[PATCH] ARM: MXS: duckbill: set duart to serial0

[PATCH] ARM: MXS: duckbill: set duart to serial0

[Michael Grzeschik]

In the imx28.dtsi the serial0 is set to auart0 which is not the one
used on the duckbill. We set duart to serial0 so the console will be
properly set.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
---
 arch/arm/dts/imx28-duckbill.dts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/dts/imx28-duckbill.dts b/arch/arm/dts/imx28-duckbill.dts
index 2a995a7938..299c33e270 100644
--- a/arch/arm/dts/imx28-duckbill.dts
+++ b/arch/arm/dts/imx28-duckbill.dts
@@ -4,6 +4,10 @@
 	chosen {
 		stdout-path = &duart;
 	};
+
+	aliases {
+		serial0 = &duart;
+	};
 };
 
 &duart {
-- 
2.26.2


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Re: [PATCH] ARM: MXS: duckbill: set duart to serial0

[Lucas Stach]

Am Freitag, den 29.05.2020, 14:51 +0200 schrieb Michael Grzeschik:
> In the imx28.dtsi the serial0 is set to auart0 which is not the one
> used on the duckbill. We set duart to serial0 so the console will be
> properly set.

If the aliases are the same in the Barebox and Linux DTs there should
be no need to override the alias numbering in the individual board DTs.

Is the Linux driver ignoring the alias, or what is the issue being
fixed here?

Regards,
Lucas

> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
> ---
>  arch/arm/dts/imx28-duckbill.dts | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm/dts/imx28-duckbill.dts b/arch/arm/dts/imx28-
> duckbill.dts
> index 2a995a7938..299c33e270 100644
> --- a/arch/arm/dts/imx28-duckbill.dts
> +++ b/arch/arm/dts/imx28-duckbill.dts
> @@ -4,6 +4,10 @@
>  	chosen {
>  		stdout-path = &duart;
>  	};
> +
> +	aliases {
> +		serial0 = &duart;
> +	};
>  };
>  
>  &duart {


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Re: [PATCH] ARM: MXS: duckbill: set duart to serial0

[Michael Grzeschik]

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On Fri, May 29, 2020 at 03:56:53PM +0200, Lucas Stach wrote:
>Am Freitag, den 29.05.2020, 14:51 +0200 schrieb Michael Grzeschik:
>> In the imx28.dtsi the serial0 is set to auart0 which is not the one
>> used on the duckbill. We set duart to serial0 so the console will be
>> properly set.
>
>If the aliases are the same in the Barebox and Linux DTs there should
>be no need to override the alias numbering in the individual board DTs.
>
>Is the Linux driver ignoring the alias, or what is the issue being
>fixed here?

The duart (debugging uart) is completely missing in the aliases list.
The first set serial alias in dts/src/arm/imx28.dtsi is auart0, which
are the application uarts.

mgr

>> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
>> ---
>>  arch/arm/dts/imx28-duckbill.dts | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm/dts/imx28-duckbill.dts b/arch/arm/dts/imx28-
>> duckbill.dts
>> index 2a995a7938..299c33e270 100644
>> --- a/arch/arm/dts/imx28-duckbill.dts
>> +++ b/arch/arm/dts/imx28-duckbill.dts
>> @@ -4,6 +4,10 @@
>>  	chosen {
>>  		stdout-path = &duart;
>>  	};
>> +
>> +	aliases {
>> +		serial0 = &duart;
>> +	};
>>  };
>>
>>  &duart {
>
>

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Re: [PATCH] ARM: MXS: duckbill: set duart to serial0

[Sascha Hauer]

On Fri, May 29, 2020 at 03:56:53PM +0200, Lucas Stach wrote:
> Am Freitag, den 29.05.2020, 14:51 +0200 schrieb Michael Grzeschik:
> > In the imx28.dtsi the serial0 is set to auart0 which is not the one
> > used on the duckbill. We set duart to serial0 so the console will be
> > properly set.
> 
> If the aliases are the same in the Barebox and Linux DTs there should
> be no need to override the alias numbering in the individual board DTs.
> 
> Is the Linux driver ignoring the alias, or what is the issue being
> fixed here?

There are two different UARTs on the i.MX23/28, the duart ends up as
ttyAMAx in the kernel, the auart as ttyAPPx. Both drivers honor the
alias in the device tree. The upstream dtsi has:

                serial0 = &auart0;
                serial1 = &auart1;
                serial2 = &auart2;
                serial3 = &auart3;
                serial4 = &auart4;

With this we can't assign an alias to the duart anymore, serial0 is
already used. We could add a serial5 alias, but then we would get
ttyAMA5 instead of the desired ttyAMA0.

barebox tries to get an alias for the duart to set the proper console=
string for it. Now Michael changes the serial0 alias from &auart0 to
&duart. With this barebox can assign the correct console= string. Would
Linux be started with this device tree, &auart0 would still end up with
ttyAPP0 because it's the first free one.

This looks awful, but works for now. We are open for better suggestions
;)

Regards,
 Sascha


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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