linux-kernel - Re: [PATCH] opp: Don't ignore clk

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Message-ID: <a7585f81-ed88-06d7-c1c5-4b3052fc0aaa@gmail.com>
Date:   Fri, 29 Jan 2021 22:26:17 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] opp: Don't ignore clk_get() errors other than -ENODEV

29.01.2021 20:46, Viresh Kumar пишет:
> On 29-01-21, 18:23, Dmitry Osipenko wrote:
>> 29.01.2021 13:51, Viresh Kumar пишет:
>>> Not all devices that need to use OPP core need to have clocks, a missing
>>> clock is fine in which case -ENODEV shall be returned by clk_get().
>>>
>>> Anything else is an error and must be handled properly.
>>>
>>> Reported-by: Dmitry Osipenko <digetx@...il.com>
>>> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
>>> ---
>>> Stephen, is the understanding correct that -ENODEV is the only error
>>> returned for missing clocks ?
>>>
>>> Dmitry: I hope this is on the lines of what you were looking for ?
>>
>> Viresh, thank you! This is not what I was looking for because clk core
>> doesn't return -ENODEV for a missing clock, but -ENOENT. The ENODEV
>> certainly should break drivers.
> 
> My bad.
>  
>> I was looking for this:
>>
>> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
>> index 0305861fee1b..3dd9cdbc0e75 100644
>> --- a/drivers/opp/core.c
>> +++ b/drivers/opp/core.c
>> @@ -1264,7 +1264,7 @@ static struct opp_table
>> *_update_opp_table_clk(struct device *dev,
>>  	if (IS_ERR(opp_table->clk)) {
>>  		int ret = PTR_ERR(opp_table->clk);
>>
>> -		if (ret == -EPROBE_DEFER) {
>> +		if (ret != -ENOENT) {
>>  			dev_pm_opp_put_opp_table(opp_table);
>>  			return ERR_PTR(ret);
>>  		}
> 
> You should be looking for this instead, isn't it ?
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 049d45e70807..4bfcbe5b57af 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1268,7 +1268,7 @@ static struct opp_table *_update_opp_table_clk(struct device *dev,
>         if (!ret)
>                 return opp_table;
>  
> -       if (ret == -ENODEV) {
> +       if (ret == -ENOENT) {
>                 dev_dbg(dev, "%s: Couldn't find clock: %d\n", __func__, ret);
>                 return opp_table;
>         }
> 
> 

This will work too.

Then also could be better to replace the "if (ret != -EPROBE_DEFER)"
with dev_err_probe(..).