linux-kernel - Re: [PATCH 5/8] OPP: Allow multiple clocks for a device

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Message-ID: <58cc8e3c-74d4-e432-8502-299312a1f15e@collabora.com>
Date:   Mon, 4 Jul 2022 16:17:30 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Jon Hunter <jonathanh@...dia.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel@...r.kernel.org,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH 5/8] OPP: Allow multiple clocks for a device

On 7/4/22 15:09, Viresh Kumar wrote:
> On 30-06-22, 15:45, Viresh Kumar wrote:
>> On 30-06-22, 12:57, Dmitry Osipenko wrote:
>>> The set_freq_table() gets available freqs using
>>> dev_pm_opp_find_freq_ceil() iteration.
>>>
>>> The first dev_pm_opp_find_freq_ceil(freq=0) succeeds and returns ceil
>>> freq=1.
>>
>> I don't see how this can possibly happen. One possibility is that freq
>> is set to 0 and one the next loop you do freq++, which can make it 1.
>>
>>> The second dev_pm_opp_find_freq_ceil(freq=1) fails with -ERANGE.
>>
>> Even if we send freq = 1, I don't see how we can get ERANGE if the OPP
>> table is properly initialized.
>>
>>> I haven't looked yet at why freq is set to 1.
Actually the freq was 0 and it was 1 on the next loop like you suggested.

>> Thanks, but I would need some help to get it debugged.
> 
> Hi Dmitry,
> 
> I am looking to send another version of this now and soon merge this
> in for 5.20-rc1. Can you please help figure out what's going on here ?

Previously, the _read_opp_key() was always reading the opp-hz. Now it
skips reading the rates in _read_rate() because opp_table->clk_count=0
for the tegra30-devfreq driver the uses devm_pm_opp_of_add_table_noclk().

-- 
Best regards,
Dmitry