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Subject[PATCH v4 21/24] PM / devfreq: tegra30: Synchronize average count on target's update
Date
The average count may get out of sync if interrupt was disabled / avoided
for a long time due to upper watermark optimization, hence it should be
re-synced on each target's update to ensure that watermarks are set up
correctly on EMC rate-change notification and that a correct frequency
is selected for device.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/devfreq/tegra30-devfreq.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index 4d582809acb6..8a674fad26be 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -466,11 +466,41 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
dev->boost_freq, cpufreq_get(0));
}

+static void tegra_devfreq_sync_avg_count(struct tegra_devfreq *tegra,
+ struct tegra_devfreq_device *dev)
+{
+ u32 avg_count, avg_freq, old_upper, new_upper;
+
+ avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
+ avg_freq = avg_count / ACTMON_SAMPLING_PERIOD;
+
+ old_upper = tegra_actmon_upper_freq(tegra, dev->avg_freq);
+ new_upper = tegra_actmon_upper_freq(tegra, avg_freq);
+
+ /* similar to ISR, see comments in actmon_isr_device() */
+ if (old_upper != new_upper) {
+ dev->avg_freq = avg_freq;
+ dev->boost_freq = 0;
+ }
+}
+
static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
struct tegra_devfreq_device *dev)
{
unsigned long target_freq;

+ /*
+ * The avg_count / avg_freq is getting snapshoted on device's
+ * interrupt, but there are cases where actual value need to
+ * be utilized on target's update, like CPUFreq boosting and
+ * overriding the min freq via /sys/class/devfreq/devfreq0/min_freq
+ * because we're optimizing the upper watermark based on the
+ * actual EMC frequency. This means that interrupt may be
+ * inactive for a long time and thus making snapshoted value
+ * outdated.
+ */
+ tegra_devfreq_sync_avg_count(tegra, dev);
+
target_freq = min(dev->avg_freq + dev->boost_freq, KHZ_MAX);
target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);

--
2.22.0
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