Re: [alsa-devel] [PATCH v3 2/2] ASoC: imx-wm8962: Fix codec_clk cleanup

[Daniel Baluta <daniel.baluta@gmail.com>]

On Tue, Mar 28, 2017 at 6:24 PM, Mark Brown <broonie@kernel.org> wrote:
> On Tue, Mar 28, 2017 at 12:53:06PM +0100, Charles Keepax wrote:
>> On Tue, Mar 28, 2017 at 01:47:04PM +0300, Daniel Baluta wrote:
>
>> > >> -     codec_clk = devm_clk_get(&codec_dev->dev, NULL);
>> > >> +     codec_clk = clk_get(&codec_dev->dev, NULL);
>
>> > is different from &codec_dev->dev.
>
>> I get that they are different, I just don't get why changing
>> from a devm_clk_get to a clk_get is a better fix than changing
>> &codec->dev to &pdev->dev.
>
> This should be clear from the semantics of clk_get(): you're looking up
> the clock in the context of the supplied device and the clock is
> attached to the CODEC so you need to look up in the CODEC context.  What
> would be even better would be to move the allocation of the clock into
> the CODEC driver...

If I read the code correctly, both machine and codec driver are doing:

* codec_clk = clk_get(...)

I guess that the codec driver is the first to be loaded and it will call:

* __clk_create_clk

which will do the allocation. Then when machine driver is loaded, it
will only take a reference to the allocated clock.

I might be very wrong on this. Can you clarify what does moving allocation
of the clock into codec driver implies? Machine driver only needs a reference
to codec_clk to just get the clock's rate.

Daniel.