pwm: fan: Add support for always on fan

Why?
In case of continuous governor, the fan-poweron pwm
value is assumed to be at index 1 of pwm values.
In case of tmargin the pwm table would be reversed
(high to low) and hence the assumption is invalid.

How?
While calculating the pwm value in the case of
continuous governor, add a check if the cooling device
is always on fan. If true, for all values of temp,
pwm should be calculated instead of assigning 0.

Bug 200646929

Change-Id: Ibed572fa2af9f8bd36a4a4cbb472029e21aeb442
Signed-off-by: Mantravadi Karthik <mkarthik@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2448826
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

1 files changed, 1 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/thermal/tegra-pwm-fan.txt b/Documentation/devicetree/bindings/thermal/tegra-pwm-fan.txt
index 0ab231b37..42d99abbc 100644
--- a/Documentation/devicetree/bindings/thermal/tegra-pwm-fan.txt
+++ b/Documentation/devicetree/bindings/thermal/tegra-pwm-fan.txt
@@ -44,6 +44,7 @@ Properties details:
   - use_tmargin         : If Tmargin algorithm is being used in therm_fan_est
                           driver. This node needs to be enabled for the pwm fan
                           driver to work properly.
+  - is_always_on        : Enable if the fan is always on.
 
 Example: