Re: [PATCH] ARM: smp_twd: Reconfigure clockevents after cpufreq change

From: Santosh Shilimkar
Date: Tue May 17 2011 - 10:00:45 EST


On 5/17/2011 4:51 AM, Colin Cross wrote:
The localtimer's clock changes with the cpu clock. After a
cpufreq transition, update the clockevent's frequency and
reprogram the next clock event.

Adds a clock called "smp_twd" that is used to determine the
twd frequency, which can also be used at init time to
avoid calibrating the twd frequency.

Signed-off-by: Colin Cross<ccross@xxxxxxxxxxx>
Cc: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
Cc: Russell King<linux@xxxxxxxxxxxxxxxx>
Cc: Santosh Shilimkar<santosh.shilimkar@xxxxxx>
Cc: Rob Herring<robherring2@xxxxxxxxx>
arch/arm/kernel/smp_twd.c | 69 +++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 66 insertions(+), 3 deletions(-)

This patch depends on Thomas Gleixner's patch to add clockevents_reconfigure

This patch adds a clock that can be used to skip calibration as well
as update the frequency. A later patch (or a later version of this patch)
will drop twd_calibrate_rate once all platforms provide the necessary
smp_twd clock.

Since the "smp_twd" clock node will not have a clk_set_rate()
associated with it, will the clk_get_rate() gives you real
rate. May be we can associate this node as a child of
CPU clock node and use the fixed divider based on peripheral
ratio. Is that the idea here to realize it ?


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