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Message-ID: <e6fc06eb-fe52-4cb3-b412-a602369ee875@leemhuis.info>
Date: Thu, 9 May 2024 14:35:05 +0200
From: Thorsten Leemhuis <regressions@...mhuis.info>
To: Viresh Kumar <viresh.kumar@...aro.org>, Viresh Kumar
<vireshk@...nel.org>, Nishanth Menon <nm@...com>,
Stephen Boyd <sboyd@...nel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
"Rafael J. Wysocki" <rafael@...nel.org>
Cc: linux-pm@...r.kernel.org, Vincent Guittot <vincent.guittot@...aro.org>,
Vladimir Lypak <vladimir.lypak@...il.com>, linux-kernel@...r.kernel.org,
Linux kernel regressions list <regressions@...ts.linux.dev>
Subject: Re: [PATCH V2] OPP: Fix required_opp_tables for multiple genpds using
same table
On 12.04.24 08:41, Viresh Kumar wrote:
> The required_opp_tables parsing is not perfect, as the OPP core does the
> parsing solely based on the DT node pointers.
>
> The core sets the required_opp_tables entry to the first OPP table in
> the "opp_tables" list, that matches with the node pointer.
>
> If the target DT OPP table is used by multiple devices and they all
> create separate instances of 'struct opp_table' from it, then it is
> possible that the required_opp_tables entry may be set to the incorrect
> sibling device.
>
> Unfortunately, there is no clear way to initialize the right values
> during the initial parsing and we need to do this at a later point of
> time.
>
> Cross check the OPP table again while the genpds are attached and fix
> them if required.
>
> Also add a new API for the genpd core to fetch the device pointer for
> the genpd.
>
> Cc: Thorsten Leemhuis <regressions@...mhuis.info>
> Reported-by: Vladimir Lypak <vladimir.lypak@...il.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218682
Did this fall through the cracks? Just wondering, as from here it looks
like for about four weeks now nothing happened to fix the regression
linked above. But I might have missed something. Or is everybody waiting
for a test from the reporter?
Ciao, Thorsten
> Co-developed-by: Vladimir Lypak <vladimir.lypak@...il.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> V2:
> - Fix an `if` condition.
> - s/Bugzilla/Closes/ and change ordering.
>
> drivers/opp/core.c | 31 ++++++++++++++++++++++++++++++-
> drivers/pmdomain/core.c | 10 ++++++++++
> include/linux/pm_domain.h | 6 ++++++
> 3 files changed, 46 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index e233734b7220..cb4611fe1b5b 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2394,7 +2394,8 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
> static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
> const char * const *names, struct device ***virt_devs)
> {
> - struct device *virt_dev;
> + struct device *virt_dev, *gdev;
> + struct opp_table *genpd_table;
> int index = 0, ret = -EINVAL;
> const char * const *name = names;
>
> @@ -2427,6 +2428,34 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
> goto err;
> }
>
> + /*
> + * The required_opp_tables parsing is not perfect, as the OPP
> + * core does the parsing solely based on the DT node pointers.
> + * The core sets the required_opp_tables entry to the first OPP
> + * table in the "opp_tables" list, that matches with the node
> + * pointer.
> + *
> + * If the target DT OPP table is used by multiple devices and
> + * they all create separate instances of 'struct opp_table' from
> + * it, then it is possible that the required_opp_tables entry
> + * may be set to the incorrect sibling device.
> + *
> + * Cross check it again and fix if required.
> + */
> + gdev = dev_to_genpd_dev(virt_dev);
> + if (IS_ERR(gdev))
> + return PTR_ERR(gdev);
> +
> + genpd_table = _find_opp_table(gdev);
> + if (!IS_ERR(genpd_table)) {
> + if (genpd_table != opp_table->required_opp_tables[index]) {
> + dev_pm_opp_put_opp_table(opp_table->required_opp_tables[index]);
> + opp_table->required_opp_tables[index] = genpd_table;
> + } else {
> + dev_pm_opp_put_opp_table(genpd_table);
> + }
> + }
> +
> /*
> * Add the virtual genpd device as a user of the OPP table, so
> * we can call dev_pm_opp_set_opp() on it directly.
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 4215ffd9b11c..c40eda92a85a 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -184,6 +184,16 @@ static struct generic_pm_domain *dev_to_genpd(struct device *dev)
> return pd_to_genpd(dev->pm_domain);
> }
>
> +struct device *dev_to_genpd_dev(struct device *dev)
> +{
> + struct generic_pm_domain *genpd = dev_to_genpd(dev);
> +
> + if (IS_ERR(genpd))
> + return ERR_CAST(genpd);
> +
> + return &genpd->dev;
> +}
> +
> static int genpd_stop_dev(const struct generic_pm_domain *genpd,
> struct device *dev)
> {
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 772d3280d35f..f24546a3d3db 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -260,6 +260,7 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
> int pm_genpd_init(struct generic_pm_domain *genpd,
> struct dev_power_governor *gov, bool is_off);
> int pm_genpd_remove(struct generic_pm_domain *genpd);
> +struct device *dev_to_genpd_dev(struct device *dev);
> int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state);
> int dev_pm_genpd_add_notifier(struct device *dev, struct notifier_block *nb);
> int dev_pm_genpd_remove_notifier(struct device *dev);
> @@ -307,6 +308,11 @@ static inline int pm_genpd_remove(struct generic_pm_domain *genpd)
> return -EOPNOTSUPP;
> }
>
> +static inline struct device *dev_to_genpd_dev(struct device *dev)
> +{
> + return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> static inline int dev_pm_genpd_set_performance_state(struct device *dev,
> unsigned int state)
> {
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