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

Joe Hershberger
2012-10-25T22:43:20Z

Hi Allen,

On Thu, Oct 25, 2012 at 4:19 PM, Allen Martin <amartin@nvidia.com> wrote:
> On Thu, Oct 25, 2012 at 02:02:55PM -0700, Simon Glass wrote:
>> Hi,
>>
>> On Thu, Oct 25, 2012 at 12:03 PM, Marek Vasut <marex@denx.de> wrote:
>> > Dear Simon Glass,
>> >
>> >> Hi,
>> >>
>> >> On Mon, Oct 22, 2012 at 10:23 AM, Allen Martin <amartin@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?
>> >
>> > Definitelly not. We should fix the iomux.c , possibly by flipping the inequation
>> > mark as a short term solution.
>>
>> OK that's fine. Is someone working on a patch?
>>
>
> I'll send out my proposal for a patch. Unfortunately I don't have a
> board with multiple serial ports to correctly test CONFIG_SERIAL_MULTI

One of the boards I'm working on does this (has more than one). At
least before the serial rework from Marek, the stdout was either the
serial device directly (each serial device was added as a console
device as well) so the serial setting was redundant. You could just
set them directly to the serial port (which is more flexible).

I had two patches (not sent to ML before Marek made them highly
conflicting) that take the opposite approach you were, since it
preserves the flexibility. It removed the "serial" setting to each of
the std* variables and instead sets it to the default serial device.
I'll remake that patch on top of the new serial landscape sometime
soon.

-Joe