Subject: [PATCH 1/2] arm64: dts: updates serial aliases for ls1043a rdb and qds boards

From: [email-masked] (Arnd Bergmann)
Date: Mon, 29 Aug 2016 22:38:17 +0200

On Monday 29 August 2016, Stuart Yoder wrote:
> > -----Original Message-----
> > From: Arnd Bergmann [mailto:arnd at arndb.de]
> > Sent: Monday, August 29, 2016 6:01 AM
> > To: Stuart Yoder <[email-masked]>
> > Cc: devicetree at vger.kernel.org; linux-arm-kernel at lists.infradead.org; shawnguo at kernel.org
> > Subject: Re: [PATCH 1/2] arm64: dts: updates serial aliases for ls1043a rdb and qds boards
> > 
> > On Friday, August 26, 2016 3:46:20 PM CEST Stuart Yoder wrote:
> > > -               serial0 = &lpuart0;
> > > -               serial1 = &lpuart1;
> > > -               serial2 = &lpuart2;
> > > -               serial3 = &lpuart3;
> > > -               serial4 = &lpuart4;
> > > -               serial5 = &lpuart5;
> > > +               serial0 = &duart0;
> > > +               serial1 = &duart1;
> > > +               serial2 = &duart2;
> > > +               serial3 = &duart3;
> > 
> > It looks like your board has six uarts that are all driven with the
> > lpuart driver, but after the change, you only list four. Should
> > the serial4 and serial5 aliases keep pointing at lpuart devices
> > so you can still drive all physical connectors?
> 
> The only existing reference I can find to the serial aliases is if the
> OF_STDOUT_VIA_ALIAS is enabled in u-boot to specify the console.  The
> standard ls1043aqds_defconfig in u-boot specifies DUARTs for the console,
> which is why I'm proposing making the 4 DUARTs the default serial aliases
> in the device tree.

Ok, so they are mutually exclusive, and the last two ports are
unavailable in the default configuration?
 
> There is a separate defconfig in u-boot to enable/use LPUARTs instead
> of the normal DUARTs.  For that scenario, my take is that firmware should
> update the DT aliases to reflect the actual use of the serial ports.

Yes, makes sense.

> But, the default should be the DUARTs which is the normal case for this
> board, which is why this patch is changing them.

Ok

	Arnd