[PATCH] console: Add option to keep it silent until env is loaded

[PATCH] console: Add option to keep it silent until env is loaded

[Harald Seiler]

Add a config-option which forces the console to stay silent until the
proper environment is loaded from flash.

This is important when the default environment does not silence the
console but no output must be printed when 'silent' is set in the flash
environment.

After the environment from flash is loaded, the console will be
silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
used, the buffer will now be flushed if the console should not be
silenced.

Signed-off-by: Harald Seiler <hws@denx.de>
---
 common/Kconfig   | 10 ++++++++++
 common/console.c |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/common/Kconfig b/common/Kconfig
index fdcf4536d0..506a4d6245 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -120,6 +120,16 @@ config SILENT_CONSOLE_UPDATE_ON_RELOC
 	  (e.g. NAND). This option makes the value of the 'silent'
 	  environment variable take effect at relocation.
 
+config SILENT_CONSOLE_UNTIL_ENV
+	bool "Keep console silent until environment is loaded"
+	depends on SILENT_CONSOLE
+	help
+	  This option makes sure U-Boot will never use the console unless the
+	  environment from flash does not contain the 'silent' variable.  If
+	  set, the console is kept silent until after the environment was
+	  loaded.  Use this in combination with PRE_CONSOLE_BUFFER to print out
+	  earlier messages after loading the environment when allowed.
+
 config PRE_CONSOLE_BUFFER
 	bool "Buffer characters before the console is available"
 	help
diff --git a/common/console.c b/common/console.c
index 0013d183ae..f0f5a9cf80 100644
--- a/common/console.c
+++ b/common/console.c
@@ -893,6 +893,11 @@ static bool console_update_silent(void)
 	if (!IS_ENABLED(CONFIG_SILENT_CONSOLE))
 		return false;
 
+	if (IS_ENABLED(CONFIG_SILENT_CONSOLE_UNTIL_ENV) && !(gd->flags & GD_FLG_ENV_READY)) {
+		gd->flags |= GD_FLG_SILENT;
+		return false;
+	}
+
 	if (env_get("silent")) {
 		gd->flags |= GD_FLG_SILENT;
 		return false;
-- 
2.36.1

Re: [PATCH] console: Add option to keep it silent until env is loaded

[Simon Glass]

Hi Harald,

On Wed, 6 Jul 2022 at 05:19, Harald Seiler <hws@denx.de> wrote:
>
> Add a config-option which forces the console to stay silent until the
> proper environment is loaded from flash.
>
> This is important when the default environment does not silence the
> console but no output must be printed when 'silent' is set in the flash
> environment.
>
> After the environment from flash is loaded, the console will be
> silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
> used, the buffer will now be flushed if the console should not be
> silenced.
>
> Signed-off-by: Harald Seiler <hws@denx.de>
> ---
>  common/Kconfig   | 10 ++++++++++
>  common/console.c |  5 +++++
>  2 files changed, 15 insertions(+)

This seems OK to me. You might want to implement the silent-console
device tree property in console_update_silent() too, which was dropped
in the conversion to driver model.

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

Re: [PATCH] console: Add option to keep it silent until env is loaded

[Harald Seiler]

Hi Simon,

On Tue, 2022-07-12 at 04:58 -0600, Simon Glass wrote:
> Hi Harald,
> 
> On Wed, 6 Jul 2022 at 05:19, Harald Seiler <hws@denx.de> wrote:
> > 
> > Add a config-option which forces the console to stay silent until the
> > proper environment is loaded from flash.
> > 
> > This is important when the default environment does not silence the
> > console but no output must be printed when 'silent' is set in the flash
> > environment.
> > 
> > After the environment from flash is loaded, the console will be
> > silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
> > used, the buffer will now be flushed if the console should not be
> > silenced.
> > 
> > Signed-off-by: Harald Seiler <hws@denx.de>
> > ---
> >  common/Kconfig   | 10 ++++++++++
> >  common/console.c |  5 +++++
> >  2 files changed, 15 insertions(+)
> 
> This seems OK to me. You might want to implement the silent-console
> device tree property in console_update_silent() too, which was dropped
> in the conversion to driver model.

This looks interesting, I'll have to look into it.

Do you know if there's any effort towards supporting such a flag in the
kernel as well?  I had to remove the serial console property from my DT
and instead pass console info via cmdline to make the silent console
work.  A "pure DT" solution of any sort would have been nicer of
course...

-- 
Harald

Re: [PATCH] console: Add option to keep it silent until env is loaded

[Simon Glass]

Hi Harald,

On Tue, 12 Jul 2022 at 05:58, Harald Seiler <hws@denx.de> wrote:
>
> Hi Simon,
>
> On Tue, 2022-07-12 at 04:58 -0600, Simon Glass wrote:
> > Hi Harald,
> >
> > On Wed, 6 Jul 2022 at 05:19, Harald Seiler <hws@denx.de> wrote:
> > >
> > > Add a config-option which forces the console to stay silent until the
> > > proper environment is loaded from flash.
> > >
> > > This is important when the default environment does not silence the
> > > console but no output must be printed when 'silent' is set in the flash
> > > environment.
> > >
> > > After the environment from flash is loaded, the console will be
> > > silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
> > > used, the buffer will now be flushed if the console should not be
> > > silenced.
> > >
> > > Signed-off-by: Harald Seiler <hws@denx.de>
> > > ---
> > >  common/Kconfig   | 10 ++++++++++
> > >  common/console.c |  5 +++++
> > >  2 files changed, 15 insertions(+)
> >
> > This seems OK to me. You might want to implement the silent-console
> > device tree property in console_update_silent() too, which was dropped
> > in the conversion to driver model.
>
> This looks interesting, I'll have to look into it.
>
> Do you know if there's any effort towards supporting such a flag in the
> kernel as well?  I had to remove the serial console property from my DT
> and instead pass console info via cmdline to make the silent console
> work.  A "pure DT" solution of any sort would have been nicer of
> course...

The console's 'silent' flag is propagated to Linux by dropping the
'console=' text from the bootargs. See fixup_silent_linux().

Regards,
Simon


>
> --
> Harald

Re: [PATCH] console: Add option to keep it silent until env is loaded

[Harald Seiler]

Hi Simon,

On Wed, 2022-07-13 at 09:28 -0600, Simon Glass wrote:
> Hi Harald,
> 
> On Tue, 12 Jul 2022 at 05:58, Harald Seiler <hws@denx.de> wrote:
> > 
> > Hi Simon,
> > 
> > On Tue, 2022-07-12 at 04:58 -0600, Simon Glass wrote:
> > > Hi Harald,
> > > 
> > > On Wed, 6 Jul 2022 at 05:19, Harald Seiler <hws@denx.de> wrote:
> > > > 
> > > > Add a config-option which forces the console to stay silent until the
> > > > proper environment is loaded from flash.
> > > > 
> > > > This is important when the default environment does not silence the
> > > > console but no output must be printed when 'silent' is set in the flash
> > > > environment.
> > > > 
> > > > After the environment from flash is loaded, the console will be
> > > > silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
> > > > used, the buffer will now be flushed if the console should not be
> > > > silenced.
> > > > 
> > > > Signed-off-by: Harald Seiler <hws@denx.de>
> > > > ---
> > > >  common/Kconfig   | 10 ++++++++++
> > > >  common/console.c |  5 +++++
> > > >  2 files changed, 15 insertions(+)
> > > 
> > > This seems OK to me. You might want to implement the silent-console
> > > device tree property in console_update_silent() too, which was dropped
> > > in the conversion to driver model.
> > 
> > This looks interesting, I'll have to look into it.
> > 
> > Do you know if there's any effort towards supporting such a flag in the
> > kernel as well?  I had to remove the serial console property from my DT
> > and instead pass console info via cmdline to make the silent console
> > work.  A "pure DT" solution of any sort would have been nicer of
> > course...
> 
> The console's 'silent' flag is propagated to Linux by dropping the
> 'console=' text from the bootargs. See fixup_silent_linux().

Right, this is what I am relying on right now.  The problem is that this
does not have any effect when `console=` is not used and the console is
instead passed using the `/chosen/stdout-path` DT property.

I was wondering whether U-Boot should maybe delete this property from
the DT passed to Linux when going silent...

(But of course this is unrelated to the original patch here)

-- 
Harald

Re: [PATCH] console: Add option to keep it silent until env is loaded

[Simon Glass]

Hi Harald,

On Mon, 18 Jul 2022 at 09:08, Harald Seiler <hws@denx.de> wrote:
>
> Hi Simon,
>
> On Wed, 2022-07-13 at 09:28 -0600, Simon Glass wrote:
> > Hi Harald,
> >
> > On Tue, 12 Jul 2022 at 05:58, Harald Seiler <hws@denx.de> wrote:
> > >
> > > Hi Simon,
> > >
> > > On Tue, 2022-07-12 at 04:58 -0600, Simon Glass wrote:
> > > > Hi Harald,
> > > >
> > > > On Wed, 6 Jul 2022 at 05:19, Harald Seiler <hws@denx.de> wrote:
> > > > >
> > > > > Add a config-option which forces the console to stay silent until the
> > > > > proper environment is loaded from flash.
> > > > >
> > > > > This is important when the default environment does not silence the
> > > > > console but no output must be printed when 'silent' is set in the flash
> > > > > environment.
> > > > >
> > > > > After the environment from flash is loaded, the console will be
> > > > > silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
> > > > > used, the buffer will now be flushed if the console should not be
> > > > > silenced.
> > > > >
> > > > > Signed-off-by: Harald Seiler <hws@denx.de>
> > > > > ---
> > > > >  common/Kconfig   | 10 ++++++++++
> > > > >  common/console.c |  5 +++++
> > > > >  2 files changed, 15 insertions(+)
> > > >
> > > > This seems OK to me. You might want to implement the silent-console
> > > > device tree property in console_update_silent() too, which was dropped
> > > > in the conversion to driver model.
> > >
> > > This looks interesting, I'll have to look into it.
> > >
> > > Do you know if there's any effort towards supporting such a flag in the
> > > kernel as well?  I had to remove the serial console property from my DT
> > > and instead pass console info via cmdline to make the silent console
> > > work.  A "pure DT" solution of any sort would have been nicer of
> > > course...
> >
> > The console's 'silent' flag is propagated to Linux by dropping the
> > 'console=' text from the bootargs. See fixup_silent_linux().
>
> Right, this is what I am relying on right now.  The problem is that this
> does not have any effect when `console=` is not used and the console is
> instead passed using the `/chosen/stdout-path` DT property.

OK.

>
> I was wondering whether U-Boot should maybe delete this property from
> the DT passed to Linux when going silent...

Yes it probably should!

>
> (But of course this is unrelated to the original patch here)

Regards,
Simon

Re: [PATCH] console: Add option to keep it silent until env is loaded

[Tom Rini]

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On Wed, Jul 06, 2022 at 01:19:10PM +0200, Harald Seiler wrote:

> Add a config-option which forces the console to stay silent until the
> proper environment is loaded from flash.
> 
> This is important when the default environment does not silence the
> console but no output must be printed when 'silent' is set in the flash
> environment.
> 
> After the environment from flash is loaded, the console will be
> silenced/unsilenced depending on it.  If PRE_CONSOLE_BUFFER is also
> used, the buffer will now be flushed if the console should not be
> silenced.
> 
> Signed-off-by: Harald Seiler <hws@denx.de>
> Reviewed-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

-- 
Tom

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