linux-kernel - Re: [PATCH 1/4] OPP: Add dev_pm_opp_xlate_performance

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Date:   Fri, 23 Nov 2018 14:41:18 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>
Cc:     ulf.hansson@...aro.org, Viresh Kumar <vireshk@...nel.org>,
        Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        niklas.cassel@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] OPP: Add dev_pm_opp_xlate_performance_state() helper

On 22-11-18, 11:38, Viresh Kumar wrote:
> So there are few complexities in the case where an OPP table points to itself in
> the required-opp field. I looked at solving it up in the opp core but that gets
> more and more messy.
> 
> Now there is actually a assumption within the OPP core. Your Mx domain should
> get initialized before the Cx domain, as that is when the OPP tables are created
> as well. This is because Cx's OPP table will point to Mx's OPP table (doesn't
> matter if they share the same table or not) and so Mx's OPP table should come
> first.
> 
> Can you check if that is already the case for you? If not, please try doing it
> and lemme know if it works. It should.
> 
> I just want to avoid too much complexity in OPP core without much use.

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 7f338d39809a..09df3fbdb555 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1734,7 +1734,7 @@ unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
        int i;
 
        for (i = 0; i < src_table->required_opp_count; i++) {
-               if (src_table->required_opp_tables[i] == dst_table)
+               if (src_table->required_opp_tables[i]->np == dst_table->np)
                        break;
        }

Try this fix and it should make it work for you.

Having said that, the way you are representing all your domains with a
single OPP table look incorrect. You are using the same OPP table for
around 10 power domains, all provided by a single provider. This is
absolutely fine. But the Mx domain doesn't have any dependency on any
other domain actually and so its OPPs should never have the
"required-opps" property, but it has those properties in your setup as
you are trying to use the same OPP table. That may all work fine with
the above patch (which is required anyway as it fixes a valid issue),
but you may see a error warning that something failed for Mx domain,
as it has required-opps property but no required device or genpd.

Anyway, please test above first and then you can fix your tables :)

-- 
viresh