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

[Tony Lindgren]

* Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> [180718 14:54]:
> On Wed, 2018-05-23 at 11:00 -0700, Tony Lindgren wrote:
> > I thought you said earlier the issue was that you wanted to keep
> > the console enabled all the time and never idle?
> 
> Yes, for kernel console.
> To be clear, if user supplies "console=ttySx" it keeps powered on
> always. But if there is no such parameter, we are fine with RPM.

I'm fine with that as long as we have a way to detach or disable
kernel console from userspace after booting so the console uart can
idle.

> Letting kernel console do power management on the systems without
> irq_safe hack is dangerous in terms of loosing important data (crash, or
> some other stuff which needs atomic context: kgdb?).

Yes in the long run we should get rid of all pm_runtime_irq_safe()
use. It increases the parent dev PM runtime usage count permanently
blocking the whole domain from idling.

Regards,

Tony