linux-kernel - Re: [PATCH 3/3] regulator: core: make regulator_register() EPROBE

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Message-ID: <CAKdAkRSneYYjcVe--P=m037aA1DaD+efbEcRGGKVk1hDeEw70A@mail.gmail.com>
Date:   Wed, 18 Sep 2019 08:53:40 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     zhang.chunyan@...aro.org, Doug Anderson <dianders@...omium.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, ckeepax@...nsource.cirrus.com,
        lkml <linux-kernel@...r.kernel.org>,
        Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [PATCH 3/3] regulator: core: make regulator_register()
 EPROBE_DEFER aware

On Wed, Sep 18, 2019 at 1:18 AM Marco Felsch <m.felsch@...gutronix.de> wrote:
>
> On 19-09-17 17:57, Dmitry Torokhov wrote:
> > On Tue, Sep 17, 2019 at 4:42 PM Marco Felsch <m.felsch@...gutronix.de> wrote:
> > >
> > > Sometimes it can happen that the regulator_of_get_init_data() can't
> > > retrieve the config due to a not probed device the regulator depends on.
> > > Fix that by checking the return value of of_parse_cb() and return
> > > EPROBE_DEFER in such cases.
> >
> > Treating EPROBE_DEFER in a special way is usually wrong.
> > regulator_of_get_init_data() may fail for multiple reasons (no memory,
> > invalid DT, etc, etc). All of them should abort instantiating
> > regulator.
>
> Those errors are handled but the behaviour of this funciton is to return
> NULL in such errors which is fine for the caller of this function. I
> only want to handle EPROBE_DEFER special..

And I am saying it is wrong to handle only EPROBE_DEFER.
regulator_of_get_init_data() should always return ERR_PTR()-encoded
error code when parsing callback returns error, so that regulator core
does not mistakenly believe that there is no configuration/init data
when in fact there is, but we failed to handle it properly.

IOW I'm advocating for extending you patch so that it reads:

+               ret = desc->of_parse_cb(child, desc, config);
+               if (ret) {
+                       of_node_put(child);
+                       return ERR_PTR(ret);
+               }

Thanks.

-- 
Dmitry