linux-kernel - Re: [PATCH 2/2] opp: Manage empty OPP tables with clk handle

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Message-ID: <c8e42b38-8ce0-c02c-98d3-6d6598dc3fad@codeaurora.org>
Date:   Wed, 3 Jul 2019 16:17:15 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     vireshk@...nel.org, sboyd@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/2] opp: Manage empty OPP tables with clk handle



On 7/3/2019 3:17 PM, Viresh Kumar wrote:
> On 03-07-19, 14:41, Rajendra Nayak wrote:
>> []..
>>>
>>> Explain the rationale behind this code here in a comment.
>>>
>>>> +	if (!_get_opp_count(opp_table)) {
>>>> +		ret = _generic_set_opp_clk_only(dev, clk, freq);
>>>> +		goto put_opp_table;
>>>> +	}
>>>> +
>>>>    	temp_freq = old_freq;
>>>>    	old_opp = _find_freq_ceil(opp_table, &temp_freq);
>>>>    	if (IS_ERR(old_opp)) {
>>>
>>> Also, rebase over the OPP branch please:
>>
>> thanks, I will fix/rebase and repost,
>> in the meantime while I was testing this a little more I realized I also need
>> something like the change below to avoid a refcount mismatch WARN when empty OPP
>> table is removed using dev_pm_opp_of_remove_table()
>>
>> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
>> index fa7d4d6d37b3..20128a88baf2 100644
>> --- a/drivers/opp/core.c
>> +++ b/drivers/opp/core.c
>> @@ -2118,7 +2118,8 @@ void _dev_pm_opp_find_and_remove_table(struct device *dev)
>>                  return;
>>          }
>> -       _put_opp_list_kref(opp_table);
>> +       if (_get_opp_count(opp_table))
>> +               _put_opp_list_kref(opp_table);
>>          /* Drop reference taken by _find_opp_table() */
>>          dev_pm_opp_put_opp_table(opp_table);
>>
>> Does this look like a good way to fix it?
> 
> No. If an OPP table only has dynamic OPPs, this will still generate
> warning. Below is the fix I would suggest. Please test it, I haven't
> tested it at all :)

thanks, yes, this seems to work.

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