[U-Boot] [PATCH] serial: add environment control for SERIAL_MULTI

[Marek Vasut]

Dear Joe Hershberger,

> Hi Allen,
> 
> On Thu, Oct 25, 2012 at 5:50 PM, Allen Martin <amartin at nvidia.com> wrote:
> > On Thu, Oct 25, 2012 at 03:46:01PM -0700, Joe Hershberger wrote:
> >> Hi Stephen,
> >> 
> >> On Thu, Oct 25, 2012 at 5:43 PM, Stephen Warren <swarren at wwwdotorg.org> 
wrote:
> >> > On 10/25/2012 03:59 PM, Allen Martin wrote:
> >> >> Add a new special environment variable "serial" that allows selection
> >> >> of serial device when CONFIG_SERIAL_MULTI is defined.  This replaces
> >> >> the existing calls to serial_assign() from cmd_nvedit.c and iomux.c
> >> >> that were not doing anything.
> >> > 
> >> > So I think this requires (for example) the following environment
> >> > variables:
> >> > 
> >> > stdout=serial
> >> > serial=eserial0
> >> > 
> >> > Is it possible to allow the following instead:
> >> > 
> >> > stdout=eserial0
> >> 
> >> This is precisely what the patch I had pre-Marek serial did.
> > 
> > In your patch would "stdout=serial" still work for case where there is
> > only one serial port?  I think it's important to try to preserve that
> > to no be too disruptive.
> 
> It used to support stdout=serial based on not being
> CONFIG_SERIAL_MULTI.  Now that that's gone, I'm guessing it would
> simply be based on only having one registered serial device.
> 
> >> > That way, one could presumably set:
> >> > 
> >> > stdout=eserial0,eserial3
> >> 
> >> Though it didn't allow this.
> > 
> > Shouldn't that be (nearly) transparent through iomux?
> 
> If that's what iomux does, then sure!  I haven't used I/O mux on a
> device before.

This is what we should do, indeed.

Best regards,
Marek Vasut