[PATCH v3 0/5] video: Improve syncing performance with cyclic

[PATCH v3 0/5] video: Improve syncing performance with cyclic

[Simon Glass]

Now that U-Boot has a background-processing feature, it is possible to
reduce the amount of 'foreground' syncing of the display. At present
this happens quite often.

Foreground syncing blocks all other processing, sometimes for 10ms or
more. When pasting commands into U-Boot over the UART, this typically
result in characters being dropped. For example, on rpi_4 it isn't
possible to paste in more than 35 characters before things fail. This
makes updating the environment or entering long commands very painful
over the console, since text must be pasted in chunks, or the
vidconsole device must be dropped from stdout.

This series introduces background syncing, enabled by default for
boards which use video. The sync rates for foreground and background
are configurable.

With this series it is possible to paste in any amount of text to the
command line. Some sandbox-specific workarounds can now be removed and
sandbox video (./u-boot -Dl) is significantly more responsive.

This obviously increases code size, since it enables a subsystem not
normally used by default. However it only applies to boards which have
VIDEO enabled, which are presumably less worried about memory space
since the video code is fairly large.

Also it is possible to disable CMD_CYCLIC and reduce the growth to:

   aarch64: (for 1/1 boards) all +1081.0 rodata +65.0 text +1016.0
       arm: (for 1/1 boards) all +945.0 rodata +65.0 text +880.0

Without that, the increase doubles.

It is of course possible to disable CYCLIC and still use VIDEO but this
reverts to the current behaviour

Changes in v3:
- Drop inclusion of kconfig.h in cyclic.h
- Adapt to new cyclic API

Changes in v2:
- Add an SPL_CYCLIC symbol
- Add a lot more explanation about the header files
- Expand help for CONFIG_VIDEO
- Fix 'groth' and 'work-around' typos in cover letter

Simon Glass (5):
  cyclic: Add a symbol for SPL
  video: Move last_sync to private data
  video: Use cyclic to handle video sync
  sandbox: Increase cyclic CPU-time limit
  sandbox: Drop video-sync in serial driver

 common/Kconfig                    |  9 ++++++
 common/Makefile                   |  2 +-
 drivers/serial/sandbox.c          |  2 --
 drivers/video/Kconfig             | 35 +++++++++++++++++++++
 drivers/video/video-uclass.c      | 52 +++++++++++++++++++++++++------
 drivers/watchdog/Kconfig          |  1 +
 include/asm-generic/global_data.h |  2 +-
 include/cyclic.h                  |  5 +--
 include/video.h                   |  2 ++
 9 files changed, 95 insertions(+), 15 deletions(-)

-- 
2.34.1

[PATCH v3 1/5] cyclic: Add a symbol for SPL

[Simon Glass]

The cyclic subsystem is currently enabled either in all build phases
or none. For tools this should not be enabled, but since lib/shc256.c
and other files include watchdog.h in the host build, we must make
sure that it is not enabled there.

Add an SPL symbol so that there is more control of this.

Add an include into cyclic.h so that tools can include this file.

Also add the kconfig.h header so that CONFIG_IS_ENABLED() works. We
could avoid this for now by moving the location of the watchdog.h
inclusion to outside the USE_HOSTCC area. But at some point the #ifdefs
from these files will likely be removed, so there is no benefit in
going that way.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Reviewed-by: Stefan Roese <sr@denx.de>
---

Changes in v3:
- Drop inclusion of kconfig.h in cyclic.h

Changes in v2:
- Add an SPL_CYCLIC symbol
- Add a lot more explanation about the header files

 common/Kconfig                    | 8 ++++++++
 common/Makefile                   | 2 +-
 drivers/watchdog/Kconfig          | 1 +
 include/asm-generic/global_data.h | 2 +-
 include/cyclic.h                  | 5 +++--
 5 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/common/Kconfig b/common/Kconfig
index 4bb9f08977a..87b0ec3ea8f 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -626,6 +626,14 @@ config CYCLIC
 
 if CYCLIC
 
+config SPL_CYCLIC
+	bool "General-purpose cyclic execution mechanism (SPL)"
+	help
+	  This enables a general-purpose cyclic execution infrastructure in SPL,
+	  to allow "small" (run-time wise) functions to be executed at
+	  a specified frequency. Things like LED blinking or watchdog
+	  triggering are examples for such tasks.
+
 config CYCLIC_MAX_CPU_TIME_US
 	int "Sets the max allowed time for a cyclic function in us"
 	default 5000
diff --git a/common/Makefile b/common/Makefile
index e9835473420..d871113cbb9 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -79,7 +79,7 @@ obj-$(CONFIG_CROS_EC) += cros_ec.o
 obj-y += dlmalloc.o
 obj-$(CONFIG_$(SPL_TPL_)SYS_MALLOC_F) += malloc_simple.o
 
-obj-$(CONFIG_CYCLIC) += cyclic.o
+obj-$(CONFIG_$(SPL_TPL_)CYCLIC) += cyclic.o
 obj-$(CONFIG_$(SPL_TPL_)EVENT) += event.o
 
 obj-$(CONFIG_$(SPL_TPL_)HASH) += hash.o
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 8318fd77a32..05de46db024 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -408,6 +408,7 @@ config WDT_ARM_SMC
 config SPL_WDT
 	bool "Enable driver model for watchdog timer drivers in SPL"
 	depends on SPL_DM
+	select SPL_CYCLIC if CYCLIC
 	help
 	  Enable driver model for watchdog timer in SPL.
 	  This is similar to CONFIG_WDT in U-Boot.
diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index fcc3c6e14ca..21fb94f95f8 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -485,7 +485,7 @@ struct global_data {
 	 */
 	struct event_state event_state;
 #endif
-#ifdef CONFIG_CYCLIC
+#if CONFIG_IS_ENABLED(CYCLIC)
 	/**
 	 * @cyclic_list: list of registered cyclic functions
 	 */
diff --git a/include/cyclic.h b/include/cyclic.h
index 2c3d383c5ef..cd95b691d48 100644
--- a/include/cyclic.h
+++ b/include/cyclic.h
@@ -46,7 +46,8 @@ struct cyclic_info {
 /** Function type for cyclic functions */
 typedef void (*cyclic_func_t)(struct cyclic_info *c);
 
-#if defined(CONFIG_CYCLIC)
+#if CONFIG_IS_ENABLED(CYCLIC)
+
 /**
  * cyclic_register - Register a new cyclic function
  *
@@ -123,6 +124,6 @@ static inline int cyclic_unregister_all(void)
 {
 	return 0;
 }
-#endif
+#endif /* CYCLIC */
 
 #endif
-- 
2.34.1

[PATCH v3 2/5] video: Move last_sync to private data

[Simon Glass]

Rather than using a static variable, use the video device's private
data to remember when the last video sync was completed. This allows
each display to have its own sync and avoids using static data in SPL.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

(no changes since v1)

 drivers/video/video-uclass.c | 10 +++-------
 include/video.h              |  2 ++
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index ff1382f4a43..a95b5f199dc 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -349,6 +349,7 @@ void video_set_default_colors(struct udevice *dev, bool invert)
 /* 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;
 
@@ -364,20 +365,15 @@ 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));
 	}
 #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) {
+	if (force || get_timer(priv->last_sync) > 100) {
 		sandbox_sdl_sync(priv->fb);
-		last_sync = get_timer(0);
+		priv->last_sync = get_timer(0);
 	}
 #endif
 	return 0;
diff --git a/include/video.h b/include/video.h
index 4d8df9baaad..4013a949983 100644
--- a/include/video.h
+++ b/include/video.h
@@ -97,6 +97,7 @@ enum video_format {
  *		the LCD is updated
  * @fg_col_idx:	Foreground color code (bit 3 = bold, bit 0-2 = color)
  * @bg_col_idx:	Background color code (bit 3 = bold, bit 0-2 = color)
+ * @last_sync:	Monotonic time of last video sync
  */
 struct video_priv {
 	/* Things set up by the driver: */
@@ -121,6 +122,7 @@ struct video_priv {
 	bool flush_dcache;
 	u8 fg_col_idx;
 	u8 bg_col_idx;
+	ulong last_sync;
 };
 
 /**
-- 
2.34.1

[PATCH v3 3/5] video: Use cyclic to handle video sync

[Simon Glass]

At present U-Boot flushes the cache after every character written to
ths display. This makes the command-line slower, to the point that
pasting in long strings can fail.

Add a cyclic function to sync the display every 10ms. Enable this by
default.

Allow much longer times for sandbox, since the SDL display is quite
slow.

Avoid size growth if the feature is disabled by making the new init and
destroy functions dependent on CYCLIC being enabled.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

Changes in v3:
- Adapt to new cyclic API

Changes in v2:
- Expand help for CONFIG_VIDEO

 drivers/video/Kconfig        | 35 +++++++++++++++++++++++++++
 drivers/video/video-uclass.c | 46 ++++++++++++++++++++++++++++++++----
 2 files changed, 77 insertions(+), 4 deletions(-)

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 7808ae7919e..6e79694fd19 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -7,6 +7,7 @@ menu "Graphics support"
 config VIDEO
 	bool "Enable driver model support for LCD/video"
 	depends on DM
+	imply CYCLIC
 	help
 	  This enables driver model for LCD and video devices. These support
 	  a bitmap display of various sizes and depths which can be drawn on
@@ -14,6 +15,11 @@ config VIDEO
 	  option compiles in the video uclass and routes all LCD/video access
 	  through this.
 
+	  If CYCLIC is enabled (which it is by default), the cyclic subsystem
+	  is used to flush pending output to the display periodically, rather
+	  than this happening with every chunk of output. This allows for more
+	  efficient operation and faster display output.
+
 if VIDEO
 
 config VIDEO_FONT_4X6
@@ -232,6 +238,35 @@ config NO_FB_CLEAR
 	  loads takes over the screen.  This, for example, can be used to
 	  keep splash image on screen until grub graphical boot menu starts.
 
+config VIDEO_SYNC_MS
+	int "Video-sync period in milliseconds for foreground processing"
+	default 300 if SANDBOX
+	default 100
+	help
+	  This sets the requested, maximum time before a video sync will take
+	  place, in milliseconds. Note that the time between video syncs
+	  may be longer than this, since syncs only happen when the video system
+	  is used, e.g. by outputting a character to the console.
+
+	  It may also be shorter, since the video uclass will automatically
+	  force a sync in certain situations.
+
+	  Many video-output systems require a sync operation before any output
+	  is visible. This may flush the CPU cache or perhaps copy the
+	  display contents to a hardware framebuffer. Without this, change to
+	  the video may never be displayed.
+
+config VIDEO_SYNC_CYCLIC_MS
+	int "Video-sync period in milliseconds for cyclic processing"
+	depends on CYCLIC
+	default 100 if SANDBOX
+	default 10
+	help
+	  This sets the frequency of cyclic video syncs. The cyclic system is
+	  used to ensure that when U-Boot is idle, it syncs the video. This
+	  improves the responsiveness of the command line to new characters
+	  being entered.
+
 config PANEL
 	bool "Enable panel uclass support"
 	default y
diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index a95b5f199dc..a5aa8dd5295 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -8,6 +8,7 @@
 #include <bloblist.h>
 #include <console.h>
 #include <cpu_func.h>
+#include <cyclic.h>
 #include <dm.h>
 #include <log.h>
 #include <malloc.h>
@@ -52,6 +53,8 @@
  */
 DECLARE_GLOBAL_DATA_PTR;
 
+struct cyclic_info;
+
 /**
  * struct video_uc_priv - Information for the video uclass
  *
@@ -60,9 +63,12 @@ DECLARE_GLOBAL_DATA_PTR;
  *	available address to use for a device's framebuffer. It starts at
  *	gd->video_top and works downwards, running out of space when it hits
  *	gd->video_bottom.
+ * @cyc: handle for cyclic-execution function, or NULL if none
  */
 struct video_uc_priv {
 	ulong video_ptr;
+	bool cyc_active;
+	struct cyclic_info cyc;
 };
 
 /** struct vid_rgb - Describes a video colour */
@@ -359,6 +365,10 @@ int video_sync(struct udevice *vid, bool force)
 			return ret;
 	}
 
+	if (CONFIG_IS_ENABLED(CYCLIC) && !force &&
+	    get_timer(priv->last_sync) < CONFIG_VIDEO_SYNC_MS)
+		return 0;
+
 	/*
 	 * flush_dcache_range() is declared in common.h but it seems that some
 	 * architectures do not actually implement it. Is there a way to find
@@ -371,11 +381,10 @@ int video_sync(struct udevice *vid, bool force)
 					 CONFIG_SYS_CACHELINE_SIZE));
 	}
 #elif defined(CONFIG_VIDEO_SANDBOX_SDL)
-	if (force || get_timer(priv->last_sync) > 100) {
-		sandbox_sdl_sync(priv->fb);
-		priv->last_sync = get_timer(0);
-	}
+	sandbox_sdl_sync(priv->fb);
 #endif
+	priv->last_sync = get_timer(0);
+
 	return 0;
 }
 
@@ -524,10 +533,16 @@ int video_default_font_height(struct udevice *dev)
 	return vc_priv->y_charsize;
 }
 
+static void video_idle(struct cyclic_info *cyc)
+{
+	video_sync_all();
+}
+
 /* Set up the display ready for use */
 static int video_post_probe(struct udevice *dev)
 {
 	struct video_uc_plat *plat = dev_get_uclass_plat(dev);
+	struct video_uc_priv *uc_priv = uclass_get_priv(dev->uclass);
 	struct video_priv *priv = dev_get_uclass_priv(dev);
 	char name[30], drv[15], *str;
 	const char *drv_name = drv;
@@ -618,6 +633,16 @@ static int video_post_probe(struct udevice *dev)
 		}
 	}
 
+	/* register cyclic as soon as the first video device is probed */
+	if (CONFIG_IS_ENABLED(CYCLIC) && (gd->flags && GD_FLG_RELOC) &&
+	    !uc_priv->cyc_active) {
+		uint ms = CONFIG_IF_ENABLED_INT(CYCLIC, VIDEO_SYNC_CYCLIC_MS);
+
+		cyclic_register(&uc_priv->cyc, video_idle, ms * 1000,
+				"video_init");
+		uc_priv->cyc_active = true;
+	}
+
 	return 0;
 };
 
@@ -657,6 +682,18 @@ static int video_post_bind(struct udevice *dev)
 	return 0;
 }
 
+__maybe_unused static int video_destroy(struct uclass *uc)
+{
+	struct video_uc_priv *uc_priv = uclass_get_priv(uc);
+
+	if (uc_priv->cyc_active) {
+		cyclic_unregister(&uc_priv->cyc);
+		uc_priv->cyc_active = false;
+	}
+
+	return 0;
+}
+
 UCLASS_DRIVER(video) = {
 	.id		= UCLASS_VIDEO,
 	.name		= "video",
@@ -666,4 +703,5 @@ UCLASS_DRIVER(video) = {
 	.priv_auto	= sizeof(struct video_uc_priv),
 	.per_device_auto	= sizeof(struct video_priv),
 	.per_device_plat_auto	= sizeof(struct video_uc_plat),
+	CONFIG_IS_ENABLED(CYCLIC, (.destroy = video_destroy, ))
 };
-- 
2.34.1

[PATCH v3 4/5] sandbox: Increase cyclic CPU-time limit

[Simon Glass]

Now that sandbox is using cyclic for video, it trips the 1us time
limit. Updating the sandbox display often takes 20ms or more.

Increase the limit to 100ms to avoid a warning.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

(no changes since v1)

 common/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/common/Kconfig b/common/Kconfig
index 87b0ec3ea8f..83c81edac20 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -636,6 +636,7 @@ config SPL_CYCLIC
 
 config CYCLIC_MAX_CPU_TIME_US
 	int "Sets the max allowed time for a cyclic function in us"
+	default 100000 if SANDBOX  # sandbox video is quite slow
 	default 5000
 	help
 	  The max allowed time for a cyclic function in us. If a functions
-- 
2.34.1

[PATCH v3 5/5] sandbox: Drop video-sync in serial driver

[Simon Glass]

With sandbox, when U-Boot is waiting for input it syncs the video
display, since presumably the user has finished typing.

Now that cyclic is used for video syncing, we can drop this. Cyclic
will automatically call the video_idle() function when idle.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

(no changes since v2)

Changes in v2:
- Fix 'groth' and 'work-around' typos in cover letter

 drivers/serial/sandbox.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/serial/sandbox.c b/drivers/serial/sandbox.c
index ec0068e33d3..77a1558db68 100644
--- a/drivers/serial/sandbox.c
+++ b/drivers/serial/sandbox.c
@@ -138,8 +138,6 @@ static int sandbox_serial_pending(struct udevice *dev, bool input)
 		return 0;
 
 	os_usleep(100);
-	if (IS_ENABLED(CONFIG_VIDEO) && !IS_ENABLED(CONFIG_SPL_BUILD))
-		video_sync_all();
 	avail = membuff_putraw(&priv->buf, 100, false, &data);
 	if (!avail)
 		return 1;	/* buffer full */
-- 
2.34.1

Re: [PATCH v3 4/5] sandbox: Increase cyclic CPU-time limit

[Caleb Connolly]

Hi Simon,

On 04/07/2024 09:48, Simon Glass wrote:
> Now that sandbox is using cyclic for video, it trips the 1us time
> limit. Updating the sandbox display often takes 20ms or more.
> 
> Increase the limit to 100ms to avoid a warning.
> 
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
> 
> (no changes since v1)
> 
>   common/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/common/Kconfig b/common/Kconfig
> index 87b0ec3ea8f..83c81edac20 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -636,6 +636,7 @@ config SPL_CYCLIC
>   
>   config CYCLIC_MAX_CPU_TIME_US
>   	int "Sets the max allowed time for a cyclic function in us"
> +	default 100000 if SANDBOX  # sandbox video is quite slow

Won't this be the case for other boards as well? Maybe it would make 
sense to bump this unconditionally or adjust the cyclic API so users 
could provide a hint about how long they'll take to run.

Isn't 100ms a bit excessive just to flush a buffer?
>   	default 5000
>   	help
>   	  The max allowed time for a cyclic function in us. If a functions

-- 
// Caleb (they/them)

Re: [PATCH v3 0/5] video: Improve syncing performance with cyclic

[Caleb Connolly]

Hi Simon,

On 04/07/2024 09:48, Simon Glass wrote:
> Now that U-Boot has a background-processing feature, it is possible to
> reduce the amount of 'foreground' syncing of the display. At present
> this happens quite often.
> 
> Foreground syncing blocks all other processing, sometimes for 10ms or
> more. When pasting commands into U-Boot over the UART, this typically
> result in characters being dropped. For example, on rpi_4 it isn't
> possible to paste in more than 35 characters before things fail. This
> makes updating the environment or entering long commands very painful
> over the console, since text must be pasted in chunks, or the
> vidconsole device must be dropped from stdout.

I'm not intimately familiar with U-Boots event loop, but to me this 
sounds more like a bug in the console code. I can confirm this issue 
appears on Qualcomm platforms with the GENI serial driver, I tried 
enabling CONFIG_SERIAL_RX_BUFFER and it seemed to help significantly 
(though there were still a few dropped characters when pasting).

Of note, the USB ACM serial driver doesn't seem to have any issues here, 
presumably since it isn't restricted by the baud rate.

If there is an abort, does this approach still ensure that it gets 
printed properly on the video console?

Kind regards,
> 
> This series introduces background syncing, enabled by default for
> boards which use video. The sync rates for foreground and background
> are configurable.
> 
> With this series it is possible to paste in any amount of text to the
> command line. Some sandbox-specific workarounds can now be removed and
> sandbox video (./u-boot -Dl) is significantly more responsive.
> 
> This obviously increases code size, since it enables a subsystem not
> normally used by default. However it only applies to boards which have
> VIDEO enabled, which are presumably less worried about memory space
> since the video code is fairly large.
> 
> Also it is possible to disable CMD_CYCLIC and reduce the growth to:
> 
>     aarch64: (for 1/1 boards) all +1081.0 rodata +65.0 text +1016.0
>         arm: (for 1/1 boards) all +945.0 rodata +65.0 text +880.0
> 
> Without that, the increase doubles.
> 
> It is of course possible to disable CYCLIC and still use VIDEO but this
> reverts to the current behaviour
> 
> Changes in v3:
> - Drop inclusion of kconfig.h in cyclic.h
> - Adapt to new cyclic API
> 
> Changes in v2:
> - Add an SPL_CYCLIC symbol
> - Add a lot more explanation about the header files
> - Expand help for CONFIG_VIDEO
> - Fix 'groth' and 'work-around' typos in cover letter
> 
> Simon Glass (5):
>    cyclic: Add a symbol for SPL
>    video: Move last_sync to private data
>    video: Use cyclic to handle video sync
>    sandbox: Increase cyclic CPU-time limit
>    sandbox: Drop video-sync in serial driver
> 
>   common/Kconfig                    |  9 ++++++
>   common/Makefile                   |  2 +-
>   drivers/serial/sandbox.c          |  2 --
>   drivers/video/Kconfig             | 35 +++++++++++++++++++++
>   drivers/video/video-uclass.c      | 52 +++++++++++++++++++++++++------
>   drivers/watchdog/Kconfig          |  1 +
>   include/asm-generic/global_data.h |  2 +-
>   include/cyclic.h                  |  5 +--
>   include/video.h                   |  2 ++
>   9 files changed, 95 insertions(+), 15 deletions(-)
> 

-- 
// Caleb (they/them)

Re: [PATCH v3 4/5] sandbox: Increase cyclic CPU-time limit

[Simon Glass]

Hi Caleb,

On Thu, 4 Jul 2024 at 16:02, Caleb Connolly <caleb.connolly@linaro.org> wrote:
>
> Hi Simon,
>
> On 04/07/2024 09:48, Simon Glass wrote:
> > Now that sandbox is using cyclic for video, it trips the 1us time
> > limit. Updating the sandbox display often takes 20ms or more.
> >
> > Increase the limit to 100ms to avoid a warning.
> >
> > Signed-off-by: Simon Glass <sjg@chromium.org>
> > ---
> >
> > (no changes since v1)
> >
> >   common/Kconfig | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/common/Kconfig b/common/Kconfig
> > index 87b0ec3ea8f..83c81edac20 100644
> > --- a/common/Kconfig
> > +++ b/common/Kconfig
> > @@ -636,6 +636,7 @@ config SPL_CYCLIC
> >
> >   config CYCLIC_MAX_CPU_TIME_US
> >       int "Sets the max allowed time for a cyclic function in us"
> > +     default 100000 if SANDBOX  # sandbox video is quite slow
>
> Won't this be the case for other boards as well? Maybe it would make
> sense to bump this unconditionally or adjust the cyclic API so users
> could provide a hint about how long they'll take to run.
>
> Isn't 100ms a bit excessive just to flush a buffer?

I have not noticed this problem on the few boards I have tested with,
i.e. sandbox seems to be unique.

sandbox does seem to take quite a while...it is updating the display
using SDL. You can try it out on your machine if you like, and see
what happens.

> >       default 5000
> >       help
> >         The max allowed time for a cyclic function in us. If a functions
>
> --
> // Caleb (they/them)

Regards,
Simon

Re: [PATCH v3 0/5] video: Improve syncing performance with cyclic

[Simon Glass]

Hi Caleb,

On Thu, 4 Jul 2024 at 16:17, Caleb Connolly <caleb.connolly@linaro.org> wrote:
>
> Hi Simon,
>
> On 04/07/2024 09:48, Simon Glass wrote:
> > Now that U-Boot has a background-processing feature, it is possible to
> > reduce the amount of 'foreground' syncing of the display. At present
> > this happens quite often.
> >
> > Foreground syncing blocks all other processing, sometimes for 10ms or
> > more. When pasting commands into U-Boot over the UART, this typically
> > result in characters being dropped. For example, on rpi_4 it isn't
> > possible to paste in more than 35 characters before things fail. This
> > makes updating the environment or entering long commands very painful
> > over the console, since text must be pasted in chunks, or the
> > vidconsole device must be dropped from stdout.
>
> I'm not intimately familiar with U-Boots event loop, but to me this
> sounds more like a bug in the console code. I can confirm this issue
> appears on Qualcomm platforms with the GENI serial driver, I tried
> enabling CONFIG_SERIAL_RX_BUFFER and it seemed to help significantly
> (though there were still a few dropped characters when pasting).

Thanks for digging into this. Yes I agree.

The fix I have been contemplating is to adjust video_sync() to only
flush the cache if 'force' is given, then have vidconsole_putc() pass
force=true if a newline is written.

>
> Of note, the USB ACM serial driver doesn't seem to have any issues here,
> presumably since it isn't restricted by the baud rate.

Or it might just have a large serial buffer?

>
> If there is an abort, does this approach still ensure that it gets
> printed properly on the video console?

What sort of abort?

>
> Kind regards,
> >
> > This series introduces background syncing, enabled by default for
> > boards which use video. The sync rates for foreground and background
> > are configurable.
> >
> > With this series it is possible to paste in any amount of text to the
> > command line. Some sandbox-specific workarounds can now be removed and
> > sandbox video (./u-boot -Dl) is significantly more responsive.
> >
> > This obviously increases code size, since it enables a subsystem not
> > normally used by default. However it only applies to boards which have
> > VIDEO enabled, which are presumably less worried about memory space
> > since the video code is fairly large.
> >
> > Also it is possible to disable CMD_CYCLIC and reduce the growth to:
> >
> >     aarch64: (for 1/1 boards) all +1081.0 rodata +65.0 text +1016.0
> >         arm: (for 1/1 boards) all +945.0 rodata +65.0 text +880.0
> >
> > Without that, the increase doubles.
> >
> > It is of course possible to disable CYCLIC and still use VIDEO but this
> > reverts to the current behaviour
> >
> > Changes in v3:
> > - Drop inclusion of kconfig.h in cyclic.h
> > - Adapt to new cyclic API
> >
> > Changes in v2:
> > - Add an SPL_CYCLIC symbol
> > - Add a lot more explanation about the header files
> > - Expand help for CONFIG_VIDEO
> > - Fix 'groth' and 'work-around' typos in cover letter
> >
> > Simon Glass (5):
> >    cyclic: Add a symbol for SPL
> >    video: Move last_sync to private data
> >    video: Use cyclic to handle video sync
> >    sandbox: Increase cyclic CPU-time limit
> >    sandbox: Drop video-sync in serial driver
> >
> >   common/Kconfig                    |  9 ++++++
> >   common/Makefile                   |  2 +-
> >   drivers/serial/sandbox.c          |  2 --
> >   drivers/video/Kconfig             | 35 +++++++++++++++++++++
> >   drivers/video/video-uclass.c      | 52 +++++++++++++++++++++++++------
> >   drivers/watchdog/Kconfig          |  1 +
> >   include/asm-generic/global_data.h |  2 +-
> >   include/cyclic.h                  |  5 +--
> >   include/video.h                   |  2 ++
> >   9 files changed, 95 insertions(+), 15 deletions(-)
> >
>
> --
> // Caleb (they/them)

Regards,
Simon

Re: [PATCH v3 0/5] video: Improve syncing performance with cyclic

[Anatolij Gustschin]

Hi Simon,

On Thu,  4 Jul 2024 08:48:54 +0100
Simon Glass sjg@chromium.org wrote:

> Now that U-Boot has a background-processing feature, it is possible to
> reduce the amount of 'foreground' syncing of the display. At present
> this happens quite often.

This series breaks turris_1x_sdcard SPL build:

 https://source.denx.de/u-boot/custodians/u-boot-video/-/jobs/878470#L646

Should we enable CONFIG_SPL_CYCLIC for this board to fix this?

--
Anatolij

Re: [PATCH v3 0/5] video: Improve syncing performance with cyclic

[Simon Glass]

Hi Anatolij,

On Tue, 30 Jul 2024 at 17:05, Anatolij Gustschin <agust@denx.de> wrote:
>
> Hi Simon,
>
> On Thu,  4 Jul 2024 08:48:54 +0100
> Simon Glass sjg@chromium.org wrote:
>
> > Now that U-Boot has a background-processing feature, it is possible to
> > reduce the amount of 'foreground' syncing of the display. At present
> > this happens quite often.
>
> This series breaks turris_1x_sdcard SPL build:
>
>  https://source.denx.de/u-boot/custodians/u-boot-video/-/jobs/878470#L646
>
> Should we enable CONFIG_SPL_CYCLIC for this board to fix this?

Oh, my passing run was from a month ago[1].

I think I need to change a Kconfig condition. Let me try that and resend.

Regards,
Simon

[1] https://source.denx.de/u-boot/custodians/u-boot-dm/-/pipelines/21437

[PATCH v3 0/5] video: Improve syncing performance with cyclic

[Simon Glass]

Now that U-Boot has a background-processing feature, it is possible to
reduce the amount of 'foreground' syncing of the display. At present
this happens quite often.

Foreground syncing blocks all other processing, sometimes for 10ms or
more. When pasting commands into U-Boot over the UART, this typically
result in characters being dropped. For example, on rpi_4 it isn't
possible to paste in more than 35 characters before things fail. This
makes updating the environment or entering long commands very painful
over the console, since text must be pasted in chunks, or the
vidconsole device must be dropped from stdout.

This series introduces background syncing, enabled by default for
boards which use video. The sync rates for foreground and background
are configurable.

With this series it is possible to paste in any amount of text to the
command line. Some sandbox-specific workarounds can now be removed and
sandbox video (./u-boot -Dl) is significantly more responsive.

This obviously increases code size, since it enables a subsystem not
normally used by default. However it only applies to boards which have
VIDEO enabled, which are presumably less worried about memory space
since the video code is fairly large.

Also it is possible to disable CMD_CYCLIC and reduce the growth to:

   aarch64: (for 1/1 boards) all +1081.0 rodata +65.0 text +1016.0
       arm: (for 1/1 boards) all +945.0 rodata +65.0 text +880.0

Without that, the increase doubles.

It is of course possible to disable CYCLIC and still use VIDEO but this
reverts to the current behaviour

Changes in v4:
- Imply SPL_CYCLIC if WATCHDOG is enabled

Changes in v3:
- Drop inclusion of kconfig.h in cyclic.h
- Adapt to new cyclic API

Changes in v2:
- Add an SPL_CYCLIC symbol
- Add a lot more explanation about the header files
- Expand help for CONFIG_VIDEO
- Fix 'groth' and 'work-around' typos in cover letter

Simon Glass (5):
  cyclic: Add a symbol for SPL
  video: Move last_sync to private data
  video: Use cyclic to handle video sync
  sandbox: Increase cyclic CPU-time limit
  sandbox: Drop video-sync in serial driver

 common/Kconfig                    |  9 ++++++
 common/Makefile                   |  2 +-
 drivers/serial/sandbox.c          |  2 --
 drivers/video/Kconfig             | 35 +++++++++++++++++++++
 drivers/video/video-uclass.c      | 52 +++++++++++++++++++++++++------
 drivers/watchdog/Kconfig          |  2 ++
 include/asm-generic/global_data.h |  2 +-
 include/cyclic.h                  |  5 +--
 include/video.h                   |  2 ++
 9 files changed, 96 insertions(+), 15 deletions(-)

-- 
2.34.1

Re: [PATCH v3 0/5] video: Improve syncing performance with cyclic

[Simon Glass]

Hi,

On Wed, 31 Jul 2024 at 08:41, Simon Glass <sjg@chromium.org> wrote:
>
> Now that U-Boot has a background-processing feature, it is possible to
> reduce the amount of 'foreground' syncing of the display. At present
> this happens quite often.
>
> Foreground syncing blocks all other processing, sometimes for 10ms or
> more. When pasting commands into U-Boot over the UART, this typically
> result in characters being dropped. For example, on rpi_4 it isn't
> possible to paste in more than 35 characters before things fail. This
> makes updating the environment or entering long commands very painful
> over the console, since text must be pasted in chunks, or the
> vidconsole device must be dropped from stdout.
>
> This series introduces background syncing, enabled by default for
> boards which use video. The sync rates for foreground and background
> are configurable.
>
> With this series it is possible to paste in any amount of text to the
> command line. Some sandbox-specific workarounds can now be removed and
> sandbox video (./u-boot -Dl) is significantly more responsive.
>
> This obviously increases code size, since it enables a subsystem not
> normally used by default. However it only applies to boards which have
> VIDEO enabled, which are presumably less worried about memory space
> since the video code is fairly large.
>
> Also it is possible to disable CMD_CYCLIC and reduce the growth to:
>
>    aarch64: (for 1/1 boards) all +1081.0 rodata +65.0 text +1016.0
>        arm: (for 1/1 boards) all +945.0 rodata +65.0 text +880.0
>
> Without that, the increase doubles.
>
> It is of course possible to disable CYCLIC and still use VIDEO but this
> reverts to the current behaviour
>
> Changes in v4:
> - Imply SPL_CYCLIC if WATCHDOG is enabled
>
> Changes in v3:
> - Drop inclusion of kconfig.h in cyclic.h
> - Adapt to new cyclic API
>
> Changes in v2:
> - Add an SPL_CYCLIC symbol
> - Add a lot more explanation about the header files
> - Expand help for CONFIG_VIDEO
> - Fix 'groth' and 'work-around' typos in cover letter
>
> Simon Glass (5):
>   cyclic: Add a symbol for SPL
>   video: Move last_sync to private data
>   video: Use cyclic to handle video sync
>   sandbox: Increase cyclic CPU-time limit
>   sandbox: Drop video-sync in serial driver
>
>  common/Kconfig                    |  9 ++++++
>  common/Makefile                   |  2 +-
>  drivers/serial/sandbox.c          |  2 --
>  drivers/video/Kconfig             | 35 +++++++++++++++++++++
>  drivers/video/video-uclass.c      | 52 +++++++++++++++++++++++++------
>  drivers/watchdog/Kconfig          |  2 ++
>  include/asm-generic/global_data.h |  2 +-
>  include/cyclic.h                  |  5 +--
>  include/video.h                   |  2 ++
>  9 files changed, 96 insertions(+), 15 deletions(-)
>
> --
> 2.34.1
>

That should be v4, so I will resend this.

Regards,
Simon

Re: [PATCH v3 0/5] video: Improve syncing performance with cyclic

[Anatolij Gustschin]

Hi Simon,

On Wed, 31 Jul 2024 08:38:35 -0600
Simon Glass sjg@chromium.org wrote:

> Hi Anatolij,
> 
> On Tue, 30 Jul 2024 at 17:05, Anatolij Gustschin <agust@denx.de> wrote:
> >
> > Hi Simon,
> >
> > On Thu,  4 Jul 2024 08:48:54 +0100
> > Simon Glass sjg@chromium.org wrote:
> >  
> > > Now that U-Boot has a background-processing feature, it is possible to
> > > reduce the amount of 'foreground' syncing of the display. At present
> > > this happens quite often.  
> >
> > This series breaks turris_1x_sdcard SPL build:
> >
> >  https://source.denx.de/u-boot/custodians/u-boot-video/-/jobs/878470#L646
> >
> > Should we enable CONFIG_SPL_CYCLIC for this board to fix this?  
> 
> Oh, my passing run was from a month ago[1].

I see, turris_1x board patches were merged later.

> I think I need to change a Kconfig condition. Let me try that and resend.

OK, thanks!

--
Anatolij