linux-kernel - Re: [PATCH v9 5/8] soc/tegra: pmc: Implement get_performance

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Date:   Fri, 27 Aug 2021 07:15:38 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>, Nishanth Menon <nm@...com>,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v9 5/8] soc/tegra: pmc: Implement get_performance_state()
 callback

27.08.2021 07:13, Viresh Kumar пишет:
> On 27-08-21, 07:08, Dmitry Osipenko wrote:
>> 27.08.2021 07:02, Viresh Kumar пишет:
>>> On 27-08-21, 06:47, Dmitry Osipenko wrote:
>>>> Actually, it doesn't work.
>>>>
>>>> The devm_tegra_core_dev_init_opp_table() needs to set clk to support older device-tree and now OPP table already has clk being set.
>>>>
>>>> WARNING: CPU: 2 PID: 92 at drivers/opp/core.c:2146 dev_pm_opp_set_clkname+0x97/0xb8
>>>> Modules linked in:
>>>> CPU: 2 PID: 92 Comm: kworker/u8:1 Tainted: G        W         5.14.0-rc7-next-20210826-00181-g6389463cbb0a #9318
>>>> Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
>>>> Workqueue: events_unbound deferred_probe_work_func
>>>> [<c010cc91>] (unwind_backtrace) from [<c0108d35>] (show_stack+0x11/0x14)
>>>> [<c0108d35>] (show_stack) from [<c0a6c1bd>] (dump_stack_lvl+0x2b/0x34)
>>>> [<c0a6c1bd>] (dump_stack_lvl) from [<c011fc47>] (__warn+0xbb/0x100)
>>>> [<c011fc47>] (__warn) from [<c0a696e3>] (warn_slowpath_fmt+0x4b/0x80)
>>>> [<c0a696e3>] (warn_slowpath_fmt) from [<c07407b3>] (dev_pm_opp_set_clkname+0x97/0xb8)
>>>> [<c07407b3>] (dev_pm_opp_set_clkname) from [<c07407e3>] (devm_pm_opp_set_clkname+0xf/0x64)
>>>> [<c07407e3>] (devm_pm_opp_set_clkname) from [<c050735b>] (devm_tegra_core_dev_init_opp_table+0x23/0x144)
>>>
>>> Why are you calling this anymore ?
>>
>> Older device-trees don't have OPPs, meanwhile drivers will use
>> dev_pm_opp_set_rate() and it requires OPP table to be set up using
>> devm_pm_opp_set_clkname().
>>
>> The devm_tegra_core_dev_init_opp_table() is a common helper that sets up
>> OPP table for Tegra drivers and it sets the clk.
> 
> Ahh, I see. that's okay then. Just add a comment over it to specify the same.
> Doing devm_pm_opp_set_clkname(dev, NULL) is special and looks suspicious
> otherwise.

I'll add comment, thanks.