Re: [PATCH v6 10/11] cpuidle/powernv: Add support for POWER ISA v3 idle states

Daniel Lezcano
2016-06-13T15:34:51Z

On Wed, Jun 08, 2016 at 11:54:30AM -0500, Shreyas B. Prabhu wrote:
> POWER ISA v3 defines a new idle processor core mechanism. In summary,
> a) new instruction named stop is added.
> b) new per thread SPR named PSSCR is added which controls the behavior
> of stop instruction.
>
> Supported idle states and value to be written to PSSCR register to enter
> any idle state is exposed via ibm,cpu-idle-state-names and
> ibm,cpu-idle-state-psscr respectively. To enter an idle state,
> platform provided power_stop() needs to be invoked with the appropriate
> PSSCR value.
>
> This patch adds support for this new mechanism in cpuidle powernv driver.
>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
> Cc: linux-pm@vger.kernel.org
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Paul Mackerras <paulus@ozlabs.org>
> Cc: linuxppc-dev@lists.ozlabs.org
> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
> ---

[ ... ]

> + rc = of_property_read_string_array(power_mgt,
> + "ibm,cpu-idle-state-names", names,
> + dt_idle_states);
> + if (rc < 0) {
> + pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-names in DT\n");
> + goto out_free_latency;
> + }
> +
> + /*
> + * If the idle states use stop instruction, probe for psscr values
> + * which are necessary to specify required stop level.
> + */
> + if (flags[0] & (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP)) {
> + psscr_val = kcalloc(dt_idle_states, sizeof(*psscr_val),
> + GFP_KERNEL);

if (!psscr_val) check missing.

> + rc = of_property_read_u64_array(power_mgt,
> + "ibm,cpu-idle-state-psscr",
> + psscr_val, dt_idle_states);
> + if (rc) {
> + pr_warn("cpuidle-powernv: missing ibm,cpu-idle-states-psscr in DT\n");
> + goto out_free_psscr;
> + }
> + }
> residency_ns = kzalloc(sizeof(*residency_ns) * dt_idle_states, GFP_KERNEL);

if (!residency_ns) check missing.

I suppose the code is relying on 'of_property_read_u32_array' to check it,
right ?

-- Daniel