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From: Chanwoo Choi <cwchoi00@gmail.com>
To: Saravana Kannan <saravanak@google.com>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
	Stephen Boyd <sboyd@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	kernel-team@android.com, Linux PM list <linux-pm@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 3/3] PM / devfreq: Add required OPPs support to passive governor
Date: Sat, 22 Jun 2019 21:00:59 +0900
Message-ID: <CAGTfZH1COWzhDBr63S18md44ypKixstHHsX7cm5LnAhXXbfecA@mail.gmail.com> (raw)
In-Reply-To: <20190622003449.33707-4-saravanak@google.com>

Hi,

Absolutely, I agree this approach.
But, I add some comments on below. please check them.

2019년 6월 22일 (토) 오전 9:36, Saravana Kannan <saravanak@google.com>님이 작성:
>
> Look at the required OPPs of the "parent" device to determine the OPP that
> is required from the slave device managed by the passive governor. This
> allows having mappings between a parent device and a slave device even when
> they don't have the same number of OPPs.
>
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/devfreq/governor_passive.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 3bc29acbd54e..bd4a98bb15b1 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -21,8 +21,9 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>         struct devfreq_passive_data *p_data
>                         = (struct devfreq_passive_data *)devfreq->data;
>         struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
> +       struct opp_table *opp_table = NULL, *c_opp_table = NULL;

In this function, the base device is passive devfreq device.
So, I think that better to define the 'parent_opp_table' instead of 'opp_table'
indicating the OPP table of parent devfreq device. And better to define
just 'opp_table' instead of 'c_opp_table' indicating the passive devfreq device.
- opp_table -> parent_opp_table
- c_opp_table -> opp_table

>         unsigned long child_freq = ULONG_MAX;
> -       struct dev_pm_opp *opp;
> +       struct dev_pm_opp *opp = NULL, *c_opp = NULL;

Ditto. I think that better to define the variables as following:
- opp -> parent_opp
- c_cpp -> opp

>         int i, count, ret = 0;
>
>         /*
> @@ -65,7 +66,20 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>                 goto out;
>         }
>
> -       dev_pm_opp_put(opp);
> +       opp_table = dev_pm_opp_get_opp_table(parent_devfreq->dev.parent);

devfreq_passive_get_target_freq() is called frequently for DVFS support.
I think that you have to add 'struct opp_table *opp_table' instance to
'struct devfreq'
and then get 'opp_table' instance in the devfreq_add_device().

devfreq_add_device() already get the OPP information by using
dev_pm_opp_get_suspend_opp_freq().
You can add following code nearby dev_pm_opp_get_suspend_opp_freq() in
devfreq_add_device().
- devfreq->opp_table = dev_pm_opp_get_opp_table(dev);


> +       if (IS_ERR_OR_NULL(opp_table)) {
> +               ret = PTR_ERR(opp_table);
> +               goto out;
> +       }
> +
> +       c_opp_table = dev_pm_opp_get_opp_table(devfreq->dev.parent);
> +       if (!IS_ERR_OR_NULL(c_opp_table))
> +               c_opp = dev_pm_opp_xlate_opp(opp_table, c_opp_table, opp);
> +       if (c_opp) {
> +               *freq = dev_pm_opp_get_freq(c_opp);
> +               dev_pm_opp_put(c_opp);
> +               goto out;
> +       }
>
>         /*
>          * Get the OPP table's index of decided freqeuncy by governor
> @@ -92,6 +106,13 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>         *freq = child_freq;
>
>  out:
> +       if (!IS_ERR_OR_NULL(opp_table))
> +               dev_pm_opp_put_opp_table(opp_table);
> +       if (!IS_ERR_OR_NULL(c_opp_table))
> +               dev_pm_opp_put_opp_table(c_opp_table);
> +       if (!IS_ERR_OR_NULL(opp))
> +               dev_pm_opp_put(opp);
> +
>         return ret;
>  }
>
> --
> 2.22.0.410.gd8fdbe21b5-goog
>


-- 
Best Regards,
Chanwoo Choi

  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-22  0:34 [PATCH v1 0/3] Add required-opps support to devfreq passive gov Saravana Kannan
2019-06-22  0:34 ` [PATCH v1 1/3] OPP: Allow required-opps even if the device doesn't have power-domains Saravana Kannan
2019-06-22  0:34 ` [PATCH v1 2/3] OPP: Add function to look up required OPP's for a given OPP Saravana Kannan
2019-06-22 11:49   ` Chanwoo Choi
2019-06-22 21:41     ` Saravana Kannan
2019-06-23  4:27       ` Chanwoo Choi
2019-06-23  6:07         ` Saravana Kannan
2019-06-22  0:34 ` [PATCH v1 3/3] PM / devfreq: Add required OPPs support to passive governor Saravana Kannan
2019-06-22 12:00   ` Chanwoo Choi [this message]
2019-06-22 21:45     ` Saravana Kannan
2019-06-24  9:43 ` [PATCH v1 0/3] Add required-opps support to devfreq passive gov Viresh Kumar
2019-06-24 22:17   ` Saravana Kannan
2019-06-25  4:10     ` Viresh Kumar
2019-06-25  5:00       ` Saravana Kannan
2019-06-25  5:22         ` Viresh Kumar
2019-06-25  5:29           ` Saravana Kannan
2019-06-26  6:32             ` Viresh Kumar
2019-06-26 18:10               ` Saravana Kannan
2019-06-28  6:49                 ` Viresh Kumar
2019-06-28 20:26                   ` Saravana Kannan
2019-07-11 23:16                     ` Saravana Kannan

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