2020-03-11 11:22:25

by Chunyan Zhang

Subject: [RESEND PATCH] arm64: dts: specify console via command line

From: Chunyan Zhang <[email protected]>

The SPRD serial driver need to know which serial port would be used as
console in an early period during initialization, otherwise console
init would fail since we added this feature[1].

So this patch add console to command line via devicetree.

[1] https://lore.kernel.org/lkml/[email protected]/

Signed-off-by: Chunyan Zhang <[email protected]>
---
I guess no comments on this, so resending this and add [email protected],
hope Arnd or Olof can help to merge into arch_arm tree.

Thanks,
Chunyan
---
arch/arm64/boot/dts/sprd/sp9863a-1h10.dts | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts b/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
index 2047f7a74265..510f65f4d8b8 100644
--- a/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
+++ b/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
@@ -28,7 +28,7 @@

chosen {
stdout-path = "serial1:115200n8";
- bootargs = "earlycon";
+ bootargs = "earlycon console=ttyS1";
};
};

--
2.20.1

2020-03-11 14:34:16

by Arnd Bergmann

Subject: Re: [RESEND PATCH] arm64: dts: specify console via command line

On Wed, Mar 11, 2020 at 12:21 PM Chunyan Zhang <[email protected]> wrote:
>

> diff --git a/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts b/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
> index 2047f7a74265..510f65f4d8b8 100644
> --- a/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
> +++ b/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
> @@ -28,7 +28,7 @@
>
> chosen {
> stdout-path = "serial1:115200n8";
> - bootargs = "earlycon";
> + bootargs = "earlycon console=ttyS1";
> };
> };

Hi Chunyan,

I would expect that you need to either specify the stdout-path, or the console=
kernel parameter, but not both.

If earlycon was used, shouldn't the driver know which port is the console?

Arnd

2020-03-12 07:35:46

by Chunyan Zhang

Subject: Re: [RESEND PATCH] arm64: dts: specify console via command line

Hi Arnd,

On Wed, 11 Mar 2020 at 22:31, Arnd Bergmann <[email protected]> wrote:
>
> On Wed, Mar 11, 2020 at 12:21 PM Chunyan Zhang <[email protected]> wrote:
> >
>
> > diff --git a/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts b/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
> > index 2047f7a74265..510f65f4d8b8 100644
> > --- a/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
> > +++ b/arch/arm64/boot/dts/sprd/sp9863a-1h10.dts
> > @@ -28,7 +28,7 @@
> >
> > chosen {
> > stdout-path = "serial1:115200n8";
> > - bootargs = "earlycon";
> > + bootargs = "earlycon console=ttyS1";
> > };
> > };
>
> Hi Chunyan,
>
> I would expect that you need to either specify the stdout-path, or the console=
> kernel parameter, but not both.
>

Ok, now I know how to fix the problem without adding 'console=' :)
of_console_check() [1] can tell if a given port is the console by
reading 'stdout-path'.
I will address this issue in serial driver.

Thanks for your reminder,
Chunyan

[1] https://elixir.bootlin.com/linux/v5.6-rc5/source/drivers/of/base.c#L2135

> If earlycon was used, shouldn't the driver know which port is the console?
>
> Arnd