[PATCH] thermal: re-calculate k_po/k_pu when update sustainable power

[Leo Yan <leo.yan@linaro.org>]

k_po/k_pu are in essence ratio values compared with sustainable power.
So when update sustainable power, we can recalculate k_po/k_pu simply
with below formula:

               sustainable_power(new)
    k_p(new) = ---------------------- * k_p(old)
               sustainable_power(old)

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 drivers/thermal/thermal_core.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d9e525c..212688a 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -908,7 +908,7 @@ sustainable_power_store(struct device *dev, struct device_attribute *devattr,
 			const char *buf, size_t count)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	u32 sustainable_power;
+	u32 sustainable_power, old_val;
 
 	if (!tz->tzp)
 		return -EIO;
@@ -916,8 +916,12 @@ sustainable_power_store(struct device *dev, struct device_attribute *devattr,
 	if (kstrtou32(buf, 10, &sustainable_power))
 		return -EINVAL;
 
+	old_val = tz->tzp->sustainable_power;
+
 	tz->tzp->sustainable_power = sustainable_power;
 
+	tz->tzp->k_po = (tz->tzp->kpo * sustainable_power) / old_val;
+	tz->tzp->k_pu = (tz->tzp->kpu * sustainable_power) / old_val;
 	return count;
 }
 static DEVICE_ATTR(sustainable_power, S_IWUSR | S_IRUGO, sustainable_power_show,
-- 
1.9.1