Re: [PATCH] sdhci: Forward EPROBE_DEFER on vmmc and vqmmc regulators

[Mike Looijmans]

ïOn 04/07/2014 02:51 PM, Arnd Bergmann wrote:
> On Monday 07 April 2014 14:32:20 Mike Looijmans wrote:
> > On 04/07/2014 02:25 PM, Arnd Bergmann wrote:
> >
> > Judging from the kernel output, regulator_get_optional returns -ENODEV if the
> > supply wasn't found.
> >
> > Maybe the API is confusing (or wrong?) here.
> >
> > If you change the code as per your suggestion, the SD will not work unless you
> > explicitly assign supplies. And judging from what I've seen so far, I am the
> > first to have ever attached a power supply to this controller...
>
> It's certainly not very "optional" if it returns an error here.
>
> You could try to special-case the "-ENODEV" return here, but I think it
> would be better to change the regulator interface to be less confusing.

Judging from the code:
http://lxr.free-electrons.com/source/drivers/regulator/core.c#L1476

The behaviour is supposed to be something like "regulator_get_optional" will 
return an error if the supply wasn't found, but "regulator_get" will create a 
dummy supply for you instead of returning an error code.

So "regulator_get_optional" means: "I handle my own problems, just gimme the 
bad news". But "regulator_get" appears to imply: "I will shoot the messenger, 
so do whatever you can to get me something to say 'enable' to".

In this case, the IS_NULL part is wrong indeed, it will never return NULL.

I still think it's unrelated to my patch and should be submitted separately.

Mike.


Met vriendelijke groet / kind regards,

Mike Looijmans

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