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

Benjamin Herrenschmidt
2016-06-13T21:48:56Z

On Wed, 2016-06-08 at 11:54 -0500, Shreyas B. Prabhu wrote:
>
>  /*
>   * States for dedicated partition case.
>   */
> @@ -167,6 +183,8 @@ static int powernv_add_idle_states(void)
>   int nr_idle_states = 1; /* Snooze */
>   int dt_idle_states;
>   u32 *latency_ns, *residency_ns, *flags;
> + u64 *psscr_val = NULL;
> + const char *names[CPUIDLE_STATE_MAX];
>   int i, rc;
>
>   /* Currently we have snooze statically defined */
> @@ -199,12 +217,41 @@ static int powernv_add_idle_states(void)
>   goto out_free_latency;
>   }
>
> + rc = of_property_read_string_array(power_mgt,
> +    "ibm,cpu-idle-state-names", names,
> +    dt_idle_states);

Ok so from this I assume that dt_idle_states is the number of entries,
which has been checked properly to be < CPUIDLE_STATE_MAX correct ?

Beause ...

> + 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);
> + rc = of_property_read_u64_array(power_mgt,
> + "ibm,cpu-idle-state-psscr",
> + psscr_val, dt_idle_states);

Here, psscr val is only one u64 ... shouldn't you kmalloc sizeof(..) *
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);

Just like we do here

>   rc = of_property_read_u32_array(power_mgt,  "ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);
>   for (i = 0; i < dt_idle_states; i++) {
> -
> + /*
> +  * If an idle state has exit latency beyond
> +  * POWERNV_THRESHOLD_LATENCY_NS then don't use it
> +  * in cpu-idle.
> +  */
> + if (latency_ns[i] > POWERNV_THRESHOLD_LATENCY_NS)
> + continue;
>   /*
>    * Cpuidle accepts exit_latency and target_residency in us.
>    * Use default target_residency values if f/w does not expose it.
> @@ -216,6 +263,16 @@ static int powernv_add_idle_states(void)
>   powernv_states[nr_idle_states].flags = 0;
>   powernv_states[nr_idle_states].target_residency = 100;
>   powernv_states[nr_idle_states].enter = &nap_loop;
> + } else if ((flags[i] & OPAL_PM_STOP_INST_FAST) &&
> + !(flags[i] & OPAL_PM_TIMEBASE_STOP)) {
> + strncpy(powernv_states[nr_idle_states].name,
> + names[i], CPUIDLE_NAME_LEN);
> + strncpy(powernv_states[nr_idle_states].desc,
> + names[i], CPUIDLE_NAME_LEN);
> + powernv_states[nr_idle_states].flags = 0;
> +
> + powernv_states[nr_idle_states].enter = stop_loop;
> + stop_psscr_table[nr_idle_states] = psscr_val[i];
>   }
>
>   /*
> @@ -231,6 +288,16 @@ static int powernv_add_idle_states(void)
>   powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
>   powernv_states[nr_idle_states].target_residency = 300000;
>   powernv_states[nr_idle_states].enter = &fastsleep_loop;
> + } else if ((flags[i] & OPAL_PM_STOP_INST_DEEP) &&
> + (flags[i] & OPAL_PM_TIMEBASE_STOP)) {
> + strncpy(powernv_states[nr_idle_states].name,
> + names[i], CPUIDLE_NAME_LEN);
> + strncpy(powernv_states[nr_idle_states].desc,
> + names[i], CPUIDLE_NAME_LEN);
> +
> + powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
> + powernv_states[nr_idle_states].enter = stop_loop;
> + stop_psscr_table[nr_idle_states] = psscr_val[i];
>   }
>  #endif
>   powernv_states[nr_idle_states].exit_latency =
> @@ -245,6 +312,8 @@ static int powernv_add_idle_states(void)
>   }
>
>   kfree(residency_ns);
> +out_free_psscr:
> + kfree(psscr_val);
>  out_free_latency:
>   kfree(latency_ns);