Re: [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops

[Andy Shevchenko]

On Thu, May 17, 2018 at 4:56 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> * Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> [180516 13:12]:
>> On Wed, 2018-05-16 at 12:47 +0200, Sebastian Andrzej Siewior wrote:
>> > But since I am on it. You have to enable runtime-PM for the UART. So
>> > what is the problem if you simply don't enable it for the UART which
>> > used as the kernel console?
>>
>> How do I know at the ->probe() time that device in question is going to
>> be kernel console? Maybe I missed simple way of it.
>
> Hmm parse the kernel cmdline maybe? :)
>
> BTW, kernel already has earlycon doing exactly what you're trying to do.

I'm sorry, I didn't follow. What exactly earlycon does?

The problem is in 8250 driver. The issue with runtime PM used in atomic context.
So, I can, of course just remove callbacks from the console ->write().
Though it will prevent to use kernel console anyway.

-- 
With Best Regards,
Andy Shevchenko