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SubjectRe: [PATCH v2 1/4] OPP: Allow required-opps even if the device doesn't have power-domains
On Tue, Jul 16, 2019 at 10:18 AM Sibi Sankar <sibis@codeaurora.org> wrote:
>
> Hey Saravana,
> Thanks for taking time to post out this series.
>
> On 6/26/19 3:03 AM, Saravana Kannan wrote:
> > A Device-A can have a (minimum) performance requirement on another
> > Device-B to be able to function correctly. This performance requirement
> > on Device-B can also change based on the current performance level of
> > Device-A.
> >
> > The existing required-opps feature fits well to describe this need. So,
> > instead of limiting required-opps to point to only PM-domain devices,
> > allow it to point to any device.
> >
> > Signed-off-by: Saravana Kannan <saravanak@google.com>
> > ---
> > drivers/opp/core.c | 2 +-
> > drivers/opp/of.c | 14 --------------
> > 2 files changed, 1 insertion(+), 15 deletions(-)
> >
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index 0e7703fe733f..74c7bdc6f463 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -710,7 +710,7 @@ static int _set_required_opps(struct device *dev,
> > return 0;
> >
> > /* Single genpd case */
> > - if (!genpd_virt_devs) {
> > + if (!genpd_virt_devs && required_opp_tables[0]->is_genpd) {
> https://patchwork.kernel.org/patch/10940671/
> This was already removed as a part of ^^ and is in linux-next.

Thanks for the heads up.

>
> > pstate = opp->required_opps[0]->pstate;
> > ret = dev_pm_genpd_set_performance_state(dev, pstate);
> > if (ret) {
> > diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> > index c10c782d15aa..7c8336e94aff 100644
> > --- a/drivers/opp/of.c
> > +++ b/drivers/opp/of.c
> > @@ -195,9 +195,6 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
> > */
> > count_pd = of_count_phandle_with_args(dev->of_node, "power-domains",
> > "#power-domain-cells");
> > - if (!count_pd)
> > - goto put_np;
> > -
> > if (count_pd > 1) {
> > genpd_virt_devs = kcalloc(count, sizeof(*genpd_virt_devs),
> > GFP_KERNEL);
> > @@ -226,17 +223,6 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
> >
> > if (IS_ERR(required_opp_tables[i]))
> > goto free_required_tables;
> > -
> > - /*
> > - * We only support genpd's OPPs in the "required-opps" for now,
> > - * as we don't know how much about other cases. Error out if the
> > - * required OPP doesn't belong to a genpd.
> > - */
> > - if (!required_opp_tables[i]->is_genpd) {
> > - dev_err(dev, "required-opp doesn't belong to genpd: %pOF\n",
> > - required_np);
> > - goto free_required_tables;
> > - }
>
> I expect the series to not work as is in its current state since I
> see a circular dependency here. The required-opp tables of the parent
> devfreq won't be populated until we add the opp-table of the child
> devfreq node while the child devfreq using passive governor would
> return -EPROBE_DEFER until the parent devfreq probes.

I looked into this when I wrote the patches. I thought I handled it
correctly. Let me take another look.

-Saravana

> The same applies to this patch -> https://patchwork.kernel.org/patch
> /11046147/ I posted out based on your series. So we would probably have
> to address the dependency here.
>
> > }
> >
> > goto put_np;
> >
>
> --
> Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc, is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

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