Re: [PATCH RESEND 0/2] two serial_core suspend/resume fixes

[Stanislav Brabec <sbrabec@suse.cz>]

Jason Wang wrote:

> > suspend:
> > - save hardware state
> >   
> How about move this part to driver specific level(i.e. pxa.c)
> > - but not physically stop it

Yes, I was thinking about it as well. It would be far the cleanest
solution that would prevent all ugly hacks in serial_core.c.

In addition to the standard suspend and resume there could be save_state
(and keep running) and resume_state (from save_state mode).

> Maybe stop it can save power on some platforms, moreover,
> it can prevent some unreadable chars

No, no_console_suspend is a special mode, required for suspend debugging
and not intended for production kernels. If you are debugging a kernel
that does not resume at all, you have no other way to collect debug
messages than keeping console in running state as long as possible.

This behavior of no_console_suspend should be kept even at cost of
higher power consumption during suspend in this mode, otherwise some
suspend failures may become undebugable.

I see just another "by design" problem: no_console_suspend keeps console
in running state. After the resume, kernel still thinks, that the
console is not suspended and it is possible to write to the console.
That is why early resume messages may be lost.

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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