Re: ARC fails to boot on linux-next of 20140711

[Vineet Gupta]

Hi Rob,

On Friday 25 July 2014 07:45 PM, Rob Herring wrote:
> On Fri, Jul 25, 2014 at 6:02 AM, Vineet Gupta
> <Vineet.Gupta1@xxxxxxxxxxxx> wrote:
>> > Hi Grant,
>> >
>> > linux-next has a series for arc_uart (via tty tree) which converts it to generic
>> > earlycon and specifies console via /chosen/stdout-path vs.  an explicit param in
>> > /chose/bootargs
>> >
>> > 2014-06-24 9da433c0a0b5 ARC: [arcfpga] stdout-path now suffices for earlycon/console
>> >
>> > This relied on prev commit of yours (from linux next of 20140711), which seem to
>> > have disappeared now.
>> >
>> > 2014-03-27 a9296cf2d0b6 of: Create of_console_check() for selecting a console
>> > specified in /chosen
>> > 2014-03-27 cfa9cacc5dd3 of: Enable console on serial ports specified by
>> > /chosen/stdout-path
>> >
>> > Is there a specific reason for dropping these patches (or perhaps a merge to be
>> > merged). I cherry-picked both but still doesn't work.
>> >
>> > Can you please advise next step forward, before I go off debugging with those
>> > patches in.
> There's an issue that if you have stdout-path and "earlycon" on the
> command line, the kernel will switch to tty0 and disable the earlycon.
>
> This is the "fix", but I don't like adding the DT dependency into generic code:
>
> @@ -2382,7 +2386,7 @@ void register_console(struct console *newcon)
>                 if (newcon->setup == NULL ||
>                     newcon->setup(newcon, NULL) == 0) {
>                         newcon->flags |= CON_ENABLED;
> -                       if (newcon->device) {
> +                       if (newcon->device  && !of_stdout) {
>                                 newcon->flags |= CON_CONSDEV;
>                                 preferred_console = 0;
>                         }

The DT settings relevant for ARC, which enable generic-earlycon and
console-with-stdout-path are as follows

        chosen {
                bootargs = "earlycon";
                stdout-path = &arcuart0;
        };

....
                arcuart0: serial@c0fc1000 {
                        compatible = "snps,arc-uart";

And it works w/o above hunk, provided the 2 patches from Grant exist in linux-next
which they don't at the moment. I'm pretty confused how the hunk above comes into
picture.

And if not then I will have to get the ARC std-out patch reverted in tty-next as
it is broken.

Thx,
-Vineet
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