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Message-ID: <CAGETcx8QEV+_+d2yt_+bE09mi4qyHZDHPJqPiDXv_HgJPgQJoQ@mail.gmail.com>
Date: Wed, 8 Jan 2020 16:58:32 -0800
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 v6 2/3] OPP: Add support for bandwidth OPP tables
On Wed, Jan 8, 2020 at 2:53 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 06-12-19, 16:24, 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/core.c | 15 +++++++++--
> > drivers/opp/of.c | 63 ++++++++++++++++++++++++++++++++--------------
> > drivers/opp/opp.h | 5 ++++
> > 3 files changed, 62 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index be7a7d332332..c79bbfac7289 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -1282,11 +1282,21 @@ static bool _opp_supported_by_regulators(struct dev_pm_opp *opp,
> > return true;
> > }
> >
> > +int opp_compare_key(struct dev_pm_opp *opp1, struct dev_pm_opp *opp2)
> > +{
> > + if (opp1->rate != opp2->rate)
> > + return opp1->rate < opp2->rate ? -1 : 1;
> > + if (opp1->peak_bw != opp2->peak_bw)
> > + return opp1->peak_bw < opp2->peak_bw ? -1 : 1;
>
> Please also add level here.
I can, but I vaguely remember finding opp-levels could have
duplicates? Am I wrong? If so I can add the opp-level comparison too.
> > + return 0;
> > +}
> > +
> > static int _opp_is_duplicate(struct device *dev, struct dev_pm_opp *new_opp,
> > struct opp_table *opp_table,
> > struct list_head **head)
> > {
> > struct dev_pm_opp *opp;
> > + int opp_cmp;
> >
> > /*
> > * Insert new OPP in order of increasing frequency and discard if
> > @@ -1297,12 +1307,13 @@ static int _opp_is_duplicate(struct device *dev, struct dev_pm_opp *new_opp,
> > * loop.
> > */
> > list_for_each_entry(opp, &opp_table->opp_list, node) {
> > - if (new_opp->rate > opp->rate) {
> > + opp_cmp = opp_compare_key(new_opp, opp);
> > + if (opp_cmp > 0) {
> > *head = &opp->node;
> > continue;
> > }
> >
> > - if (new_opp->rate < opp->rate)
> > + if (opp_cmp < 0)
> > return 0;
> >
> > /* Duplicate OPPs */
> > diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> > index 1cbb58240b80..b565da5a2b1f 100644
> > --- a/drivers/opp/of.c
> > +++ b/drivers/opp/of.c
> > @@ -521,6 +521,44 @@ 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,
> > + bool *rate_not_available)
> > +{
> > + 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;
> > + goto out;
> > + }
> > +
> > + ret = of_property_read_u32(np, "opp-peak-kBps", &bw);
> > + if (!ret) {
> > + new_opp->peak_bw = bw;
> > +
> > + if (!of_property_read_u32(np, "opp-avg-kBps", &bw))
> > + new_opp->avg_bw = bw;
>
> Maybe
> of_property_read_u32(np, "opp-avg-kBps", &new_opp->avg_bw);
>
> and same for opp-peak-kbps as well.
But those are not u32. Is it always safe to directly read into it
across all endian-ness and unsigned int sizes? I get tripped up by
that occasionally.
> > + }
> > +
> > +out:
> > + *rate_not_available = !!ret;
> > + /*
> > + * If ret is 0 at this point, we have already found a key. If we
> > + * haven't found a key yet, then ret already has an error value. In
> > + * either case, we don't need to update ret.
> > + */
> > + of_property_read_u32(np, "opp-level", &new_opp->level);
>
> Yes, it wasn't done earlier but we should do it now. Check level as
> well and treat it as any other key.
>
> I think add a preparatory patch first which does all the cleanup
> before bandwidth thing is added.
Ah come on man! You are making this too painful. It's okay to add a
few more error checks as part of implementing a new feature. Please
don't make me add more patches before this.
> > +
> > + return ret;
> > +}
> > +
> > /**
> > * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
> > * @opp_table: OPP table
> > @@ -558,26 +596,12 @@ 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);
> > - 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__);
> > - goto free_opp;
> > - }
> > -
> > - rate_not_available = true;
> > - } 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;
> > + ret = _read_opp_key(new_opp, np, &rate_not_available);
> > + if (ret) {
> > + dev_err(dev, "%s: opp key field not found\n", __func__);
> > + goto free_opp;
> > }
> >
> > - of_property_read_u32(np, "opp-level", &new_opp->level);
> > -
> > /* Check if the OPP supports hardware's hierarchy of versions or not */
> > if (!_opp_is_supported(dev, opp_table, np)) {
> > dev_dbg(dev, "OPP not supported by hardware: %llu\n", rate);
> > @@ -616,7 +640,8 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
> > if (of_property_read_bool(np, "opp-suspend")) {
> > if (opp_table->suspend_opp) {
> > /* Pick the OPP with higher rate as suspend OPP */
> > - if (new_opp->rate > opp_table->suspend_opp->rate) {
> > + if (opp_compare_key(new_opp,
> > + opp_table->suspend_opp) > 1) {
>
> Maybe leave this place as is as we never want to compare anything else
> but rate.
We do want to support suspend bandwidth. So I think I should have this
fix here so it works in general. Also, why not suspend opp-level?
> > opp_table->suspend_opp->suspend = false;
> > new_opp->suspend = true;
> > opp_table->suspend_opp = new_opp;
> > diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
> > index 01a500e2c40a..0def3154d07b 100644
> > --- a/drivers/opp/opp.h
> > +++ b/drivers/opp/opp.h
> > @@ -57,6 +57,8 @@ extern struct list_head opp_tables;
> > * @suspend: true if suspend OPP
> > * @pstate: Device's power domain's performance state.
> > * @rate: Frequency in hertz
> > + * @peak_bw: Peak bandwidth in kilobytes per second
> > + * @avg_bw: Average bandwidth in kilobytes per second
> > * @level: Performance level
> > * @supplies: Power supplies voltage/current values
> > * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
> > @@ -78,6 +80,8 @@ struct dev_pm_opp {
> > bool suspend;
> > unsigned int pstate;
> > unsigned long rate;
> > + unsigned int peak_bw;
> > + unsigned int avg_bw;
> > unsigned int level;
> >
> > struct dev_pm_opp_supply *supplies;
> > @@ -213,6 +217,7 @@ struct opp_device *_add_opp_dev(const struct device *dev, struct opp_table *opp_
> > void _dev_pm_opp_find_and_remove_table(struct device *dev);
> > struct dev_pm_opp *_opp_allocate(struct opp_table *opp_table);
> > void _opp_free(struct dev_pm_opp *opp);
> > +int opp_compare_key(struct dev_pm_opp *opp1, struct dev_pm_opp *opp2);
>
> make it _opp_compare_key() instead.
Ack.
-Saravana
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