On Tue, Oct 14, 2014 at 08:53:00AM +0100, Preeti U Murthy wrote:
> We hard code the metrics relevant for cpuidle states in the kernel today.
> Instead pick them up from the device tree so that they remain relevant
> and updated for the system that the kernel is running on.
>
> Cc: linux...@vger.kernel.org
> Cc: Rafael J. Wysocki <r...@rjwysocki.net>
> Cc: devicet...@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: Michael Ellerman <m...@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> Signed-off-by: Preeti U. Murthy <pre...@linux.vnet.ibm.com>
> Signed-off-by: Shreyas B. Prabhu <shre...@linux.vnet.ibm.com>
> ---
>
> drivers/cpuidle/cpuidle-powernv.c | 27 ++++++++++++++++++++++-----
> 1 file changed, 22 insertions(+), 5 deletions(-)
Device tree properties should be documented, and these bindings are
getting very similar to the ones I have just completed for ARM,
I wonder whether we should take the generic bits out of ARM bindings (ie
exit_latency) and make those available to other architectures.
Thanks,
Lorenzo
>
> diff --git a/drivers/cpuidle/cpuidle-powernv.c
> b/drivers/cpuidle/cpuidle-powernv.c
> index fa79392..b57681d 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -165,7 +165,8 @@ static int powernv_add_idle_states(void)
> int nr_idle_states = 1; /* Snooze */
> int dt_idle_states;
> const __be32 *idle_state_flags;
> - u32 len_flags, flags;
> + const __be32 *idle_state_latency;
> + u32 len_flags, flags, latency_ns;
> int i;
>
> /* Currently we have snooze statically defined */
> @@ -182,18 +183,32 @@ static int powernv_add_idle_states(void)
> return nr_idle_states;
> }
>
> + idle_state_latency = of_get_property(power_mgt,
> + "ibm,cpu-idle-state-latencies-ns", NULL);
> + if (!idle_state_latency) {
> + pr_warn("DT-PowerMgmt: missing
> ibm,cpu-idle-state-latencies-ns\n");
> + return nr_idle_states;
> + }
> +
> dt_idle_states = len_flags / sizeof(u32);
>
> for (i = 0; i < dt_idle_states; i++) {
>
> flags = be32_to_cpu(idle_state_flags[i]);
> +
> + /* Cpuidle accepts exit_latency in us and we estimate
> + * target residency to be 10x exit_latency
> + */
> + latency_ns = be32_to_cpu(idle_state_latency[i]);
> if (flags & IDLE_USE_INST_NAP) {
> /* Add NAP state */
> strcpy(powernv_states[nr_idle_states].name, "Nap");
> strcpy(powernv_states[nr_idle_states].desc, "Nap");
> powernv_states[nr_idle_states].flags =
> CPUIDLE_FLAG_TIME_VALID;
> - powernv_states[nr_idle_states].exit_latency = 10;
> - powernv_states[nr_idle_states].target_residency = 100;
> + powernv_states[nr_idle_states].exit_latency =
> + ((unsigned int)latency_ns) / 1000;
> + powernv_states[nr_idle_states].target_residency =
> + ((unsigned int)latency_ns / 100);
> powernv_states[nr_idle_states].enter = &nap_loop;
> nr_idle_states++;
> }
> @@ -204,8 +219,10 @@ static int powernv_add_idle_states(void)
> strcpy(powernv_states[nr_idle_states].desc,
> "FastSleep");
> powernv_states[nr_idle_states].flags =
> CPUIDLE_FLAG_TIME_VALID |
> CPUIDLE_FLAG_TIMER_STOP;
> - powernv_states[nr_idle_states].exit_latency = 300;
> - powernv_states[nr_idle_states].target_residency =
> 1000000;
> + powernv_states[nr_idle_states].exit_latency =
> + ((unsigned int)latency_ns) / 1000;
> + powernv_states[nr_idle_states].target_residency =
> + ((unsigned int)latency_ns / 100);
> powernv_states[nr_idle_states].enter = &fastsleep_loop;
> nr_idle_states++;
> }
>
> --
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