OMAP2+: PM/serial: hold console semaphore while OMAP UARTs are disabled

[Jean Pihet]

Hello Paul,

On Thu, Dec 2, 2010 at 8:23 AM, Paul Walmsley <paul at pwsan.com> wrote:
> Hello Jean
>
> On Thu, 25 Nov 2010, Jean Pihet wrote:
>
>> On Thu, Nov 25, 2010 at 6:35 PM, Paul Walmsley <paul at pwsan.com> wrote:
>> > On Thu, 25 Nov 2010, Jean Pihet wrote:
>> >> On Thu, Nov 25, 2010 at 12:49 AM, Paul Walmsley <paul at pwsan.com> wrote:
>> >> >
>> >> > The console semaphore must be held while the OMAP UART devices are
>> >> > disabled, lest a console write cause an ARM abort (and a kernel crash)
>> >> > when the underlying console device is inaccessible.  These crashes
>> >> > only occur when the console is on one of the OMAP internal serial
>> >> > ports.
>> >> This does not fix the issue for me on Beagle (console on ttyO2).
>> >>
>> >> Doing:
>> >>   / # echo 5 > /sys/devices/platform/omap/omap-hsuart.0/sleep_timeout
>> >>   / # echo 5 > /sys/devices/platform/omap/omap-hsuart.1/sleep_timeout
>> >>   / # echo 5 > /sys/devices/platform/omap/omap-hsuart.2/sleep_timeout
>> >> and waiting 5 seconds hangs the console.
>> >
>> > By the way, you write that the above situation "hangs the console."  Is it
>> > just the case that the console dies and the rest of the system is still
>> > alive, or does the whole system crash?
>> The console hangs, the rest of the system still runs.
>
> Just out of curiosity, if you send a few breaks to the OMAP over serial,
> does that cause the console to pay attention again?  CTRL-A F in minicom.
Yes it helps. In most cases sending 2-3 breaks resumes the UART console.

>
> - Paul

Jean