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

Stuart Yoder
2016-08-29T21:10:09Z

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd at arndb.de]
> Sent: Monday, August 29, 2016 3:38 PM
> To: linux-arm-kernel at lists.infradead.org
> Cc: Stuart Yoder <stuart.yoder@nxp.com>; devicetree at vger.kernel.org; shawnguo at kernel.org
> Subject: Re: [PATCH 1/2] arm64: dts: updates serial aliases for ls1043a rdb and qds boards
>
> 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 <stuart.yoder@nxp.com>
> > > 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?

Yes, that's the case with u-boot's defconfig. I'm still trying to
find out whether that mutual exlusivity was a firmware decision or
a hardware limitation.

Stuart