[U-Boot] [PATCH 3/6] serial: Reorder serial_assign()

Simon Glass sjg at chromium.org
Thu Oct 25 20:09:03 CEST 2012


Hi,

On Mon, Oct 22, 2012 at 10:23 AM, Allen Martin <amartin at nvidia.com> wrote:
> On Sat, Oct 20, 2012 at 01:19:00AM -0700, Marek Vasut wrote:
>> Dear Allen Martin,
>>
>> [...]
>> >
>> > Hi Marek, the change to return value here broke serial output on
>> > tegra.  What I see is that the serial device name (s->name) is
>> > "eserial0" as set by serial_ns16550.c, and the name passed in from the
>> > stdout environment is "serial" so they don't match and it fails.  This
>> > always used to be ok because the return code didn't indicate failure
>> > and iomux_doenv() would continue on happily, but now it causes
>> > iomux_doenv() to fail and no printfs() work after that.
>> >
>> > Not sure what the right fix is, should stdout really be set to
>> > "eserial0"?  It seems "serial" should mean "the default serial device"
>> > which for the normal case is the one and only device.
>>
>> Looking at the source, the obvious course of action is to fix iomux.c .
>>
>
> I've been looking at this call to serial_assign() from iomux.c and I'm
> not convinced this code does anything meaningful at all.  It passes
> the name of a struct stdio_dev device which serial_assign() then tries
> to match against the registered struct serial_devices, which will
> never match.
>
> What I don't understand is the case where you have a board that
> actually has more than one physical serial port and how the mapping
> from stdio_dev to serial_device happens.
>
> Also, looking at the code to cmd_nvedit, I think your change also broke
> "setenv stdout" for boards that don't define CONFIG_CONSOLE_MUX.  We
> always have this on for tegra, so we don't go down this code path, but
> it looks identical to the code in iomux.c

Sorry if I missed it - what was the resolution here? Should we revert
that change?

Regards,
Simon

>
> -Allen
> --
> nvpublic
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