OPP: Use _set_opp_level() for single genpd case

There are two genpd (as required-opp) cases that we need to handle,
devices with a single genpd and ones with multiple genpds.

The multiple genpds case is clear, where the OPP core calls
dev_pm_domain_attach_by_name() for them and uses the virtual devices
returned by this helper to call dev_pm_domain_set_performance_state()
later to change the performance state.

The single genpd case however requires special handling as we need to
use the same `dev` structure (instead of a virtual one provided by genpd
core) for setting the performance state via
dev_pm_domain_set_performance_state().

As we move towards more generic code to take care of the required OPPs,
where we will recursively call dev_pm_opp_set_opp() for all the required
OPPs, the above special case becomes a problem.

It doesn't make sense for a device's DT entry to have both "opp-level"
and single "required-opps" entry pointing to a genpd's OPP, as that
would make the OPP core call dev_pm_domain_set_performance_state() for
two different values for the same device structure. And so we can reuse
the 'opp->level" field in such a case and call _set_opp_level() for the
device.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index f2e2aa07b431..aeb216f7e978 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1088,10 +1088,12 @@ static int _opp_set_required_opps_generic(struct device *dev,
 static int _opp_set_required_opps_genpd(struct device *dev,
 	struct opp_table *opp_table, struct dev_pm_opp *opp, bool scaling_down)
 {
-	struct device **genpd_virt_devs =
-		opp_table->genpd_virt_devs ? opp_table->genpd_virt_devs : &dev;
+	struct device **genpd_virt_devs = opp_table->genpd_virt_devs;
 	int index, target, delta, ret;
 
+	if (!genpd_virt_devs)
+		return 0;
+
 	/* Scaling up? Set required OPPs in normal order, else reverse */
 	if (!scaling_down) {
 		index = 0;