thermal: power_allocator: round the division when divvying up power

In situations where there is an uneven number of cooling devices, the
division of power among them can lead to a milliwatt being dropped on
the floor due to rounding errors.  This doesn't sound like a lot, but
some devices only grant the lowest cooling device state for their
maximum power.  So for instance, if the granted_power is the maximum
power and all devices are getting their maximum power, one would get
max_power - 1, making it choose cooling device state 1, instead of 0.

Round the division to make the calculation more accurate.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
index 3ca7530deac622e535f1519df056f843a97f5c2a..4672250b329f4cec54ab243b55b41b127b1c48d0 100644 (file)
--- a/drivers/thermal/power_allocator.c
+++ b/drivers/thermal/power_allocator.c
@@ -196,7 +196,8 @@ static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
        for (i = 0; i < num_actors; i++) {
                u64 req_range = req_power[i] * power_range;
 
-               granted_power[i] = div_u64(req_range, total_req_power);
+               granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range,
+                                                        total_req_power);
 
                if (granted_power[i] > max_power[i]) {
                        extra_power += granted_power[i] - max_power[i];