linux-kernel - Re: [PATCH] atmel_serial: update the powersave handler to match serial core

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Message-ID: <20080919181551.3507b34b@hskinnemo-gx745.norway.atmel.com>
Date:	Fri, 19 Sep 2008 18:15:51 +0200
From:	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
To:	Michael Trimarchi <trimarchimichael@...oo.it>
Cc:	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	Andrew Victor <linux@...im.org.za>,
	Anti Sullin <anti.sullin@...ecdesign.ee>
Subject: Re: [PATCH] atmel_serial: update the powersave handler to match
 serial core

Michael Trimarchi <trimarchimichael@...oo.it> wrote:
> > Michael Trimarchi wrote:  
> > > > +    /* we can not wake up if we're running on slow clock */
> > > > +    atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
> > > > +    if (atmel_serial_clk_will_stop())
> > > > +        device_set_wakeup_enable(&pdev->dev, 0);
> > > > +    
> > > This is not true, the wakeup in the slow clock is possible, configure the
> > > input pin of the serial device as a gpio, and wake up on gpio. Then you
> > > must reconfigure as a serial pin, and you can wake up on slow clock.  
> > 
> > Yes, but the current driver doesn't actually support that, does it?
> >   
> 
> Yes I know, but we can think about it and support when is possible
> to wake-up the serial device. Each serial device can change the status
> of the gpio-pin before suspendig and register and handler on it (I think one
> interrupt handler for all the serial that can do that), then reset it after resume.
> I think not all the serial device can do that in the atmel architectures but I suppose
> that can be very usefull for example in gprs application.

I agree it would be useful. It would require changing the port mux
configuration from the driver though, and there's no standardized
interface for doing that. Maybe this is a good motivation to come up
with one?

Btw, I assume the first character you receive will be lost when you do
this, right?

Haavard
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