[PATCH] Documentation: admin-guide: add earlycon documentation for the sifive serial driver

[PATCH] Documentation: admin-guide: add earlycon documentation for the sifive serial driver

[Paul Walmsley]

Document earlycon usage for the SiFive serial port driver in the same
fashion as for the other serial port IP blocks, since the SiFive
serial port driver supports it.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Reported-by: Andreas Schwab <schwab@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
---
 Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c7ac2f3ac99f..90becb00221b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1106,6 +1106,12 @@
 			address must be provided, and the serial port must
 			already be setup and configured.
 
+		sifive,<addr>
+			Start an early, polled-mode console on a SiFive
+			serial port at the specified address.  The port must
+			already be setup and configured.  Options are not
+			yet supported.
+
 	earlyprintk=	[X86,SH,ARM,M68k,S390]
 			earlyprintk=vga
 			earlyprintk=sclp
-- 
2.23.0

Re: [PATCH] Documentation: admin-guide: add earlycon documentation for the sifive serial driver

[Geert Uytterhoeven]

Hi Paul,

On Wed, Oct 9, 2019 at 1:09 AM Paul Walmsley <paul.walmsley@sifive.com> wrote:
> Document earlycon usage for the SiFive serial port driver in the same
> fashion as for the other serial port IP blocks, since the SiFive
> serial port driver supports it.
>
> Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
> Reported-by: Andreas Schwab <schwab@suse.de>
> Cc: Christoph Hellwig <hch@lst.de>

Thanks for your patch!

Why do you need this?
I believe risc-v is DT-only, so if chosen/stdout-path is set up, just
passing "earlycon" (without any options) should work.

> ---
>  Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index c7ac2f3ac99f..90becb00221b 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1106,6 +1106,12 @@
>                         address must be provided, and the serial port must
>                         already be setup and configured.
>
> +               sifive,<addr>
> +                       Start an early, polled-mode console on a SiFive
> +                       serial port at the specified address.  The port must
> +                       already be setup and configured.  Options are not
> +                       yet supported.
> +
>         earlyprintk=    [X86,SH,ARM,M68k,S390]
>                         earlyprintk=vga
>                         earlyprintk=sclp

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] Documentation: admin-guide: add earlycon documentation for the sifive serial driver

[Andreas Schwab]

On Okt 09 2019, Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> I believe risc-v is DT-only, so if chosen/stdout-path is set up

If.  Currently, it isn't.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: [PATCH] Documentation: admin-guide: add earlycon documentation for the sifive serial driver

[Geert Uytterhoeven]

Hi Andreas,

On Wed, Oct 9, 2019 at 12:06 PM Andreas Schwab <schwab@suse.de> wrote:
> On Okt 09 2019, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > I believe risc-v is DT-only, so if chosen/stdout-path is set up
>
> If.  Currently, it isn't.

IC. So isn't it better to fix that, instead of pointing people to more obscure
legacy solutions?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] Documentation: admin-guide: add earlycon documentation for the sifive serial driver

[Paul Walmsley]

Hi Geert,

On Wed, 9 Oct 2019, Geert Uytterhoeven wrote:

> On Wed, Oct 9, 2019 at 12:06 PM Andreas Schwab <schwab@suse.de> wrote:
> > On Okt 09 2019, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > I believe risc-v is DT-only, so if chosen/stdout-path is set up
> >
> > If.  Currently, it isn't.
> 
> IC. So isn't it better to fix that, instead of pointing people to more obscure
> legacy solutions?

There's nothing that's RISC-V specific about the SiFive serial IP or 
its driver.  So the issue of whether RISC-V is DT-only or not probably 
shouldn't impact whether we document that the SiFive serial driver 
supports earlycon.

best regards,

- Paul