[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 at 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 at 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 at 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 at 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