Hi Oliver,

Thanks for reviewing the patch!

On Tue, Nov 01, 2016 at 07:32:58PM +1100, Oliver O'Halloran wrote:

On Thu, Oct 27, 2016 at 7:35 PM, Gautham R. Shenoy
[off-list ref] wrote:

quoted

From: "Gautham R. Shenoy" <redacted>

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 <redacted>
---
 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.

I will change this to use strlcpy as Paul suggested in the reply.

quoted

+       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.

The subsequent patch adds the missing bits to the psscr_val if we are
running on the older firmware. But in any case, as you rightly pointed
out we don't use psscr_table in nap/sleep loops. So this can go.

quoted

+
+       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.

Will clean this up to reflect the state of the code.

quoted

                 * 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?

Ah, good catch! I should be setting target_residency to the default
value only if it is not set by the firmware. Will fix this.

quoted

                        /* 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.

quoted

                        /* 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@gmail.com>

Thanks again!

--
Regards
gautham.