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SubjectRe: [patch 2.6.28-rc2] atmel_serial: keep clock off when it's not needed
Date
On Tuesday 28 October 2008, Haavard Skinnemoen wrote:
> David Brownell <david-b@pacbell.net> wrote:
> > From: David Brownell <dbrownell@users.sourceforge.net>
> >
> > The atmel_serial driver is mismanaging its clock by leaving it on
> > at all times ... the whole point of clock management is to leave
> > it off unless it's actively needed, which conserves power!!
> >
> > Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
>
> Hmm...the only remaining clk_enable() is in atmel_serial_pm(). Is that
> really enough?
>
> It looks like the serial core calls ->pm() to power the port up before
> doing anything that might touch the registers, but I can't see that the
> console layer does the same thing...

I verified it on AT91, where the console is normally DBGU and the
other USARTs do get an open().

Didn't verify on AVR32, since 2.6.28-rc can't see the root FS because
of that NOR flash problem. Though I suppose I can try it on an older
kernel.

As a rule the boot loader will be using that USART, and thus will
have enabled its clock. :)

- Dave


>
> Haavard
>
>




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