[PATCH] pmdomain: arm: scmi_pm_domain: Send an explicit request to set the current state

[Sudeep Holla]

On a system with multiple active SCMI agents, one agent(other than OSPM/
Linux or bootloader) would request to turn on a shared power domain
before the Linux boots/initialise the genpds. So when the Linux boots
and gets the power state as already ON, it just registers the genpd with
a default ON state.

However, when the driver that needs this shared power domain is probed
genpd sees that the power domain status is ON and never makes any SCMI
call to power it up which is correct. But, since Linux didn't make an
explicit request to turn on the shared power domain, the SCMI platform
firmware will not know if the OSPM agent is actively using it.

Suppose the other agent that requested the shared power domain to be
powered ON requests to power it OFF as it no longer needs it, the SCMI
platform firmware needs to turn it off if there are no active users of
it which in the above scenaro is the case.

As a result of SCMI platform firmware turning off the resource, OSPM/
Linux will crash the moment as it expects the shared power domain to be
powered ON.

Send an explicit request to set the current state when setting up the
genpd power domains. The other option is to not read the state and set
the genpds as default OFF, but it can't handle the scenario on certain
platforms where SCMI platform keeps all the power domains turned ON by
default for faster boot and expect the OSPM to turn off the unused
domains if power saving is required.

Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 drivers/pmdomain/arm/scmi_pm_domain.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pmdomain/arm/scmi_pm_domain.c b/drivers/pmdomain/arm/scmi_pm_domain.c
index a7784a8bb5db..255c8c36a15c 100644
--- a/drivers/pmdomain/arm/scmi_pm_domain.c
+++ b/drivers/pmdomain/arm/scmi_pm_domain.c
@@ -96,6 +96,8 @@ static int scmi_pm_domain_probe(struct scmi_device *sdev)
 			continue;
 		}

+		power_ops->state_set(ph, i, state);
+
 		scmi_pd->domain = i;
 		scmi_pd->ph = ph;
 		scmi_pd->name = power_ops->name_get(ph, i);
--
2.34.1