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 3ca7530..4672250 100644
--- a/drivers/thermal/power_allocator.c
+++ b/drivers/thermal/power_allocator.c
@@ -196,7 +196,8 @@
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];