[alsa-devel] [PATCH V4 1/4] ASoC: Samsung: I2S: Add quirks as driver data in I2S

Mark Brown broonie at kernel.org
Tue Aug 13 01:13:27 CEST 2013

On Mon, Aug 12, 2013 at 04:57:53PM -0600, Stephen Warren wrote:
> On 08/12/2013 03:49 AM, Padmavathi Venna wrote:

> > +- compatible : should be one of the following.
> > +   - samsung,s3c6410-i2s: for 8/16/24bit stereo I2S.
> > +   - samsung,s5pv210-i2s: for 8/16/24bit multichannel(5.1) I2S with
> > +     secondary fifo, s/w reset control and internal mux for root clk src.

> Those descriptions seem a little odd. If I have an SoC that isn't
> s5pv210, yet supports "8/16/24bit multichannel(5.1) I2S with secondary
> fifo, s/w reset control and internal mux for root clk src", will
> compatible="samsung,s5pv210-i2s" work for my HW?

> I wonder if you should instead include the IP block version in the
> compatible value?

We've been round this loop several times, I'd prefer the IP block
versions too but they're at best patchily documented and so as a general
policy the Samsung bindings use the name of the SoC an IP first appeared
in as the version.

> In other words, I don't think we have an answer to the question: Should
> differences between similar HW blocks be encoded into DT properties, or
> should the driver encode them into some table, and look them up from
> compatible value?

For usability it seems better to just be able to say which IP you've
got, this also makes it easier to implement support for new IP features
later on without having to go back and add new properties which would be

> (although I dare say that at least samsung,supports-rstclr should be
> modified to use the new reset controller bindings)

Really?  That doesn't seem terribly sane - I had thought that was for
bodging resets on the side of things that don't normally have them or
need board specific logic.  Also note that this is actually a magic
register write done to reset the IP on some specific IPs.
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