Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20200311112120.30890-1-zhang.lyra@gmail.com> <CAK8P3a12iN4HzN3HsRSBJPLpwJzdVwhrK7Mje0V6eW3Lvd77iw@mail.gmail.com>
In-Reply-To: <CAK8P3a12iN4HzN3HsRSBJPLpwJzdVwhrK7Mje0V6eW3Lvd77iw@mail.gmail.com>
From:   Chunyan Zhang <zhang.lyra@gmail.com>
Date:   Thu, 12 Mar 2020 15:34:34 +0800
Message-ID: <CAAfSe-sKXT5K_m8f0vhCqSVsH1Sma1cSfiidiCFAGKS6eKFMkg@mail.gmail.com>
Subject: Re: [RESEND PATCH] arm64: dts: specify console via command line
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     SoC Team <soc@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        DTML <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Orson Zhai <orsonzhai@gmail.com>,
        Baolin Wang <baolin.wang7@gmail.com>,
        Chunyan Zhang <chunyan.zhang@unisoc.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Arnd,

On Wed, 11 Mar 2020 at 22:31, Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Wed, Mar 11, 2020 at 12:21 PM Chunyan Zhang <zhang.lyra@gmail.com> 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