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

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Date:   Thu, 15 Jun 2023 18:35:53 -0500
From:   Bjorn Andersson <andersson@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     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 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.

Regards,
Bjorn