18.01.2021 13:59, Ulf Hansson пишет:

On Mon, 18 Jan 2021 at 08:28, Viresh Kumar [off-list ref] wrote:

quoted

On 18-01-21, 04:13, Dmitry Osipenko wrote:

quoted

Make set_performance_state() callback optional in order to remove the
need from power domain drivers to implement a dummy callback. If callback
isn't implemented by a GENPD driver, then the performance state is passed
to the parent domain.

Tested-by: Peter Geis <redacted>
Tested-by: Nicolas Chauvet <redacted>
Tested-by: Matt Merhar <redacted>
Suggested-by: Ulf Hansson <redacted>
Reviewed-by: Ulf Hansson <redacted>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/base/power/domain.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 9a14eedacb92..a3e1bfc233d4 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c

@@ -339,9 +339,11 @@ static int _genpd_set_performance_state(struct generic_pm_domain *genpd,
                      goto err;
      }

-     ret = genpd->set_performance_state(genpd, state);
-     if (ret)
-             goto err;
+     if (genpd->set_performance_state) {
+             ret = genpd->set_performance_state(genpd, state);
+             if (ret)
+                     goto err;
+     }

Earlier in this routine we also have this:

if (!parent->set_performance_state)
        continue;

Should we change that too ?

Good point! I certainly overlooked that when reviewing. We need to
reevaluate the new state when propagating to the parent(s).

To me, it looks like when doing the propagation we must check if the
parent has the ->set_performance_state() callback assigned. If so, we
should call dev_pm_opp_xlate_performance_state(), but otherwise just
use the value of "state", when doing the reevaluation.

Does it make sense?

I played a tad with the power domains by creating a couple dummy domains
and putting them into a parent->child chain. Yours suggestion works well
for the case where intermediate domain doesn't implement the
set_performance_state() callback, i.e. the performance state is
propagated through the whole chain instead of stopping on the domain
that doesn't implement the callback.

I'll make a v4, thanks.