linux-kernel - Re: [PATCH v3 6/6] interconnect: Add OPP table support for interconnects

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Message-ID: <CAKfTPtCJFaEfvu3Dnp9WSxQEwSfY=VS+xsoQ+4P+vg7_WL0BAQ@mail.gmail.com>
Date:   Wed, 3 Jul 2019 08:45:21 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Sweeney, Sean" <seansw@....qualcomm.com>,
        daidavid1@...eaurora.org, Rajendra Nayak <rnayak@...eaurora.org>,
        sibis@...eaurora.org, Bjorn Andersson <bjorn.andersson@...aro.org>,
        Evan Green <evgreen@...omium.org>, kernel-team@...roid.com,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 6/6] interconnect: Add OPP table support for interconnects

On Wed, 3 Jul 2019 at 03:10, Saravana Kannan <saravanak@...gle.com> wrote:
>
> Interconnect paths can have different performance points. Now that OPP
> framework supports bandwidth OPP tables, add OPP table support for
> interconnects.
>
> Devices can use the interconnect-opp-table DT property to specify OPP
> tables for interconnect paths. And the driver can obtain the OPP table for
> an interconnect path by calling icc_get_opp_table().

The opp table of a path must come from the aggregation of OPP tables
of the interconnect providers. So such kind of OPP table should be at
provider level but not at path level.

>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---
>  drivers/interconnect/core.c  | 27 ++++++++++++++++++++++++++-
>  include/linux/interconnect.h |  7 +++++++
>  2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
> index 871eb4bc4efc..881bac80bc1e 100644
> --- a/drivers/interconnect/core.c
> +++ b/drivers/interconnect/core.c
> @@ -47,6 +47,7 @@ struct icc_req {
>   */
>  struct icc_path {
>         size_t num_nodes;
> +       struct opp_table *opp_table;
>         struct icc_req reqs[];
>  };
>
> @@ -313,7 +314,7 @@ struct icc_path *of_icc_get(struct device *dev, const char *name)
>  {
>         struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
>         struct icc_node *src_node, *dst_node;
> -       struct device_node *np = NULL;
> +       struct device_node *np = NULL, *opp_node;
>         struct of_phandle_args src_args, dst_args;
>         int idx = 0;
>         int ret;
> @@ -381,10 +382,34 @@ struct icc_path *of_icc_get(struct device *dev, const char *name)
>                 dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
>         mutex_unlock(&icc_lock);
>
> +       opp_node = of_parse_phandle(np, "interconnect-opp-table", idx);
> +       if (opp_node) {
> +               path->opp_table = dev_pm_opp_of_find_table_from_node(opp_node);
> +               of_node_put(opp_node);
> +       }
> +
> +
>         return path;
>  }
>  EXPORT_SYMBOL_GPL(of_icc_get);
>
> +/**
> + * icc_get_opp_table() - Get the OPP table that corresponds to a path
> + * @path: reference to the path returned by icc_get()
> + *
> + * This function will return the OPP table that corresponds to a path handle.
> + * If the interconnect API is disabled, NULL is returned and the consumer
> + * drivers will still build. Drivers are free to handle this specifically, but
> + * they don't have to.
> + *
> + * Return: opp_table pointer on success. NULL is returned when the API is
> + * disabled or the OPP table is missing.
> + */
> +struct opp_table *icc_get_opp_table(struct icc_path *path)
> +{
> +       return path->opp_table;
> +}
> +
>  /**
>   * icc_set_bw() - set bandwidth constraints on an interconnect path
>   * @path: reference to the path returned by icc_get()
> diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h
> index dc25864755ba..0c0bc55f0e89 100644
> --- a/include/linux/interconnect.h
> +++ b/include/linux/interconnect.h
> @@ -9,6 +9,7 @@
>
>  #include <linux/mutex.h>
>  #include <linux/types.h>
> +#include <linux/pm_opp.h>
>
>  /* macros for converting to icc units */
>  #define Bps_to_icc(x)  ((x) / 1000)
> @@ -28,6 +29,7 @@ struct device;
>  struct icc_path *icc_get(struct device *dev, const int src_id,
>                          const int dst_id);
>  struct icc_path *of_icc_get(struct device *dev, const char *name);
> +struct opp_table *icc_get_opp_table(struct icc_path *path);
>  void icc_put(struct icc_path *path);
>  int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw);
>
> @@ -49,6 +51,11 @@ static inline void icc_put(struct icc_path *path)
>  {
>  }
>
> +static inline struct opp_table *icc_get_opp_table(struct icc_path *path)
> +{
> +       return NULL;
> +}
> +
>  static inline int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
>  {
>         return 0;
> --
> 2.22.0.410.gd8fdbe21b5-goog
>