linux-kernel - Re: [PATCH v2 14/48] opp: Filter out OPPs based on availability of a required-OPP

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Date:   Wed, 23 Dec 2020 09:52:00 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 14/48] opp: Filter out OPPs based on availability of a
 required-OPP

On 22-12-20, 22:17, Dmitry Osipenko wrote:
> 22.12.2020 11:59, Viresh Kumar пишет:
> > On 17-12-20, 21:06, Dmitry Osipenko wrote:
> >> A required OPP may not be available, and thus, all OPPs which are using
> >> this required OPP should be unavailable too.
> >>
> >> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> >> ---
> >>  drivers/opp/core.c | 11 ++++++++++-
> >>  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > Please send a separate patchset for fixes, as these can also go to 5.11 itself.
> 
> Alright, although I don't think that this patch fixes any problems for
> existing OPP users.

Because nobody is using this feature, but otherwise this is a fix for me.

> >> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> >> index d9feb7639598..3d02fe33630b 100644
> >> --- a/drivers/opp/core.c
> >> +++ b/drivers/opp/core.c
> >> @@ -1588,7 +1588,7 @@ int _opp_add(struct device *dev, struct dev_pm_opp *new_opp,
> >>  	     struct opp_table *opp_table, bool rate_not_available)
> >>  {
> >>  	struct list_head *head;
> >> -	int ret;
> >> +	int i, ret;
> >>  
> >>  	mutex_lock(&opp_table->lock);
> >>  	head = &opp_table->opp_list;
> >> @@ -1615,6 +1615,15 @@ int _opp_add(struct device *dev, struct dev_pm_opp *new_opp,
> >>  			 __func__, new_opp->rate);
> >>  	}
> >>  
> >> +	for (i = 0; i < opp_table->required_opp_count && new_opp->available; i++) {
> >> +		if (new_opp->required_opps[i]->available)
> >> +			continue;
> >> +
> >> +		new_opp->available = false;
> >> +		dev_warn(dev, "%s: OPP not supported by required OPP %pOF (%lu)\n",
> >> +			 __func__, new_opp->required_opps[i]->np, new_opp->rate);
> > 
> > Why not just break from here ?
> 
> The new_opp could be already marked as unavailable by a previous voltage
> check, hence this loop should be skipped entirely in that case.

Then add a separate check for that before the loop as we don't need that check
on every iteration here.

-- 
viresh