[PATCH v3 0/7] Add video damage tracking

[PATCH v3 0/7] Add video damage tracking

[Alexander Graf]

This patch set speeds up graphics output on ARM by a factor of 60x.

On most ARM SBCs, we keep the frame buffer in DRAM and map it as cached,
but need it accessible by the display controller which reads directly
from a later point of consistency. Hence, we flush the frame buffer to
DRAM on every change. The full frame buffer.

Unfortunately, with the advent of 4k displays, we are seeing frame buffers
that can take a while to flush out. This was reported by Da Xue with grub,
which happily print 1000s of spaces on the screen to draw a menu. Every
printed space triggers a cache flush.

This patch set implements the easiest mitigation against this problem:
Damage tracking. We remember the lowest common denominator region that was
touched since the last video_sync() call and only flush that. The most
typical writer to the frame buffer is the video console, which always
writes rectangles of characters on the screen and syncs afterwards.

With this patch set applied, we reduce drawing a large grub menu (with
serial console attached for size information) on an RK3399-ROC system
at 1440p from 55 seconds to less than 1 second.

Version 2 also implements VIDEO_COPY using this mechanism, reducing its
overhead compared to before as well. So even x86 systems should be faster
with this now :).


Alternatives considered:

  1) Lazy sync - Sandbox does this. It only calls video_sync(true) ever
     so often. We are missing timers to do this generically.

  2) Double buffering - We could try to identify whether anything changed
     at all and only draw to the FB if it did. That would require
     maintaining a second buffer that we need to scan.

  3) Text buffer - Maintain a buffer of all text printed on the screen with
     respective location. Don't write if the old and new character are
     identical. This would limit applicability to text only and is an
     optimization on top of this patch set.

  4) Hash screen lines - Create a hash (sha256?) over every line when it
     changes. Only flush when it does. I'm not sure if this would waste
     more time, memory and cache than the current approach. It would make
     full screen updates much more expensive.

v1 -> v2:

  - new patch: video: Use VIDEO_DAMAGE for VIDEO_COPY
  - Remove ifdefs
  - Fix dcache range; we were flushing too much before
  - Fix ranges in truetype target
  - Limit rotate to necessary damange

v2 -> v3:

  - Rebase
  - Adapt to DM_VIDEO always
  - Make CONFIG_COPY always select VIDEO_DAMAGE

Alexander Graf (7):
  dm: video: Add damage tracking API
  dm: video: Add damage notification on display clear
  vidconsole: Add damage notifications to all vidconsole drivers
  video: Add damage notification on bmp display
  efi_loader: GOP: Add damage notification on BLT
  video: Only dcache flush damaged lines
  video: Use VIDEO_DAMAGE for VIDEO_COPY

 drivers/video/Kconfig             |  19 +++
 drivers/video/console_normal.c    |  22 ++--
 drivers/video/console_rotate.c    |  87 +++++++++-----
 drivers/video/console_truetype.c  |  30 ++---
 drivers/video/vidconsole-uclass.c |  16 ---
 drivers/video/video-uclass.c      | 185 ++++++++++++++++++------------
 drivers/video/video_bmp.c         |   7 +-
 include/video.h                   |  54 ++++-----
 include/video_console.h           |  49 --------
 lib/efi_loader/efi_gop.c          |   4 +
 10 files changed, 238 insertions(+), 235 deletions(-)

-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 1/7] dm: video: Add damage tracking API

[Alexander Graf]

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>

---

v1 -> v2:

  - Remove ifdefs

v2 -> v3:

  - Adapt Kconfig to DM always
---
 drivers/video/Kconfig        | 14 ++++++++++++
 drivers/video/video-uclass.c | 41 ++++++++++++++++++++++++++++++++++++
 include/video.h              | 29 +++++++++++++++++++++++--
 3 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index f539977d9b..e12457c654 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -62,6 +62,20 @@ config VIDEO_COPY
 	  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"
+	default y if ARM && !SYS_DCACHE_OFF
+	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 0ce376ca3f..48a053841e 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -21,6 +21,8 @@
 #include <dm/device_compat.h>
 #include <dm/device-internal.h>
 #include <dm/uclass-internal.h>
+#include <linux/types.h>
+#include <linux/bitmap.h>
 #ifdef CONFIG_SANDBOX
 #include <asm/sdl.h>
 #endif
@@ -254,6 +256,45 @@ void video_set_default_colors(struct udevice *dev, bool invert)
 	priv->colour_bg = video_index_to_colour(priv, back);
 }
 
+/* Notify about changes in the frame buffer */
+int video_damage(struct udevice *vid, int x, int y, int width, int height)
+{
+	struct video_priv *priv = dev_get_uclass_priv(vid);
+	int endx = x + width;
+	int endy = y + height;
+
+	if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE))
+		return 0;
+
+	if (x > priv->xsize)
+		return 0;
+
+	if (y > priv->ysize)
+		return 0;
+
+	if (endx > priv->xsize)
+		endx = priv->xsize;
+
+	if (endy > priv->ysize)
+		endy = priv->ysize;
+
+	if (priv->damage.endx && priv->damage.endy) {
+		/* Span a rectangle across all old and new damage */
+		priv->damage.x = min(x, priv->damage.x);
+		priv->damage.y = min(y, priv->damage.y);
+		priv->damage.endx = max(endx, priv->damage.endx);
+		priv->damage.endy = max(endy, priv->damage.endy);
+	} else {
+		/* First damage, setting the rectangle to span it */
+		priv->damage.x = x;
+		priv->damage.y = y;
+		priv->damage.endx = endx;
+		priv->damage.endy = endy;
+	}
+
+	return 0;
+}
+
 /* Flush video activity to the caches */
 int video_sync(struct udevice *vid, bool force)
 {
diff --git a/include/video.h b/include/video.h
index 43f2e2c02f..4b35e97f79 100644
--- a/include/video.h
+++ b/include/video.h
@@ -109,6 +109,12 @@ struct video_priv {
 	void *fb;
 	int fb_size;
 	void *copy_fb;
+	struct {
+		int x;
+		int y;
+		int endx;
+		int endy;
+	} damage;
 	int line_length;
 	u32 colour_fg;
 	u32 colour_bg;
@@ -211,8 +217,9 @@ int video_fill(struct udevice *dev, u32 colour);
  * @return: 0 on success, error code otherwise
  *
  * Some frame buffers are cached or have a secondary frame buffer. This
- * function syncs these up so that the current contents of the U-Boot frame
- * buffer are displayed to the user.
+ * function syncs the damaged parts of them up so that the current contents
+ * of the U-Boot frame buffer are displayed to the user. It clears the damage
+ * buffer.
  */
 int video_sync(struct udevice *vid, bool force);
 
@@ -332,6 +339,24 @@ static inline int video_sync_copy_all(struct udevice *dev)
 
 #endif
 
+/**
+ * video_damage() - Notify the video subsystem about screen updates.
+ *
+ * @vid:	Device to sync
+ * @x:	        Upper left X coordinate of the damaged rectangle
+ * @y:	        Upper left Y coordinate of the damaged rectangle
+ * @width:	Width of the damaged rectangle
+ * @height:	Height of the damaged rectangle
+ *
+ * @return: 0
+ *
+ * Some frame buffers are cached or have a secondary frame buffer. This
+ * function notifies the video subsystem about rectangles that were updated
+ * within the frame buffer. They may only get written to the screen on the
+ * next call to video_sync().
+ */
+int video_damage(struct udevice *vid, int x, int y, int width, int height);
+
 /**
  * video_is_active() - Test if one video device it active
  *
-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 2/7] dm: video: Add damage notification on display clear

[Alexander Graf]

Let's report the video damage when we clear the screen. This
way we can later lazily flush only relevant regions to hardware.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reported-by: Da Xue <da@libre.computer>
---
 drivers/video/video-uclass.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index 48a053841e..f1fbeaadcb 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -160,6 +160,8 @@ int video_fill(struct udevice *dev, u32 colour)
 	if (ret)
 		return ret;
 
+	video_damage(dev, 0, 0, priv->xsize, priv->ysize);
+
 	return video_sync(dev, false);
 }
 
-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 3/7] vidconsole: Add damage notifications to all vidconsole drivers

[Alexander Graf]

Now that we have a damage tracking API, let's populate damage done by
vidconsole drivers. We try to declare as little memory as damaged as
possible, with the exception of rotated screens that I couldn't get my
head wrapped around. On those, we revert to the old behavior and mark
the full screen as damaged on every update.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reported-by: Da Xue <da@libre.computer>

---

v1 -> v2:

  - Fix ranges in truetype target
  - Limit rotate to necessary damange
---
 drivers/video/console_normal.c   | 10 ++++++
 drivers/video/console_rotate.c   | 54 ++++++++++++++++++++++++++++++++
 drivers/video/console_truetype.c | 15 +++++++++
 3 files changed, 79 insertions(+)

diff --git a/drivers/video/console_normal.c b/drivers/video/console_normal.c
index 04f022491e..5b5586fd3e 100644
--- a/drivers/video/console_normal.c
+++ b/drivers/video/console_normal.c
@@ -57,6 +57,9 @@ static int console_normal_set_row(struct udevice *dev, uint row, int clr)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent, 0, VIDEO_FONT_HEIGHT * row, vid_priv->xsize,
+		     VIDEO_FONT_HEIGHT);
+
 	return 0;
 }
 
@@ -76,6 +79,9 @@ static int console_normal_move_rows(struct udevice *dev, uint rowdst,
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent, 0, VIDEO_FONT_HEIGHT * rowdst, vid_priv->xsize,
+		     VIDEO_FONT_HEIGHT * count);
+
 	return 0;
 }
 
@@ -143,6 +149,10 @@ static int console_normal_putc_xy(struct udevice *dev, uint x_frac, uint y,
 		}
 		line += vid_priv->line_length;
 	}
+
+	video_damage(dev->parent, VID_TO_PIXEL(x_frac), y, VIDEO_FONT_WIDTH,
+		     VIDEO_FONT_HEIGHT);
+
 	ret = vidconsole_sync_copy(dev, start, line);
 	if (ret)
 		return ret;
diff --git a/drivers/video/console_rotate.c b/drivers/video/console_rotate.c
index 36c8d0609d..56e20bb4f3 100644
--- a/drivers/video/console_rotate.c
+++ b/drivers/video/console_rotate.c
@@ -57,6 +57,12 @@ static int console_set_row_1(struct udevice *dev, uint row, int clr)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent,
+		     vid_priv->xsize - ((row + 1) * VIDEO_FONT_HEIGHT),
+		     0,
+		     VIDEO_FONT_HEIGHT,
+		     vid_priv->ysize);
+
 	return 0;
 }
 
@@ -83,6 +89,12 @@ static int console_move_rows_1(struct udevice *dev, uint rowdst, uint rowsrc,
 		dst += vid_priv->line_length;
 	}
 
+	video_damage(dev->parent,
+		     vid_priv->xsize - ((rowdst + count) * VIDEO_FONT_HEIGHT),
+		     0,
+		     count * VIDEO_FONT_HEIGHT,
+		     vid_priv->ysize);
+
 	return 0;
 }
 
@@ -150,6 +162,12 @@ static int console_putc_xy_1(struct udevice *dev, uint x_frac, uint y, char ch)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent,
+		     vid_priv->xsize - y - VIDEO_FONT_HEIGHT - 1,
+		     linenum - 1,
+		     VIDEO_FONT_HEIGHT,
+		     VIDEO_FONT_WIDTH);
+
 	return VID_TO_POS(VIDEO_FONT_WIDTH);
 }
 
@@ -199,6 +217,12 @@ static int console_set_row_2(struct udevice *dev, uint row, int clr)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent,
+		     0,
+		     vid_priv->ysize - (row + 1) * VIDEO_FONT_HEIGHT,
+		     vid_priv->xsize,
+		     VIDEO_FONT_HEIGHT);
+
 	return 0;
 }
 
@@ -218,6 +242,12 @@ static int console_move_rows_2(struct udevice *dev, uint rowdst, uint rowsrc,
 	vidconsole_memmove(dev, dst, src,
 			   VIDEO_FONT_HEIGHT * vid_priv->line_length * count);
 
+	video_damage(dev->parent,
+		     0,
+		     vid_priv->ysize - (rowdst + count) * VIDEO_FONT_HEIGHT,
+		     vid_priv->xsize,
+		     count * VIDEO_FONT_HEIGHT);
+
 	return 0;
 }
 
@@ -288,6 +318,12 @@ static int console_putc_xy_2(struct udevice *dev, uint x_frac, uint y, char ch)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent,
+		     x - VIDEO_FONT_WIDTH,
+		     linenum - VIDEO_FONT_HEIGHT + 1,
+		     VIDEO_FONT_WIDTH,
+		     VIDEO_FONT_HEIGHT);
+
 	return VID_TO_POS(VIDEO_FONT_WIDTH);
 }
 
@@ -335,6 +371,12 @@ static int console_set_row_3(struct udevice *dev, uint row, int clr)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent,
+		     row * VIDEO_FONT_HEIGHT,
+		     0,
+		     VIDEO_FONT_HEIGHT,
+		     vid_priv->ysize);
+
 	return 0;
 }
 
@@ -359,6 +401,12 @@ static int console_move_rows_3(struct udevice *dev, uint rowdst, uint rowsrc,
 		dst += vid_priv->line_length;
 	}
 
+	video_damage(dev->parent,
+		     rowdst * VIDEO_FONT_HEIGHT,
+		     0,
+		     count * VIDEO_FONT_HEIGHT,
+		     vid_priv->ysize);
+
 	return 0;
 }
 
@@ -424,6 +472,12 @@ static int console_putc_xy_3(struct udevice *dev, uint x_frac, uint y, char ch)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent,
+		     y,
+		     x - VIDEO_FONT_WIDTH + 1,
+		     VIDEO_FONT_HEIGHT,
+		     VIDEO_FONT_WIDTH);
+
 	return VID_TO_POS(VIDEO_FONT_WIDTH);
 }
 
diff --git a/drivers/video/console_truetype.c b/drivers/video/console_truetype.c
index 6859c9fa11..3fc6e24485 100644
--- a/drivers/video/console_truetype.c
+++ b/drivers/video/console_truetype.c
@@ -145,6 +145,7 @@ struct console_tt_priv {
 static int console_truetype_set_row(struct udevice *dev, uint row, int clr)
 {
 	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
+	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	struct console_tt_metrics *met = priv->cur_met;
 	void *end, *line;
@@ -188,6 +189,9 @@ static int console_truetype_set_row(struct udevice *dev, uint row, int clr)
 	if (ret)
 		return ret;
 
+	video_damage(dev->parent, 0, vc_priv->y_charsize * row, vid_priv->xsize,
+		     vc_priv->y_charsize);
+
 	return 0;
 }
 
@@ -195,6 +199,7 @@ static int console_truetype_move_rows(struct udevice *dev, uint rowdst,
 				     uint rowsrc, uint count)
 {
 	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
+	struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
 	struct console_tt_priv *priv = dev_get_priv(dev);
 	struct console_tt_metrics *met = priv->cur_met;
 	void *dst;
@@ -213,6 +218,9 @@ static int console_truetype_move_rows(struct udevice *dev, uint rowdst,
 	for (i = 0; i < priv->pos_ptr; i++)
 		priv->pos[i].ypos -= diff;
 
+	video_damage(dev->parent, 0, vc_priv->y_charsize * rowdst, vid_priv->xsize,
+		     vc_priv->y_charsize * count);
+
 	return 0;
 }
 
@@ -370,6 +378,10 @@ static int console_truetype_putc_xy(struct udevice *dev, uint x, uint y,
 
 		line += vid_priv->line_length;
 	}
+
+	video_damage(dev->parent, VID_TO_PIXEL(x) + xoff,
+		     y + priv->baseline + yoff, width, height);
+
 	ret = vidconsole_sync_copy(dev, start, line);
 	if (ret)
 		return ret;
@@ -437,6 +449,9 @@ static int console_truetype_erase(struct udevice *dev, int xstart, int ystart,
 		}
 		line += vid_priv->line_length;
 	}
+
+	video_damage(dev->parent, xstart, ystart, xend - xstart, yend - ystart);
+
 	ret = vidconsole_sync_copy(dev, start, line);
 	if (ret)
 		return ret;
-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 4/7] video: Add damage notification on bmp display

[Alexander Graf]

Let's report the video damage when we draw a bitmap on the screen. This
way we can later lazily flush only relevant regions to hardware.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reported-by: Da Xue <da@libre.computer>
---
 drivers/video/video_bmp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/video_bmp.c b/drivers/video/video_bmp.c
index 6188a13e44..7dc5b011a8 100644
--- a/drivers/video/video_bmp.c
+++ b/drivers/video/video_bmp.c
@@ -424,6 +424,8 @@ int video_bmp_display(struct udevice *dev, ulong bmp_image, int x, int y,
 		break;
 	};
 
+	video_damage(dev, x, y, width, height);
+
 	/* Find the position of the top left of the image in the framebuffer */
 	fb = (uchar *)(priv->fb + y * priv->line_length + x * bpix / 8);
 	ret = video_sync_copy(dev, start, fb);
-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 5/7] efi_loader: GOP: Add damage notification on BLT

[Alexander Graf]

Now that we have a damage tracking API, let's populate damage done by
UEFI payloads when they BLT data onto the screen.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reported-by: Da Xue <da@libre.computer>

---

v1 -> v2:

  - Remove ifdefs from gop

v2 -> v3:

  - Adapt to always assume DM is used
---
 lib/efi_loader/efi_gop.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/efi_loader/efi_gop.c b/lib/efi_loader/efi_gop.c
index d1dc2f22d0..c80d307cbf 100644
--- a/lib/efi_loader/efi_gop.c
+++ b/lib/efi_loader/efi_gop.c
@@ -32,6 +32,7 @@ struct efi_gop_obj {
 	struct efi_gop ops;
 	struct efi_gop_mode_info info;
 	struct efi_gop_mode mode;
+	struct udevice *vdev;
 	/* Fields we only have access to during init */
 	u32 bpix;
 	void *fb;
@@ -243,6 +244,8 @@ static __always_inline efi_status_t gop_blt_int(struct efi_gop *this,
 		dlineoff += dwidth;
 	}
 
+	video_damage(gopobj->vdev, dx, dy, width, height);
+
 	return EFI_SUCCESS;
 }
 
@@ -547,6 +550,7 @@ efi_status_t efi_gop_register(void)
 	gopobj->info.pixels_per_scanline = col;
 	gopobj->bpix = bpix;
 	gopobj->fb = fb;
+	gopobj->vdev = vdev;
 
 	return EFI_SUCCESS;
 }
-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 6/7] video: Only dcache flush damaged lines

[Alexander Graf]

Now that we have a damage area tells us which parts of the frame buffer
actually need updating, let's only dcache flush those on video_sync()
calls. With this optimization in place, frame buffer updates - especially
on large screen such as 4k displays - speed up significantly.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reported-by: Da Xue <da@libre.computer>

---

v1 -> v2:

  - Fix dcache range; we were flushing too much before
  - Remove ifdefs
---
 drivers/video/video-uclass.c | 51 ++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index f1fbeaadcb..bf93f524c7 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -297,9 +297,45 @@ int video_damage(struct udevice *vid, int x, int y, int width, int height)
 	return 0;
 }
 
+#if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
+static void video_flush_dcache(struct udevice *vid)
+{
+	struct video_priv *priv = dev_get_uclass_priv(vid);
+
+	if (!priv->flush_dcache)
+		return;
+
+	if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
+		flush_dcache_range((ulong)priv->fb,
+				   ALIGN((ulong)priv->fb + priv->fb_size,
+					 CONFIG_SYS_CACHELINE_SIZE));
+
+		return;
+	}
+
+	if (priv->damage.endx && priv->damage.endy) {
+		int lstart = priv->damage.x * VNBYTES(priv->bpix);
+		int lend = priv->damage.endx * VNBYTES(priv->bpix);
+		int y;
+
+		for (y = priv->damage.y; y < priv->damage.endy; y++) {
+			ulong fb = (ulong)priv->fb;
+			ulong start = fb + (y * priv->line_length) + lstart;
+			ulong end = start + lend - lstart;
+
+			start = ALIGN_DOWN(start, CONFIG_SYS_CACHELINE_SIZE);
+			end = ALIGN(end, CONFIG_SYS_CACHELINE_SIZE);
+
+			flush_dcache_range(start, end);
+		}
+	}
+}
+#endif
+
 /* Flush video activity to the caches */
 int video_sync(struct udevice *vid, bool force)
 {
+	struct video_priv *priv = dev_get_uclass_priv(vid);
 	struct video_ops *ops = video_get_ops(vid);
 	int ret;
 
@@ -315,15 +351,8 @@ int video_sync(struct udevice *vid, bool force)
 	 * out whether it exists? For now, ARM is safe.
 	 */
 #if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
-	struct video_priv *priv = dev_get_uclass_priv(vid);
-
-	if (priv->flush_dcache) {
-		flush_dcache_range((ulong)priv->fb,
-				   ALIGN((ulong)priv->fb + priv->fb_size,
-					 CONFIG_SYS_CACHELINE_SIZE));
-	}
+	video_flush_dcache(vid);
 #elif defined(CONFIG_VIDEO_SANDBOX_SDL)
-	struct video_priv *priv = dev_get_uclass_priv(vid);
 	static ulong last_sync;
 
 	if (force || get_timer(last_sync) > 100) {
@@ -331,6 +360,12 @@ int video_sync(struct udevice *vid, bool force)
 		last_sync = get_timer(0);
 	}
 #endif
+
+	if (CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
+		priv->damage.endx = 0;
+		priv->damage.endy = 0;
+	}
+
 	return 0;
 }
 
-- 
2.37.1 (Apple Git-137.1)

[PATCH v3 7/7] video: Use VIDEO_DAMAGE for VIDEO_COPY

[Alexander Graf]

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.

As a bonus, we remove a lot of code.

Signed-off-by: Alexander Graf <agraf@csgraf.de>

---

v2 -> v3:

  - Rebase
  - Make CONFIG_COPY always select VIDEO_DAMAGE
---
 drivers/video/Kconfig             |  5 ++
 drivers/video/console_normal.c    | 14 +----
 drivers/video/console_rotate.c    | 37 ++-----------
 drivers/video/console_truetype.c  | 17 +-----
 drivers/video/vidconsole-uclass.c | 16 ------
 drivers/video/video-uclass.c      | 91 ++++++++-----------------------
 drivers/video/video_bmp.c         |  7 ---
 include/video.h                   | 37 -------------
 include/video_console.h           | 49 -----------------
 9 files changed, 37 insertions(+), 236 deletions(-)

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index e12457c654..2fbf9e9d5b 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -53,11 +53,14 @@ config VIDEO_PCI_DEFAULT_FB_SIZE
 
 config VIDEO_COPY
 	bool "Enable copying the frame buffer to a hardware copy"
+	select VIDEO_DAMAGE
 	help
 	  On some machines (e.g. x86), reading from the frame buffer is very
 	  slow because it is uncached. To improve performance, this feature
 	  allows the frame buffer to be kept in cached memory (allocated by
 	  U-Boot) and then copied to the hardware frame-buffer as needed.
+	  It uses the VIDEO_DAMAGE feature to keep track of regions to copy
+	  and will only copy actually touched regions.
 
 	  To use this, your video driver must set @copy_base in
 	  struct video_uc_plat.
@@ -76,6 +79,8 @@ config VIDEO_DAMAGE
 	  regions of the frame buffer that were modified before, speeding up
 	  screen refreshes significantly.
 
+	  It is also used by VIDEO_COPY to identify which regions changed.
+
 config BACKLIGHT_PWM
 	bool "Generic PWM based Backlight Driver"
 	depends on BACKLIGHT && DM_PWM
diff --git a/drivers/video/console_normal.c b/drivers/video/console_normal.c
index 5b5586fd3e..625d14516f 100644
--- a/drivers/video/console_normal.c
+++ b/drivers/video/console_normal.c
@@ -18,7 +18,6 @@ static int console_normal_set_row(struct udevice *dev, uint row, int clr)
 	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
 	void *line, *end;
 	int pixels = VIDEO_FONT_HEIGHT * vid_priv->xsize;
-	int ret;
 	int i;
 
 	line = vid_priv->fb + row * VIDEO_FONT_HEIGHT * vid_priv->line_length;
@@ -53,9 +52,6 @@ static int console_normal_set_row(struct udevice *dev, uint row, int clr)
 	default:
 		return -ENOSYS;
 	}
-	ret = vidconsole_sync_copy(dev, line, end);
-	if (ret)
-		return ret;
 
 	video_damage(dev->parent, 0, VIDEO_FONT_HEIGHT * row, vid_priv->xsize,
 		     VIDEO_FONT_HEIGHT);
@@ -70,14 +66,11 @@ static int console_normal_move_rows(struct udevice *dev, uint rowdst,
 	void *dst;
 	void *src;
 	int size;
-	int ret;
 
 	dst = vid_priv->fb + rowdst * VIDEO_FONT_HEIGHT * vid_priv->line_length;
 	src = vid_priv->fb + rowsrc * VIDEO_FONT_HEIGHT * vid_priv->line_length;
 	size = VIDEO_FONT_HEIGHT * vid_priv->line_length * count;
-	ret = vidconsole_memmove(dev, dst, src, size);
-	if (ret)
-		return ret;
+	memmove(dst, src, size);
 
 	video_damage(dev->parent, 0, VIDEO_FONT_HEIGHT * rowdst, vid_priv->xsize,
 		     VIDEO_FONT_HEIGHT * count);
@@ -94,7 +87,6 @@ static int console_normal_putc_xy(struct udevice *dev, uint x_frac, uint y,
 	int i, row;
 	void *start;
 	void *line;
-	int ret;
 
 	start = vid_priv->fb + y * vid_priv->line_length +
 		VID_TO_PIXEL(x_frac) * VNBYTES(vid_priv->bpix);
@@ -153,10 +145,6 @@ static int console_normal_putc_xy(struct udevice *dev, uint x_frac, uint y,
 	video_damage(dev->parent, VID_TO_PIXEL(x_frac), y, VIDEO_FONT_WIDTH,
 		     VIDEO_FONT_HEIGHT);
 
-	ret = vidconsole_sync_copy(dev, start, line);
-	if (ret)
-		return ret;
-
 	return VID_TO_POS(VIDEO_FONT_WIDTH);
 }
 
diff --git a/drivers/video/console_rotate.c b/drivers/video/console_rotate.c
index 56e20bb4f3..9b179a45b6 100644
--- a/drivers/video/console_rotate.c
+++ b/drivers/video/console_rotate.c
@@ -53,9 +53,6 @@ static int console_set_row_1(struct udevice *dev, uint row, int clr)
 		}
 		line += vid_priv->line_length;
 	}
-	ret = vidconsole_sync_copy(dev, start, line);
-	if (ret)
-		return ret;
 
 	video_damage(dev->parent,
 		     vid_priv->xsize - ((row + 1) * VIDEO_FONT_HEIGHT),
@@ -81,10 +78,7 @@ static int console_move_rows_1(struct udevice *dev, uint rowdst, uint rowsrc,
 		(rowsrc + count) * VIDEO_FONT_HEIGHT * pbytes;
 
 	for (j = 0; j < vid_priv->ysize; j++) {
-		ret = vidconsole_memmove(dev, dst, src,
-					 VIDEO_FONT_HEIGHT * pbytes * count);
-		if (ret)
-			return ret;
+		memmove(dst, src, VIDEO_FONT_HEIGHT * pbytes * count);
 		src += vid_priv->line_length;
 		dst += vid_priv->line_length;
 	}
@@ -158,10 +152,6 @@ static int console_putc_xy_1(struct udevice *dev, uint x_frac, uint y, char ch)
 		mask >>= 1;
 	}
 	/* We draw backwards from 'start, so account for the first line */
-	ret = vidconsole_sync_copy(dev, start - vid_priv->line_length, line);
-	if (ret)
-		return ret;
-
 	video_damage(dev->parent,
 		     vid_priv->xsize - y - VIDEO_FONT_HEIGHT - 1,
 		     linenum - 1,
@@ -213,9 +203,6 @@ static int console_set_row_2(struct udevice *dev, uint row, int clr)
 	default:
 		return -ENOSYS;
 	}
-	ret = vidconsole_sync_copy(dev, start, end);
-	if (ret)
-		return ret;
 
 	video_damage(dev->parent,
 		     0,
@@ -239,8 +226,8 @@ static int console_move_rows_2(struct udevice *dev, uint rowdst, uint rowsrc,
 		vid_priv->line_length;
 	src = end - (rowsrc + count) * VIDEO_FONT_HEIGHT *
 		vid_priv->line_length;
-	vidconsole_memmove(dev, dst, src,
-			   VIDEO_FONT_HEIGHT * vid_priv->line_length * count);
+	memmove(dev, dst, src, VIDEO_FONT_HEIGHT *
+		vid_priv->line_length * count);
 
 	video_damage(dev->parent,
 		     0,
@@ -313,10 +300,6 @@ static int console_putc_xy_2(struct udevice *dev, uint x_frac, uint y, char ch)
 		}
 		line -= vid_priv->line_length;
 	}
-	/* Add 4 bytes to allow for the first pixel writen */
-	ret = vidconsole_sync_copy(dev, start + 4, line);
-	if (ret)
-		return ret;
 
 	video_damage(dev->parent,
 		     x - VIDEO_FONT_WIDTH,
@@ -367,9 +350,6 @@ static int console_set_row_3(struct udevice *dev, uint row, int clr)
 		}
 		line += vid_priv->line_length;
 	}
-	ret = vidconsole_sync_copy(dev, start, line);
-	if (ret)
-		return ret;
 
 	video_damage(dev->parent,
 		     row * VIDEO_FONT_HEIGHT,
@@ -387,16 +367,13 @@ static int console_move_rows_3(struct udevice *dev, uint rowdst, uint rowsrc,
 	int pbytes = VNBYTES(vid_priv->bpix);
 	void *dst;
 	void *src;
-	int j, ret;
+	int j;
 
 	dst = vid_priv->fb + rowdst * VIDEO_FONT_HEIGHT * pbytes;
 	src = vid_priv->fb + rowsrc * VIDEO_FONT_HEIGHT * pbytes;
 
 	for (j = 0; j < vid_priv->ysize; j++) {
-		ret = vidconsole_memmove(dev, dst, src,
-					 VIDEO_FONT_HEIGHT * pbytes * count);
-		if (ret)
-			return ret;
+		memmove(dev, dst, src, VIDEO_FONT_HEIGHT * pbytes * count);
 		src += vid_priv->line_length;
 		dst += vid_priv->line_length;
 	}
@@ -468,10 +445,6 @@ static int console_putc_xy_3(struct udevice *dev, uint x_frac, uint y, char ch)
 		mask >>= 1;
 	}
 	/* Add a line to allow for the first pixels writen */
-	ret = vidconsole_sync_copy(dev, start + vid_priv->line_length, line);
-	if (ret)
-		return ret;
-
 	video_damage(dev->parent,
 		     y,
 		     x - VIDEO_FONT_WIDTH + 1,
diff --git a/drivers/video/console_truetype.c b/drivers/video/console_truetype.c
index 3fc6e24485..a545189cbd 100644
--- a/drivers/video/console_truetype.c
+++ b/drivers/video/console_truetype.c
@@ -185,9 +185,6 @@ static int console_truetype_set_row(struct udevice *dev, uint row, int clr)
 	default:
 		return -ENOSYS;
 	}
-	ret = vidconsole_sync_copy(dev, line, end);
-	if (ret)
-		return ret;
 
 	video_damage(dev->parent, 0, vc_priv->y_charsize * row, vid_priv->xsize,
 		     vc_priv->y_charsize);
@@ -204,14 +201,11 @@ static int console_truetype_move_rows(struct udevice *dev, uint rowdst,
 	struct console_tt_metrics *met = priv->cur_met;
 	void *dst;
 	void *src;
-	int i, diff, ret;
+	int i, diff;
 
 	dst = vid_priv->fb + rowdst * met->font_size * vid_priv->line_length;
 	src = vid_priv->fb + rowsrc * met->font_size * vid_priv->line_length;
-	ret = vidconsole_memmove(dev, dst, src, met->font_size *
-				 vid_priv->line_length * count);
-	if (ret)
-		return ret;
+	memmove(dev, dst, src, met->font_size * vid_priv->line_length * count);
 
 	/* Scroll up our position history */
 	diff = (rowsrc - rowdst) * met->font_size;
@@ -382,9 +376,6 @@ static int console_truetype_putc_xy(struct udevice *dev, uint x, uint y,
 	video_damage(dev->parent, VID_TO_PIXEL(x) + xoff,
 		     y + priv->baseline + yoff, width, height);
 
-	ret = vidconsole_sync_copy(dev, start, line);
-	if (ret)
-		return ret;
 	free(data);
 
 	return width_frac;
@@ -452,10 +443,6 @@ static int console_truetype_erase(struct udevice *dev, int xstart, int ystart,
 
 	video_damage(dev->parent, xstart, ystart, xend - xstart, yend - ystart);
 
-	ret = vidconsole_sync_copy(dev, start, line);
-	if (ret)
-		return ret;
-
 	return 0;
 }
 
diff --git a/drivers/video/vidconsole-uclass.c b/drivers/video/vidconsole-uclass.c
index 6bdfb6e37d..c6447baf36 100644
--- a/drivers/video/vidconsole-uclass.c
+++ b/drivers/video/vidconsole-uclass.c
@@ -601,22 +601,6 @@ UCLASS_DRIVER(vidconsole) = {
 	.per_device_auto	= sizeof(struct vidconsole_priv),
 };
 
-#ifdef CONFIG_VIDEO_COPY
-int vidconsole_sync_copy(struct udevice *dev, void *from, void *to)
-{
-	struct udevice *vid = dev_get_parent(dev);
-
-	return video_sync_copy(vid, from, to);
-}
-
-int vidconsole_memmove(struct udevice *dev, void *dst, const void *src,
-		       int size)
-{
-	memmove(dst, src, size);
-	return vidconsole_sync_copy(dev, dst, dst + size);
-}
-#endif
-
 void vidconsole_position_cursor(struct udevice *dev, unsigned col, unsigned row)
 {
 	struct vidconsole_priv *priv = dev_get_uclass_priv(dev);
diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index bf93f524c7..73601712ef 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -131,7 +131,6 @@ int video_reserve(ulong *addrp)
 int video_fill(struct udevice *dev, u32 colour)
 {
 	struct video_priv *priv = dev_get_uclass_priv(dev);
-	int ret;
 
 	switch (priv->bpix) {
 	case VIDEO_BPP16:
@@ -156,9 +155,6 @@ int video_fill(struct udevice *dev, u32 colour)
 		memset(priv->fb, colour, priv->fb_size);
 		break;
 	}
-	ret = video_sync_copy(dev, priv->fb, priv->fb + priv->fb_size);
-	if (ret)
-		return ret;
 
 	video_damage(dev, 0, 0, priv->xsize, priv->ysize);
 
@@ -332,6 +328,27 @@ static void video_flush_dcache(struct udevice *vid)
 }
 #endif
 
+static void video_flush_copy(struct udevice *vid)
+{
+	struct video_priv *priv = dev_get_uclass_priv(vid);
+
+	if (!priv->copy_fb)
+		return;
+
+	if (priv->damage.endx && priv->damage.endy) {
+		int lstart = priv->damage.x * VNBYTES(priv->bpix);
+		int lend = priv->damage.endx * VNBYTES(priv->bpix);
+		int y;
+
+		for (y = priv->damage.y; y < priv->damage.endy; y++) {
+			ulong offset = (y * priv->line_length) + lstart;
+			ulong len = lend - lstart;
+
+			memcpy(priv->copy_fb + offset, priv->fb + offset, len);
+		}
+	}
+}
+
 /* Flush video activity to the caches */
 int video_sync(struct udevice *vid, bool force)
 {
@@ -339,6 +356,9 @@ int video_sync(struct udevice *vid, bool force)
 	struct video_ops *ops = video_get_ops(vid);
 	int ret;
 
+	if (CONFIG_IS_ENABLED(VIDEO_COPY))
+		video_flush_copy(vid);
+
 	if (ops && ops->video_sync) {
 		ret = ops->video_sync(vid);
 		if (ret)
@@ -413,69 +433,6 @@ int video_get_ysize(struct udevice *dev)
 	return priv->ysize;
 }
 
-#ifdef CONFIG_VIDEO_COPY
-int video_sync_copy(struct udevice *dev, void *from, void *to)
-{
-	struct video_priv *priv = dev_get_uclass_priv(dev);
-
-	if (priv->copy_fb) {
-		long offset, size;
-
-		/* Find the offset of the first byte to copy */
-		if ((ulong)to > (ulong)from) {
-			size = to - from;
-			offset = from - priv->fb;
-		} else {
-			size = from - to;
-			offset = to - priv->fb;
-		}
-
-		/*
-		 * Allow a bit of leeway for valid requests somewhere near the
-		 * frame buffer
-		 */
-		if (offset < -priv->fb_size || offset > 2 * priv->fb_size) {
-#ifdef DEBUG
-			char str[120];
-
-			snprintf(str, sizeof(str),
-				 "[** FAULT sync_copy fb=%p, from=%p, to=%p, offset=%lx]",
-				 priv->fb, from, to, offset);
-			console_puts_select_stderr(true, str);
-#endif
-			return -EFAULT;
-		}
-
-		/*
-		 * Silently crop the memcpy. This allows callers to avoid doing
-		 * this themselves. It is common for the end pointer to go a
-		 * few lines after the end of the frame buffer, since most of
-		 * the update algorithms terminate a line after their last write
-		 */
-		if (offset + size > priv->fb_size) {
-			size = priv->fb_size - offset;
-		} else if (offset < 0) {
-			size += offset;
-			offset = 0;
-		}
-
-		memcpy(priv->copy_fb + offset, priv->fb + offset, size);
-	}
-
-	return 0;
-}
-
-int video_sync_copy_all(struct udevice *dev)
-{
-	struct video_priv *priv = dev_get_uclass_priv(dev);
-
-	video_sync_copy(dev, priv->fb, priv->fb + priv->fb_size);
-
-	return 0;
-}
-
-#endif
-
 #define SPLASH_DECL(_name) \
 	extern u8 __splash_ ## _name ## _begin[]; \
 	extern u8 __splash_ ## _name ## _end[]
diff --git a/drivers/video/video_bmp.c b/drivers/video/video_bmp.c
index 7dc5b011a8..609dc9fef6 100644
--- a/drivers/video/video_bmp.c
+++ b/drivers/video/video_bmp.c
@@ -254,7 +254,6 @@ int video_bmp_display(struct udevice *dev, ulong bmp_image, int x, int y,
 	enum video_format eformat;
 	struct bmp_color_table_entry *palette;
 	int hdr_size;
-	int ret;
 
 	if (!bmp || !(bmp->header.signature[0] == 'B' &&
 	    bmp->header.signature[1] == 'M')) {
@@ -426,11 +425,5 @@ int video_bmp_display(struct udevice *dev, ulong bmp_image, int x, int y,
 
 	video_damage(dev, x, y, width, height);
 
-	/* Find the position of the top left of the image in the framebuffer */
-	fb = (uchar *)(priv->fb + y * priv->line_length + x * bpix / 8);
-	ret = video_sync_copy(dev, start, fb);
-	if (ret)
-		return log_ret(ret);
-
 	return video_sync(dev, false);
 }
diff --git a/include/video.h b/include/video.h
index 4b35e97f79..e1162fc533 100644
--- a/include/video.h
+++ b/include/video.h
@@ -302,43 +302,6 @@ void video_set_default_colors(struct udevice *dev, bool invert);
  */
 int video_default_font_height(struct udevice *dev);
 
-#ifdef CONFIG_VIDEO_COPY
-/**
- * vidconsole_sync_copy() - Sync back to the copy framebuffer
- *
- * This ensures that the copy framebuffer has the same data as the framebuffer
- * for a particular region. It should be called after the framebuffer is updated
- *
- * @from and @to can be in either order. The region between them is synced.
- *
- * @dev: Vidconsole device being updated
- * @from: Start/end address within the framebuffer (->fb)
- * @to: Other address within the frame buffer
- * Return: 0 if OK, -EFAULT if the start address is before the start of the
- *	frame buffer start
- */
-int video_sync_copy(struct udevice *dev, void *from, void *to);
-
-/**
- * video_sync_copy_all() - Sync the entire framebuffer to the copy
- *
- * @dev: Vidconsole device being updated
- * Return: 0 (always)
- */
-int video_sync_copy_all(struct udevice *dev);
-#else
-static inline int video_sync_copy(struct udevice *dev, void *from, void *to)
-{
-	return 0;
-}
-
-static inline int video_sync_copy_all(struct udevice *dev)
-{
-	return 0;
-}
-
-#endif
-
 /**
  * video_damage() - Notify the video subsystem about screen updates.
  *
diff --git a/include/video_console.h b/include/video_console.h
index d755eb73cf..10d2d111c2 100644
--- a/include/video_console.h
+++ b/include/video_console.h
@@ -256,53 +256,4 @@ int vidconsole_select_font(struct udevice *dev, const char *name, uint size);
  */
 const char *vidconsole_get_font(struct udevice *dev, uint *sizep);
 
-#ifdef CONFIG_VIDEO_COPY
-/**
- * vidconsole_sync_copy() - Sync back to the copy framebuffer
- *
- * This ensures that the copy framebuffer has the same data as the framebuffer
- * for a particular region. It should be called after the framebuffer is updated
- *
- * @from and @to can be in either order. The region between them is synced.
- *
- * @dev: Vidconsole device being updated
- * @from: Start/end address within the framebuffer (->fb)
- * @to: Other address within the frame buffer
- * Return: 0 if OK, -EFAULT if the start address is before the start of the
- *	frame buffer start
- */
-int vidconsole_sync_copy(struct udevice *dev, void *from, void *to);
-
-/**
- * vidconsole_memmove() - Perform a memmove() within the frame buffer
- *
- * This handles a memmove(), e.g. for scrolling. It also updates the copy
- * framebuffer.
- *
- * @dev: Vidconsole device being updated
- * @dst: Destination address within the framebuffer (->fb)
- * @src: Source address within the framebuffer (->fb)
- * @size: Number of bytes to transfer
- * Return: 0 if OK, -EFAULT if the start address is before the start of the
- *	frame buffer start
- */
-int vidconsole_memmove(struct udevice *dev, void *dst, const void *src,
-		       int size);
-#else
-static inline int vidconsole_sync_copy(struct udevice *dev, void *from,
-				       void *to)
-{
-	return 0;
-}
-
-static inline int vidconsole_memmove(struct udevice *dev, void *dst,
-				     const void *src, int size)
-{
-	memmove(dst, src, size);
-
-	return 0;
-}
-
-#endif
-
 #endif
-- 
2.37.1 (Apple Git-137.1)

Re: [PATCH v3 5/7] efi_loader: GOP: Add damage notification on BLT

[Heinrich Schuchardt]

On 12/30/22 20:58, Alexander Graf wrote:
> Now that we have a damage tracking API, let's populate damage done by
> UEFI payloads when they BLT data onto the screen.
>
> Signed-off-by: Alexander Graf <agraf@csgraf.de>
> Reported-by: Da Xue <da@libre.computer>
>
> ---
>
> v1 -> v2:
>
>    - Remove ifdefs from gop
>
> v2 -> v3:
>
>    - Adapt to always assume DM is used
> ---
>   lib/efi_loader/efi_gop.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/lib/efi_loader/efi_gop.c b/lib/efi_loader/efi_gop.c
> index d1dc2f22d0..c80d307cbf 100644
> --- a/lib/efi_loader/efi_gop.c
> +++ b/lib/efi_loader/efi_gop.c
> @@ -32,6 +32,7 @@ struct efi_gop_obj {
>   	struct efi_gop ops;
>   	struct efi_gop_mode_info info;
>   	struct efi_gop_mode mode;
> +	struct udevice *vdev;
>   	/* Fields we only have access to during init */
>   	u32 bpix;
>   	void *fb;
> @@ -243,6 +244,8 @@ static __always_inline efi_status_t gop_blt_int(struct efi_gop *this,
>   		dlineoff += dwidth;
>   	}
>

Hello Alexander,

Please, do not call video_damage() for EfiBltVideoToBltBuffer. Otherwise
looks good to me.

You somehow missed to CC Ilias, cf. scripts/get_maintainer.pl.

Best regards

Heinrich

> +	video_damage(gopobj->vdev, dx, dy, width, height);
> +
>   	return EFI_SUCCESS;
>   }
>
> @@ -547,6 +550,7 @@ efi_status_t efi_gop_register(void)
>   	gopobj->info.pixels_per_scanline = col;
>   	gopobj->bpix = bpix;
>   	gopobj->fb = fb;
> +	gopobj->vdev = vdev;
>
>   	return EFI_SUCCESS;
>   }

Re: [PATCH v3 6/7] video: Only dcache flush damaged lines

[Heinrich Schuchardt]

On 12/30/22 20:58, Alexander Graf wrote:
> Now that we have a damage area tells us which parts of the frame buffer
> actually need updating, let's only dcache flush those on video_sync()
> calls. With this optimization in place, frame buffer updates - especially
> on large screen such as 4k displays - speed up significantly.
>
> Signed-off-by: Alexander Graf <agraf@csgraf.de>
> Reported-by: Da Xue <da@libre.computer>
>
> ---
>
> v1 -> v2:
>
>    - Fix dcache range; we were flushing too much before
>    - Remove ifdefs
> ---
>   drivers/video/video-uclass.c | 51 ++++++++++++++++++++++++++++++------
>   1 file changed, 43 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
> index f1fbeaadcb..bf93f524c7 100644
> --- a/drivers/video/video-uclass.c
> +++ b/drivers/video/video-uclass.c
> @@ -297,9 +297,45 @@ int video_damage(struct udevice *vid, int x, int y, int width, int height)
>   	return 0;
>   }
>
> +#if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
> +static void video_flush_dcache(struct udevice *vid)
> +{
> +	struct video_priv *priv = dev_get_uclass_priv(vid);
> +
> +	if (!priv->flush_dcache)
> +		return;
> +
> +	if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
> +		flush_dcache_range((ulong)priv->fb,
> +				   ALIGN((ulong)priv->fb + priv->fb_size,
> +					 CONFIG_SYS_CACHELINE_SIZE));
> +
> +		return;
> +	}
> +
> +	if (priv->damage.endx && priv->damage.endy) {
> +		int lstart = priv->damage.x * VNBYTES(priv->bpix);
> +		int lend = priv->damage.endx * VNBYTES(priv->bpix);
> +		int y;
> +
> +		for (y = priv->damage.y; y < priv->damage.endy; y++) {
> +			ulong fb = (ulong)priv->fb;
> +			ulong start = fb + (y * priv->line_length) + lstart;
> +			ulong end = start + lend - lstart;
> +
> +			start = ALIGN_DOWN(start, CONFIG_SYS_CACHELINE_SIZE);
> +			end = ALIGN(end, CONFIG_SYS_CACHELINE_SIZE);
> +
> +			flush_dcache_range(start, end);
> +		}
> +	}
> +}
> +#endif
> +
>   /* Flush video activity to the caches */
>   int video_sync(struct udevice *vid, bool force)
>   {
> +	struct video_priv *priv = dev_get_uclass_priv(vid);
>   	struct video_ops *ops = video_get_ops(vid);
>   	int ret;
>
> @@ -315,15 +351,8 @@ int video_sync(struct udevice *vid, bool force)
>   	 * out whether it exists? For now, ARM is safe.
>   	 */
>   #if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
> -	struct video_priv *priv = dev_get_uclass_priv(vid);
> -
> -	if (priv->flush_dcache) {
> -		flush_dcache_range((ulong)priv->fb,
> -				   ALIGN((ulong)priv->fb + priv->fb_size,
> -					 CONFIG_SYS_CACHELINE_SIZE));
> -	}
> +	video_flush_dcache(vid);
>   #elif defined(CONFIG_VIDEO_SANDBOX_SDL)
> -	struct video_priv *priv = dev_get_uclass_priv(vid);
>   	static ulong last_sync;
>
>   	if (force || get_timer(last_sync) > 100) {
> @@ -331,6 +360,12 @@ int video_sync(struct udevice *vid, bool force)
>   		last_sync = get_timer(0);
>   	}
>   #endif
> +
> +	if (CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
> +		priv->damage.endx = 0;
> +		priv->damage.endy = 0;

priv->damage.x = priv->xsize;
priv->damage.y = priv->ysize;

With this you can avoid differentiating between first damage and later
damage in video_damage().

Best regards

Heinrich

> +	}
> +
>   	return 0;
>   }
>

Re: [PATCH v3 1/7] dm: video: Add damage tracking API

[Heinrich Schuchardt]

On 12/30/22 20:58, Alexander Graf wrote:
> 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>
>
> ---
>
> v1 -> v2:
>
>    - Remove ifdefs
>
> v2 -> v3:
>
>    - Adapt Kconfig to DM always
> ---
>   drivers/video/Kconfig        | 14 ++++++++++++
>   drivers/video/video-uclass.c | 41 ++++++++++++++++++++++++++++++++++++
>   include/video.h              | 29 +++++++++++++++++++++++--
>   3 files changed, 82 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index f539977d9b..e12457c654 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -62,6 +62,20 @@ config VIDEO_COPY
>   	  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"
> +	default y if ARM && !SYS_DCACHE_OFF
> +	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 0ce376ca3f..48a053841e 100644
> --- a/drivers/video/video-uclass.c
> +++ b/drivers/video/video-uclass.c
> @@ -21,6 +21,8 @@
>   #include <dm/device_compat.h>
>   #include <dm/device-internal.h>
>   #include <dm/uclass-internal.h>
> +#include <linux/types.h>
> +#include <linux/bitmap.h>
>   #ifdef CONFIG_SANDBOX
>   #include <asm/sdl.h>
>   #endif
> @@ -254,6 +256,45 @@ void video_set_default_colors(struct udevice *dev, bool invert)
>   	priv->colour_bg = video_index_to_colour(priv, back);
>   }
>
> +/* Notify about changes in the frame buffer */
> +int video_damage(struct udevice *vid, int x, int y, int width, int height)
> +{
> +	struct video_priv *priv = dev_get_uclass_priv(vid);
> +	int endx = x + width;
> +	int endy = y + height;
> +
> +	if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE))
> +		return 0;
> +
> +	if (x > priv->xsize)
> +		return 0;
> +
> +	if (y > priv->ysize)
> +		return 0;
> +
> +	if (endx > priv->xsize)
> +		endx = priv->xsize;
> +
> +	if (endy > priv->ysize)
> +		endy = priv->ysize;
> +
> +	if (priv->damage.endx && priv->damage.endy) {

This if is superfluous if you initialize x = priv->xsize, y =
priv->ysize in video_flush_dcache().

Please, simplify the code.

Best regards

Heinrich

> +		/* Span a rectangle across all old and new damage */
> +		priv->damage.x = min(x, priv->damage.x);
> +		priv->damage.y = min(y, priv->damage.y);
> +		priv->damage.endx = max(endx, priv->damage.endx);
> +		priv->damage.endy = max(endy, priv->damage.endy);
> +	} else {
> +		/* First damage, setting the rectangle to span it */
> +		priv->damage.x = x;
> +		priv->damage.y = y;
> +		priv->damage.endx = endx;
> +		priv->damage.endy = endy;
> +	}
> +
> +	return 0;
> +}
> +
>   /* Flush video activity to the caches */
>   int video_sync(struct udevice *vid, bool force)
>   {
> diff --git a/include/video.h b/include/video.h
> index 43f2e2c02f..4b35e97f79 100644
> --- a/include/video.h
> +++ b/include/video.h
> @@ -109,6 +109,12 @@ struct video_priv {
>   	void *fb;
>   	int fb_size;
>   	void *copy_fb;
> +	struct {
> +		int x;
> +		int y;
> +		int endx;
> +		int endy;
> +	} damage;
>   	int line_length;
>   	u32 colour_fg;
>   	u32 colour_bg;
> @@ -211,8 +217,9 @@ int video_fill(struct udevice *dev, u32 colour);
>    * @return: 0 on success, error code otherwise
>    *
>    * Some frame buffers are cached or have a secondary frame buffer. This
> - * function syncs these up so that the current contents of the U-Boot frame
> - * buffer are displayed to the user.
> + * function syncs the damaged parts of them up so that the current contents
> + * of the U-Boot frame buffer are displayed to the user. It clears the damage
> + * buffer.
>    */
>   int video_sync(struct udevice *vid, bool force);
>
> @@ -332,6 +339,24 @@ static inline int video_sync_copy_all(struct udevice *dev)
>
>   #endif
>
> +/**
> + * video_damage() - Notify the video subsystem about screen updates.
> + *
> + * @vid:	Device to sync
> + * @x:	        Upper left X coordinate of the damaged rectangle
> + * @y:	        Upper left Y coordinate of the damaged rectangle
> + * @width:	Width of the damaged rectangle
> + * @height:	Height of the damaged rectangle
> + *
> + * @return: 0
> + *
> + * Some frame buffers are cached or have a secondary frame buffer. This
> + * function notifies the video subsystem about rectangles that were updated
> + * within the frame buffer. They may only get written to the screen on the
> + * next call to video_sync().
> + */
> +int video_damage(struct udevice *vid, int x, int y, int width, int height);
> +
>   /**
>    * video_is_active() - Test if one video device it active
>    *

Re: [PATCH v3 6/7] video: Only dcache flush damaged lines

[Heinrich Schuchardt]

On 12/30/22 20:58, Alexander Graf wrote:
> Now that we have a damage area tells us which parts of the frame buffer
> actually need updating, let's only dcache flush those on video_sync()
> calls. With this optimization in place, frame buffer updates - especially
> on large screen such as 4k displays - speed up significantly.
>
> Signed-off-by: Alexander Graf <agraf@csgraf.de>
> Reported-by: Da Xue <da@libre.computer>
>
> ---
>
> v1 -> v2:
>
>    - Fix dcache range; we were flushing too much before
>    - Remove ifdefs
> ---
>   drivers/video/video-uclass.c | 51 ++++++++++++++++++++++++++++++------
>   1 file changed, 43 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
> index f1fbeaadcb..bf93f524c7 100644
> --- a/drivers/video/video-uclass.c
> +++ b/drivers/video/video-uclass.c
> @@ -297,9 +297,45 @@ int video_damage(struct udevice *vid, int x, int y, int width, int height)
>   	return 0;
>   }
>
> +#if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)

ARM isn't the only architecture implementing flush_dcache_range().
So this condition needs to be fixed as well as the one in video_sync.

Why don't you simply rely on priv->flash_dcache irrespective of the
architecture? Let the video drivers decide if they need it.

Best regards

Heinrich

> +static void video_flush_dcache(struct udevice *vid)
> +{
> +	struct video_priv *priv = dev_get_uclass_priv(vid);
> +
> +	if (!priv->flush_dcache)
> +		return;
> +
> +	if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
> +		flush_dcache_range((ulong)priv->fb,
> +				   ALIGN((ulong)priv->fb + priv->fb_size,
> +					 CONFIG_SYS_CACHELINE_SIZE));
> +
> +		return;
> +	}
> +
> +	if (priv->damage.endx && priv->damage.endy) {
> +		int lstart = priv->damage.x * VNBYTES(priv->bpix);
> +		int lend = priv->damage.endx * VNBYTES(priv->bpix);
> +		int y;
> +
> +		for (y = priv->damage.y; y < priv->damage.endy; y++) {
> +			ulong fb = (ulong)priv->fb;
> +			ulong start = fb + (y * priv->line_length) + lstart;
> +			ulong end = start + lend - lstart;
> +
> +			start = ALIGN_DOWN(start, CONFIG_SYS_CACHELINE_SIZE);
> +			end = ALIGN(end, CONFIG_SYS_CACHELINE_SIZE);
> +
> +			flush_dcache_range(start, end);
> +		}
> +	}
> +}
> +#endif
> +
>   /* Flush video activity to the caches */
>   int video_sync(struct udevice *vid, bool force)
>   {
> +	struct video_priv *priv = dev_get_uclass_priv(vid);
>   	struct video_ops *ops = video_get_ops(vid);
>   	int ret;
>
> @@ -315,15 +351,8 @@ int video_sync(struct udevice *vid, bool force)
>   	 * out whether it exists? For now, ARM is safe.
>   	 */
>   #if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
> -	struct video_priv *priv = dev_get_uclass_priv(vid);
> -
> -	if (priv->flush_dcache) {
> -		flush_dcache_range((ulong)priv->fb,
> -				   ALIGN((ulong)priv->fb + priv->fb_size,
> -					 CONFIG_SYS_CACHELINE_SIZE));
> -	}
> +	video_flush_dcache(vid);
>   #elif defined(CONFIG_VIDEO_SANDBOX_SDL)
> -	struct video_priv *priv = dev_get_uclass_priv(vid);
>   	static ulong last_sync;
>
>   	if (force || get_timer(last_sync) > 100) {
> @@ -331,6 +360,12 @@ int video_sync(struct udevice *vid, bool force)
>   		last_sync = get_timer(0);
>   	}
>   #endif
> +
> +	if (CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
> +		priv->damage.endx = 0;
> +		priv->damage.endy = 0;
> +	}
> +
>   	return 0;
>   }
>

Re: [PATCH v3 1/7] dm: video: Add damage tracking API

[Heinrich Schuchardt]

On 12/30/22 20:58, Alexander Graf wrote:
> 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>
>
> ---
>
> v1 -> v2:
>
>    - Remove ifdefs
>
> v2 -> v3:
>
>    - Adapt Kconfig to DM always
> ---
>   drivers/video/Kconfig        | 14 ++++++++++++
>   drivers/video/video-uclass.c | 41 ++++++++++++++++++++++++++++++++++++
>   include/video.h              | 29 +++++++++++++++++++++++--
>   3 files changed, 82 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index f539977d9b..e12457c654 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -62,6 +62,20 @@ config VIDEO_COPY
>   	  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"
> +	default y if ARM && !SYS_DCACHE_OFF

If CONFIG_VIDEO_DAMAGE make sense or not, does not depend on the
architecture but on caching of the video buffer being enabled.

default=y should only be set for those video drivers calling
video_set_flush_dcache(dev, true).

Best regards

Heinrich

> +	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 0ce376ca3f..48a053841e 100644
> --- a/drivers/video/video-uclass.c
> +++ b/drivers/video/video-uclass.c
> @@ -21,6 +21,8 @@
>   #include <dm/device_compat.h>
>   #include <dm/device-internal.h>
>   #include <dm/uclass-internal.h>
> +#include <linux/types.h>
> +#include <linux/bitmap.h>
>   #ifdef CONFIG_SANDBOX
>   #include <asm/sdl.h>
>   #endif
> @@ -254,6 +256,45 @@ void video_set_default_colors(struct udevice *dev, bool invert)
>   	priv->colour_bg = video_index_to_colour(priv, back);
>   }
>
> +/* Notify about changes in the frame buffer */
> +int video_damage(struct udevice *vid, int x, int y, int width, int height)
> +{
> +	struct video_priv *priv = dev_get_uclass_priv(vid);
> +	int endx = x + width;
> +	int endy = y + height;
> +
> +	if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE))
> +		return 0;
> +
> +	if (x > priv->xsize)
> +		return 0;
> +
> +	if (y > priv->ysize)
> +		return 0;
> +
> +	if (endx > priv->xsize)
> +		endx = priv->xsize;
> +
> +	if (endy > priv->ysize)
> +		endy = priv->ysize;
> +
> +	if (priv->damage.endx && priv->damage.endy) {
> +		/* Span a rectangle across all old and new damage */
> +		priv->damage.x = min(x, priv->damage.x);
> +		priv->damage.y = min(y, priv->damage.y);
> +		priv->damage.endx = max(endx, priv->damage.endx);
> +		priv->damage.endy = max(endy, priv->damage.endy);
> +	} else {
> +		/* First damage, setting the rectangle to span it */
> +		priv->damage.x = x;
> +		priv->damage.y = y;
> +		priv->damage.endx = endx;
> +		priv->damage.endy = endy;
> +	}
> +
> +	return 0;
> +}
> +
>   /* Flush video activity to the caches */
>   int video_sync(struct udevice *vid, bool force)
>   {
> diff --git a/include/video.h b/include/video.h
> index 43f2e2c02f..4b35e97f79 100644
> --- a/include/video.h
> +++ b/include/video.h
> @@ -109,6 +109,12 @@ struct video_priv {
>   	void *fb;
>   	int fb_size;
>   	void *copy_fb;
> +	struct {
> +		int x;
> +		int y;
> +		int endx;
> +		int endy;
> +	} damage;
>   	int line_length;
>   	u32 colour_fg;
>   	u32 colour_bg;
> @@ -211,8 +217,9 @@ int video_fill(struct udevice *dev, u32 colour);
>    * @return: 0 on success, error code otherwise
>    *
>    * Some frame buffers are cached or have a secondary frame buffer. This
> - * function syncs these up so that the current contents of the U-Boot frame
> - * buffer are displayed to the user.
> + * function syncs the damaged parts of them up so that the current contents
> + * of the U-Boot frame buffer are displayed to the user. It clears the damage
> + * buffer.
>    */
>   int video_sync(struct udevice *vid, bool force);
>
> @@ -332,6 +339,24 @@ static inline int video_sync_copy_all(struct udevice *dev)
>
>   #endif
>
> +/**
> + * video_damage() - Notify the video subsystem about screen updates.
> + *
> + * @vid:	Device to sync
> + * @x:	        Upper left X coordinate of the damaged rectangle
> + * @y:	        Upper left Y coordinate of the damaged rectangle
> + * @width:	Width of the damaged rectangle
> + * @height:	Height of the damaged rectangle
> + *
> + * @return: 0
> + *
> + * Some frame buffers are cached or have a secondary frame buffer. This
> + * function notifies the video subsystem about rectangles that were updated
> + * within the frame buffer. They may only get written to the screen on the
> + * next call to video_sync().
> + */
> +int video_damage(struct udevice *vid, int x, int y, int width, int height);
> +
>   /**
>    * video_is_active() - Test if one video device it active
>    *

Re: [PATCH v3 6/7] video: Only dcache flush damaged lines

[Alexander Graf]

On 30.12.22 22:12, Heinrich Schuchardt wrote:
> On 12/30/22 20:58, Alexander Graf wrote:
>> Now that we have a damage area tells us which parts of the frame buffer
>> actually need updating, let's only dcache flush those on video_sync()
>> calls. With this optimization in place, frame buffer updates - 
>> especially
>> on large screen such as 4k displays - speed up significantly.
>>
>> Signed-off-by: Alexander Graf <agraf@csgraf.de>
>> Reported-by: Da Xue <da@libre.computer>
>>
>> ---
>>
>> v1 -> v2:
>>
>>    - Fix dcache range; we were flushing too much before
>>    - Remove ifdefs
>> ---
>>   drivers/video/video-uclass.c | 51 ++++++++++++++++++++++++++++++------
>>   1 file changed, 43 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
>> index f1fbeaadcb..bf93f524c7 100644
>> --- a/drivers/video/video-uclass.c
>> +++ b/drivers/video/video-uclass.c
>> @@ -297,9 +297,45 @@ int video_damage(struct udevice *vid, int x, int 
>> y, int width, int height)
>>       return 0;
>>   }
>>
>> +#if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
>
> ARM isn't the only architecture implementing flush_dcache_range().
> So this condition needs to be fixed as well as the one in video_sync.
>
> Why don't you simply rely on priv->flash_dcache irrespective of the
> architecture? Let the video drivers decide if they need it.


This is code that already was #ifdef'ed before. The way I understand its 
history, we couldn't decisively ensure that flush_dcache_range() exists, 
so we couldn't build the code always.

I agree that it looks weird and error prone though. I believe you're 
trying to say we should just make sure there's always a 
flush_dcache_range() function and keep the rest to the compiler?



Alex

Re: [PATCH v3 6/7] video: Only dcache flush damaged lines

[Simon Glass]

Hi,

On Tue, 3 Jan 2023 at 13:25, Alexander Graf <agraf@csgraf.de> wrote:
>
>
> On 30.12.22 22:12, Heinrich Schuchardt wrote:
> > On 12/30/22 20:58, Alexander Graf wrote:
> >> Now that we have a damage area tells us which parts of the frame buffer
> >> actually need updating, let's only dcache flush those on video_sync()
> >> calls. With this optimization in place, frame buffer updates -
> >> especially
> >> on large screen such as 4k displays - speed up significantly.
> >>
> >> Signed-off-by: Alexander Graf <agraf@csgraf.de>
> >> Reported-by: Da Xue <da@libre.computer>
> >>
> >> ---
> >>
> >> v1 -> v2:
> >>
> >>    - Fix dcache range; we were flushing too much before
> >>    - Remove ifdefs
> >> ---
> >>   drivers/video/video-uclass.c | 51 ++++++++++++++++++++++++++++++------
> >>   1 file changed, 43 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
> >> index f1fbeaadcb..bf93f524c7 100644
> >> --- a/drivers/video/video-uclass.c
> >> +++ b/drivers/video/video-uclass.c
> >> @@ -297,9 +297,45 @@ int video_damage(struct udevice *vid, int x, int
> >> y, int width, int height)
> >>       return 0;
> >>   }
> >>
> >> +#if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
> >
> > ARM isn't the only architecture implementing flush_dcache_range().
> > So this condition needs to be fixed as well as the one in video_sync.
> >
> > Why don't you simply rely on priv->flash_dcache irrespective of the
> > architecture? Let the video drivers decide if they need it.
>
>
> This is code that already was #ifdef'ed before. The way I understand its
> history, we couldn't decisively ensure that flush_dcache_range() exists,
> so we couldn't build the code always.
>
> I agree that it looks weird and error prone though. I believe you're
> trying to say we should just make sure there's always a
> flush_dcache_range() function and keep the rest to the compiler?
>
Can  / should we use the dma_map stuff here?

Regards,
Simon