Messages in this thread | | | From | David Brownell <> | Subject | Re: [patch 2.6.28-rc2] atmel_serial: keep clock off when it's not needed | Date | Tue, 28 Oct 2008 09:20:19 -0700 |
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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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