Re: [PATCH] ARM: twd: Adjust localtimer frequency with cpufreq notifiers
From: Rob Herring
Date: Fri Mar 04 2011 - 15:31:26 EST
On 03/04/2011 02:11 PM, Colin Cross wrote:
On Fri, Mar 4, 2011 at 2:27 AM, martin persson
<martin.persson@xxxxxxxxxxxxxx> wrote:
We've seen no problems using this patch and have been grateful for it's
existence. So I'm happy to put:
Tested-by: martin.persson@xxxxxxxxxxxxxx
/Martin
On 03/04/2011 11:17 AM, Linus Walleij wrote:
2010/11/18 Colin Cross<ccross@xxxxxxxxxxx>:
The clock to the ARM TWD local timer scales with the cpu
frequency. To allow the cpu frequency to change while
maintaining a constant TWD frequency, pick a lower target
frequency for the TWD and use the prescaler to divide down
to the closest lower frequency.
We are using this with some custom hooks for the U8500.
Tested-by: Linus Walleij<linus.walleij@xxxxxxxxxx>
Martin Persson can probably provide an additional Tested-by
from ST-Ericsson if it helps.
Colin are you merging this patch for 2.6.39 through
Russells tracker or pull request? It's an important patch
for us.
Yours,
Linus Walleij
I never got any responses, and it conflicts with Rob Herring's patch
6434/1, although that has not been applied. Russell, do you want this
in the patch tracker?
Russell wanted to move over completely to using the clock api rather
than making clock api usage optional and this was dependent on his
init_early changes for Realview/Versatile. So I need to update the
patches based on that.
I think a cleaner solution for this is platforms should define a clock
for the local timer and the notifier can just get the clock rate again.
But these clocks have to be implemented first on all platforms using
local timer to make it unconditional, and I don't have the clock tree
knowledge of all those platforms.
Rob
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