On 13 October 2010 16:14, Amit Kucheria amit.kucheria@linaro.org wrote:
On Wed, Oct 13, 2010 at 4:35 PM, Vincent Guittot vincent.guittot@linaro.org wrote:
Hi,
Exporting the clock tree state is help us to monitor clocks state and to find the guilty clocks. But could it be also possible to have a write access to the clock tree ? During power consumption optimization
That is an interesting idea.
step, we need to identify clock/regulator which should be disable but we also want to know what will be the gain. Instead of waiting for the new code with the right clock management, we generally want to directly disable it and look at the 1st result. It will be also useful when we are looking for the best clock tree configuration without developing/modifying a lot of source code.
Do you anticipate any other interface besides making the 'rate' sysfs file RW and controlling the clock by writing various rates to the file?
So, 0 - clock off any other positive value - round down to the nearest valid rate
and writing to the file would lead to a call to clk.set_rate()
my idea is to export the clock interface through the debugfs for the optimization phase. Then each machine implements and exports the supported function.
For sure, such kind of feature is quite dangerous and must be enable carefully but it would help for optimizing power consumption.
I'm not sure that all clock frameworks are even ready for this feature today, especially if they don't handle recalculation of child clock rates as part of set_rate().
/Amit