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

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Message-ID: <20180517134820.GI98604@atomide.com>
Date:   Thu, 17 May 2018 06:48:20 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops

* Sebastian Andrzej Siewior <bigeasy@...utronix.de> [180516 10:49]:
> On 2018-05-16 13:17:36 [+0300], Andy Shevchenko wrote:
> > > The output is usually short so there
> > > shouldn't be much benefit from using it.
> > 
> > > I remember Tony wanted runtime-pm on the kernel console, too. And he
> > > told me explicit how to test it so that it works. Once the UART goes
> > > into PM (down), the whole IP block can go into power save mode. The
> > > board can be woken up by sending a character via the UART. The first few
> > > (incoming / read) characters are lost until the IP block is up again the
> > > frequency stable. This is known / expected.
> > 
> > Don't consider world the OMAP only. The things more complicated if we
> > go out of it. Which I tried to explain in the commit message of patch
> > 2.
> 
> I am not saying the world is OMAP only. I just tried to explain how any
> why it got there and its purpose. I haven't NACKed it. I would believe
> that with that information and Tony not defending his use case or
> possible change it somehow so it is not standing in your way, Greg would
> have enough information to go your way.

The idea breaking PM seems silly to me considering that we've had
it working for years already.

Regards,

Tony