linux-kernel - Re: [PATCH 1/2] OPP: pstate is only valid for genpd OPP tables

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Date:   Fri, 16 Jun 2023 07:31:41 -0700
From:   Bjorn Andersson <quic_bjorande@...cinc.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
CC:     Bjorn Andersson <andersson@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] OPP: pstate is only valid for genpd OPP tables

On Fri, Jun 16, 2023 at 11:48:30AM +0530, Viresh Kumar wrote:
> On 15-06-23, 18:35, Bjorn Andersson wrote:
> > On Wed, Jun 14, 2023 at 04:07:25PM +0530, Viresh Kumar wrote:
> > > It is not very clear right now that the `pstate` field is only valid for
> > > genpd OPP tables and not consumer tables. And there is no checking for
> > > the same at various places.
> > > 
> > > Add checks in place to verify that and make it clear to the reader.
> > > 
> > > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > > ---
> > >  drivers/opp/core.c    | 18 ++++++++++++++++--
> > >  drivers/opp/debugfs.c |  4 +++-
> > >  drivers/opp/of.c      |  6 ++++++
> > >  3 files changed, 25 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > [..]
> > > @@ -2686,6 +2694,12 @@ int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
> > >  	int dest_pstate = -EINVAL;
> > >  	int i;
> > >  
> > > +	/* Both OPP tables must belong to genpds */
> > > +	if (unlikely(!src_table->is_genpd || !dst_table->is_genpd)) {
> > 
> > I have a platform_device, with a required-opps and with an associated
> > genpd which does not implement set_performance_state(), but its parent
> > genpd does.
> > 
> > This results in me arriving here with src_table of NULL, and boom...
> > 
> > 
> > Looking at the very next statement in this function, it seems arriving
> > here without src_table was valid up until this change.
> 
> Fixed as:
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 48ddd72d2c71..3f46e499d615 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2694,12 +2694,6 @@ int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
>         int dest_pstate = -EINVAL;
>         int i;
> 
> -       /* Both OPP tables must belong to genpds */
> -       if (unlikely(!src_table->is_genpd || !dst_table->is_genpd)) {
> -               pr_err("%s: Performance state is only valid for genpds.\n", __func__);
> -               return -EINVAL;
> -       }
> -
>         /*
>          * Normally the src_table will have the "required_opps" property set to
>          * point to one of the OPPs in the dst_table, but in some cases the
> @@ -2710,6 +2704,12 @@ int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
>         if (!src_table || !src_table->required_opp_count)
>                 return pstate;
> 
> +       /* Both OPP tables must belong to genpds */
> +       if (unlikely(!src_table->is_genpd || !dst_table->is_genpd)) {
> +               pr_err("%s: Performance state is only valid for genpds.\n", __func__);
> +               return -EINVAL;
> +       }
> +
>         /* required-opps not fully initialized yet */
>         if (lazy_linking_pending(src_table))
>                 return -EBUSY;
> 
> Thanks.
> 

Looks good, thanks for the quick response.

Reviewed-by: Bjorn Andersson <quic_bjorande@...cinc.com>
Tested-by: Bjorn Andersson <quic_bjorande@...cinc.com>

Regards,
Bjorn