* Ran Shalit <ranshalit@xxxxxxxxx> [151125 11:49]:
> On Wed, Nov 25, 2015 at 8:50 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
>
> We actually want the deeper state, but not in the price of performance...
> So I thought of these possibilities:
> 1. configure the sleep state to check activity for a longer time than
> micro seconds (several seconds). If there is non activity in that long
> period, only than will move to retention. I am not sure if there is
> such configuration parameter . Maybe one of the following parameters
> can be configured for this option ?
>
> 46 struct cpuidle_params {
> 47 u32 exit_latency; /* exit_latency = sleep + wake-up
> latencies */
> 48 u32 target_residency;
> 49 u8 valid; /* validates the C-state */
> 50 };
>
> 2. Another option can be to write a kernel module which check if there
> is ethernet activity for X seconds, if there is none - it will enable
> power management , otherwise - it will disable the power management.
It really should be implemented with the standard pm_runtime calls in the
Ethernet driver. Maybe you can clk_get some parent clock from the Ethernet
driver that will block the idle state?
> These maybe can solve the ethernet issue, but I still not sure why
> there is constantly incrementation in the retention state, as if it
> enter and leave the state all periodically. Is it becuase some
> task/thread/process in the system (I guess it can be a kernel process
> actually) ?
I think what you're seeing is the kernel idle code incrementing it
every time the SoC hits idle.
Regards,
Tony
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