Re: [PATCH V3 3/3] OPP: Don't set OPP recursively for a parent genpd

From: Ulf Hansson
Date: Wed Nov 22 2023 - 09:27:16 EST


On Thu, 16 Nov 2023 at 11:43, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>
> Like other frameworks (clk, regulator, etc.) genpd core too takes care
> of propagation to performance state to parent genpds. The OPP core
> shouldn't attempt the same, or it may result in undefined behavior.
>
> Add checks at various places to take care of the same.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>

I think this looks good to me, even if I think it's a bit tricky to
consider the various scenarios. :-) Feel free to add:

Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

Kind regards
Uffe

> ---
> drivers/opp/core.c | 16 +++++++++++++++-
> drivers/opp/of.c | 7 +++++--
> 2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index e08375ed50aa..4f1ca84d9ed0 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2392,6 +2392,12 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
> return -EINVAL;
> }
>
> + /* Genpd core takes care of propagation to parent genpd */
> + if (opp_table->is_genpd) {
> + dev_err(dev, "%s: Operation not supported for genpds\n", __func__);
> + return -EOPNOTSUPP;
> + }
> +
> /* Checking only the first one is enough ? */
> if (opp_table->required_devs[0])
> return 0;
> @@ -2453,8 +2459,16 @@ static int _opp_set_required_devs(struct opp_table *opp_table,
> if (opp_table->required_devs[0])
> return 0;
>
> - for (i = 0; i < opp_table->required_opp_count; i++)
> + for (i = 0; i < opp_table->required_opp_count; i++) {
> + /* Genpd core takes care of propagation to parent genpd */
> + if (required_devs[i] && opp_table->is_genpd &&
> + opp_table->required_opp_tables[i]->is_genpd) {
> + dev_err(dev, "%s: Operation not supported for genpds\n", __func__);
> + return -EOPNOTSUPP;
> + }
> +
> opp_table->required_devs[i] = required_devs[i];
> + }
>
> return 0;
> }
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index 5a7e294e56b7..f9f0b22bccbb 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -339,8 +339,11 @@ static int _link_required_opps(struct dev_pm_opp *opp, struct opp_table *opp_tab
> */
> if (required_table->is_genpd && opp_table->required_opp_count == 1 &&
> !opp_table->required_devs[0]) {
> - if (!WARN_ON(opp->level != OPP_LEVEL_UNSET))
> - opp->level = opp->required_opps[0]->level;
> + /* Genpd core takes care of propagation to parent genpd */
> + if (!opp_table->is_genpd) {
> + if (!WARN_ON(opp->level != OPP_LEVEL_UNSET))
> + opp->level = opp->required_opps[0]->level;
> + }
> }
>
> return 0;
> --
> 2.31.1.272.g89b43f80a514
>