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

Marek Vasut
2012-10-26T10:22:32Z

Dear Joe Hershberger,

> 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)

I know, he's such a bastard, always breaking stuff and interfering with other
people's work !

> 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.

Actually, I'd like to merge the serial stuff and stdio stuff into one. So
"setenv stdX serial" would be replaced with "setenv stdX <serial_driver_name>".
I think that's the approach to take. But it'd break many boards.

Best regards,
Marek Vasut