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Date: Tue, 1 Nov 2016 19:32:58 +1100
From: "Oliver O'Halloran" <oohall@...il.com>
To: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Michael Neuling <mikey@...ling.org>,
Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
"Shreyas B. Prabhu" <shreyasbp@...il.com>,
Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
Stewart Smith <stewart@...ux.vnet.ibm.com>,
Balbir Singh <bsingharora@...il.com>,
skiboot list <skiboot@...ts.ozlabs.org>,
linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 2/3] cpuidle:powernv: Add helper function to populate
powernv idle states.
On Thu, Oct 27, 2016 at 7:35 PM, Gautham R. Shenoy
<ego@...ux.vnet.ibm.com> wrote:
> From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
>
> In the current code for powernv_add_idle_states, there is a lot of code
> duplication while initializing an idle state in powernv_states table.
>
> Add an inline helper function to populate the powernv_states[] table for
> a given idle state. Invoke this for populating the "Nap", "Fastsleep"
> and the stop states in powernv_add_idle_states.
>
> Signed-off-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>
> ---
> drivers/cpuidle/cpuidle-powernv.c | 82 +++++++++++++++++++++++----------------
> include/linux/cpuidle.h | 1 +
> 2 files changed, 49 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
> index 7fe442c..11b22b9 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -167,6 +167,28 @@ static int powernv_cpuidle_driver_init(void)
> return 0;
> }
>
> +static inline void add_powernv_state(int index, const char *name,
> + unsigned int flags,
> + int (*idle_fn)(struct cpuidle_device *,
> + struct cpuidle_driver *,
> + int),
> + unsigned int target_residency,
> + unsigned int exit_latency,
> + u64 psscr_val)
> +{
> + strncpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
> + strncpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
If the supplied name is equal to CPUIDLE_NAME_LEN then strncpy() won't
terminate the string. The least annoying fix is to memset() the whole
structure to zero and set n to CPUIDLE_NAME_LEN - 1.
> + powernv_states[index].flags = flags;
> + powernv_states[index].target_residency = target_residency;
> + powernv_states[index].exit_latency = exit_latency;
> + powernv_states[index].enter = idle_fn;
> +
> + if (idle_fn != stop_loop)
> + return;
This can probably be deleted. The nap/sleep loops don't look at the
psscr setting and you've passed in a dummy value of zero anyway.
> +
> + stop_psscr_table[index] = psscr_val;
> +}
> +
> static int powernv_add_idle_states(void)
> {
> struct device_node *power_mgt;
> @@ -236,6 +258,7 @@ static int powernv_add_idle_states(void)
> "ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);
>
> for (i = 0; i < dt_idle_states; i++) {
> + unsigned int exit_latency, target_residency;
> /*
> * If an idle state has exit latency beyond
> * POWERNV_THRESHOLD_LATENCY_NS then don't use it
> @@ -244,27 +267,30 @@ static int powernv_add_idle_states(void)
> if (latency_ns[i] > POWERNV_THRESHOLD_LATENCY_NS)
> continue;
>
> + exit_latency = ((unsigned int)latency_ns[i]) / 1000;
> + target_residency = (!rc) ? ((unsigned int)residency_ns[i]) : 0;
> + /*
> + * Firmware passes residency values in ns.
> + * cpuidle expects it in us.
> + */
> + target_residency /= 1000;
> +
> /*
> * Cpuidle accepts exit_latency and target_residency in us.
This comment says the same thing as the one above.
> * Use default target_residency values if f/w does not expose it.
> */
> if (flags[i] & OPAL_PM_NAP_ENABLED) {
> + target_residency = 100;
Hmm, the above comment says that we should only use the default value
for target_residency if firmware hasn't provided a value. Is there a
reason we always use the hard coded value?
> /* 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 = 0;
> - powernv_states[nr_idle_states].target_residency = 100;
> - powernv_states[nr_idle_states].enter = nap_loop;
> + add_powernv_state(nr_idle_states, "Nap",
> + CPUIDLE_FLAG_NONE, nap_loop,
> + target_residency, exit_latency, 0);
> } 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];
> + add_powernv_state(nr_idle_states, names[i],
> + CPUIDLE_FLAG_NONE, stop_loop,
> + target_residency, exit_latency,
> + psscr_val[i]);
> }
>
> /*
> @@ -274,32 +300,20 @@ static int powernv_add_idle_states(void)
> #ifdef CONFIG_TICK_ONESHOT
> if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
> flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
> + target_residency = 300000;
Same comment as above.
> /* Add FASTSLEEP state */
> - strcpy(powernv_states[nr_idle_states].name, "FastSleep");
> - strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
> - 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;
> + add_powernv_state(nr_idle_states, "FastSleep",
> + CPUIDLE_FLAG_TIMER_STOP,
> + fastsleep_loop,
> + target_residency, exit_latency, 0);
> } 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];
> + add_powernv_state(nr_idle_states, names[i],
> + CPUIDLE_FLAG_TIMER_STOP, stop_loop,
> + target_residency, exit_latency,
> + psscr_val[i]);
> }
> #endif
> - powernv_states[nr_idle_states].exit_latency =
> - ((unsigned int)latency_ns[i]) / 1000;
> -
> - if (!rc) {
> - powernv_states[nr_idle_states].target_residency =
> - ((unsigned int)residency_ns[i]) / 1000;
> - }
> -
> nr_idle_states++;
> }
> out:
> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index bb31373..c4e10f8 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -62,6 +62,7 @@ struct cpuidle_state {
> };
>
> /* Idle State Flags */
> +#define CPUIDLE_FLAG_NONE (0x00)
> #define CPUIDLE_FLAG_COUPLED (0x02) /* state applies to multiple cpus */
> #define CPUIDLE_FLAG_TIMER_STOP (0x04) /* timer is stopped on this state */
>
> --
> 1.9.4
>
Looks good otherwise.
Reviewed-by: Oliver O'Halloran <oohall@...il.com>
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