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Date: Tue, 20 Aug 2019 15:27:24 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: 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>,
Georgi Djakov <georgi.djakov@...aro.org>,
Vincent Guittot <vincent.guittot@...aro.org>,
"Sweeney, Sean" <seansw@....qualcomm.com>,
David Dai <daidavid1@...eaurora.org>, adharmap@...eaurora.org,
Rajendra Nayak <rnayak@...eaurora.org>,
Sibi Sankar <sibis@...eaurora.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Evan Green <evgreen@...omium.org>,
Android Kernel Team <kernel-team@...roid.com>,
Linux PM <linux-pm@...r.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/3] OPP: Add support for bandwidth OPP tables
On Mon, Aug 19, 2019 at 11:13 PM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 07-08-19, 15:31, Saravana Kannan wrote:
> > Not all devices quantify their performance points in terms of frequency.
> > Devices like interconnects quantify their performance points in terms of
> > bandwidth. We need a way to represent these bandwidth levels in OPP. So,
> > add support for parsing bandwidth OPPs from DT.
> >
> > Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> > ---
> > drivers/opp/of.c | 41 ++++++++++++++++++++++++++++++++---------
> > drivers/opp/opp.h | 4 +++-
> > 2 files changed, 35 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> > index 1813f5ad5fa2..e1750033fef9 100644
> > --- a/drivers/opp/of.c
> > +++ b/drivers/opp/of.c
> > @@ -523,6 +523,35 @@ void dev_pm_opp_of_remove_table(struct device *dev)
> > }
> > EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);
> >
> > +static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np)
> > +{
> > + int ret;
> > + u64 rate;
> > + u32 bw;
> > +
> > + ret = of_property_read_u64(np, "opp-hz", &rate);
> > + if (!ret) {
> > + /*
> > + * Rate is defined as an unsigned long in clk API, and so
> > + * casting explicitly to its type. Must be fixed once rate is 64
> > + * bit guaranteed in clk API.
> > + */
> > + new_opp->rate = (unsigned long)rate;
> > + return 0;
> > + }
> > +
>
> Please read opp-level also here and do error handling.
Can you please explain what's the reasoning? opp-level doesn't seem to
be a "key" based on looking at the code.
>
> > + ret = of_property_read_u32(np, "opp-peak-kBps", &bw);
> > + if (ret)
> > + return ret;
> > + new_opp->rate = (unsigned long) bw;
> > +
> > + ret = of_property_read_u32(np, "opp-avg-kBps", &bw);
> > + if (!ret)
> > + new_opp->avg_bw = (unsigned long) bw;
>
> If none of opp-hz/level/peak-kBps are available, print error message here
> itself..
But you don't print any error for opp-level today. Seems like it's optional?
>
> > +
> > + return 0;
>
> You are returning 0 on failure as well here.
Thanks.
> > +}
> > +
> > /**
> > * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
> > * @opp_table: OPP table
> > @@ -560,22 +589,16 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
> > if (!new_opp)
> > return ERR_PTR(-ENOMEM);
> >
> > - ret = of_property_read_u64(np, "opp-hz", &rate);
> > + ret = _read_opp_key(new_opp, np);
> > if (ret < 0) {
> > /* "opp-hz" is optional for devices like power domains. */
> > if (!opp_table->is_genpd) {
> > - dev_err(dev, "%s: opp-hz not found\n", __func__);
> > + dev_err(dev, "%s: opp-hz or opp-peak-kBps not found\n",
> > + __func__);
> > goto free_opp;
> > }
> >
> > rate_not_available = true;
>
> Move all above as well to read_opp_key().
Ok. I didn't want to print an error at the API level and instead print
at the caller level. But if that's what you want, that's fine by me.
>
> > - } else {
> > - /*
> > - * Rate is defined as an unsigned long in clk API, and so
> > - * casting explicitly to its type. Must be fixed once rate is 64
> > - * bit guaranteed in clk API.
> > - */
> > - new_opp->rate = (unsigned long)rate;
> > }
> >
> > of_property_read_u32(np, "opp-level", &new_opp->level);
> > diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
> > index 01a500e2c40a..6bb238af9cac 100644
> > --- a/drivers/opp/opp.h
> > +++ b/drivers/opp/opp.h
> > @@ -56,7 +56,8 @@ extern struct list_head opp_tables;
> > * @turbo: true if turbo (boost) OPP
> > * @suspend: true if suspend OPP
> > * @pstate: Device's power domain's performance state.
> > - * @rate: Frequency in hertz
> > + * @rate: Frequency in hertz OR Peak bandwidth in kilobytes per second
> > + * @avg_bw: Average bandwidth in kilobytes per second
>
> Please add separate entry for peak_bw here.
>
> I know you reused rate because you don't want to reimplement the helpers we
> have. Maybe we can just update them to return peak_bw when opp-hz isn't present.
How about I just rename this to "key"? That makes a lot more sense
than trying to save 3 different keys and going through them one at a
time.
> > * @level: Performance level
> > * @supplies: Power supplies voltage/current values
> > * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
> > @@ -78,6 +79,7 @@ struct dev_pm_opp {
> > bool suspend;
> > unsigned int pstate;
> > unsigned long rate;
> > + unsigned long avg_bw;
> > unsigned int level;
> >
> > struct dev_pm_opp_supply *supplies;
> > --
> > 2.23.0.rc1.153.gdeed80330f-goog
-Saravana
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