking for up to
one rectangle of the screen which is typically enough to hold blt or
text print updates. Callers into this API and a reduced dcache flush
code path will follow in later patches.
Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reported-by: Da Xue <da@libre.computer>
[Alper: Use xstart/yend, document new fields, return void from
video_damage(), declare priv, drop headers, use IS_ENABLED()]
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/20230821135111.3558478-5-alpernebiyasak@gmail.com/
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 7335394..bc9c7c1 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -98,6 +98,19 @@
To use this, your video driver must set @copy_base in
struct video_uc_plat.
+config VIDEO_DAMAGE
+ bool "Enable damage tracking of frame buffer regions"
+ help
+ On some machines (most ARM), the display frame buffer resides in
+ RAM. To make the display controller pick up screen updates, we
+ have to flush frame buffer contents from CPU caches into RAM which
+ can be a slow operation.
+
+ This feature adds damage tracking to collect information about regions
+ that received updates. When we want to sync, we then only flush
+ regions of the frame buffer that were modified before, speeding up
+ screen refreshes significantly.
+
config BACKLIGHT_PWM
bool "Generic PWM based Backlight Driver"
depends on BACKLIGHT && DM_PWM
diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index c684c99..8e2edd7 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -369,6 +369,34 @@
priv->colour_bg = video_index_to_colour(priv, back);
}
+/* Notify about changes in the frame buffer */
+#ifdef CONFIG_VIDEO_DAMAGE
+void video_damage(struct udevice *vid, int x, int y, int width, int height)
+{
+ struct video_priv *priv = dev_get_uclass_priv(vid);
+ int xend = x + width;
+ int yend = y + height;
+
+ if (x > priv->xsize)
+ return;
+
+ if (y > priv->ysize)
+ return;
+
+ if (xend > priv->xsize)
+ xend = priv->xsize;
+
+ if (yend > priv->ysize)
+ yend = priv->ysize;
+
+ /* Span a rectangle across all old and new damage */
+ priv->damage.xstart = min(x, priv->damage.xstart);
+ priv->damage.ystart = min(y, priv->damage.ystart);
+ priv->damage.xend = max(xend, priv->damage.xend);
+ priv->damage.yend = max(yend, priv->damage.yend);
+}
+#endif
+
/* Flush video activity to the caches */
int video_sync(struct udevice *vid, bool force)
{
@@ -402,6 +430,13 @@
#endif
priv->last_sync = get_timer(0);
+ if (IS_ENABLED(CONFIG_VIDEO_DAMAGE)) {
+ priv->damage.xstart = priv->xsize;
+ priv->damage.ystart = priv->ysize;
+ priv->damage.xend = 0;
+ priv->damage.yend = 0;
+ }
+
return 0;
}