Let's define the voltatile registers (those that can't be cached) and
enable caching. The rk808 is accessed almost constantly with cpufreq
so this is really nice.
As measured by ftrace:
before this change: cpu0_set_target() => ~2200us
after this change: cpu0_set_target() => ~500us
Signed-off-by: Doug Anderson <dianders at chromium.org>
---
drivers/mfd/rk808.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/drivers/mfd/rk808.c b/drivers/mfd/rk808.c
index 0324422..bd02150 100644
--- a/drivers/mfd/rk808.c
+++ b/drivers/mfd/rk808.c
@@ -29,10 +29,40 @@ struct rk808_reg_data {
int value;
};
+static bool rk808_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+ /*
+ * Notes:
+ * - Technically the ROUND_30s bit makes RTC_CTRL_REG volatile, but
+ * we don't use that feature. It's better to cache.
+ * - It's unlikely we care that RK808_DEVCTRL_REG is volatile since
+ * bits are cleared in case when we shutoff anyway, but better safe.
+ */
+
+ switch (reg) {
+ case RK808_SECONDS_REG ... RK808_WEEKS_REG:
+ case RK808_RTC_STATUS_REG:
+ case RK808_VB_MON_REG:
+ case RK808_THERMAL_REG:
+ case RK808_DCDC_UV_STS_REG:
+ case RK808_LDO_UV_STS_REG:
+ case RK808_DCDC_PG_REG:
+ case RK808_LDO_PG_REG:
+ case RK808_DEVCTRL_REG:
+ case RK808_INT_STS_REG1:
+ case RK808_INT_STS_REG2:
+ return true;
+ }
+
+ return false;
+}
+
static const struct regmap_config rk808_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = RK808_IO_POL_REG,
+ .cache_type = REGCACHE_RBTREE,
+ .volatile_reg = rk808_is_volatile_reg,
};
static struct resource rtc_resources[] = {
--
2.1.0.rc2.206.gedb03e5
