[alsa-devel] [PATCH 01/14] Documentation: Add SoundWire summary

Mark Brown broonie at kernel.org
Mon Oct 23 09:50:50 CEST 2017


On Sat, Oct 21, 2017 at 04:58:40PM +0530, Vinod Koul wrote:
> On Sat, Oct 21, 2017 at 09:57:44AM +0100, Mark Brown wrote:

> > There's lots of perfectly normal nouns in this document like Slave here
> > which are randomly capitalized.  Is there some great reason for this?
> > It makes the document pretty distracting to read.

> Slave, SoundWire etc are MIPI definitions hence capitalized.

Slave?  Really?

> > > +provides capabilities information. DT support is not implemented at this
> > > +time but should be trivial to add since capabilities are enabled with the
> > > +device_property_ API.

> > Since we're making this up from whole cloth rather than following an
> > existing standard let's get a DT binding document together and review
> > the properties that are getting defined.

> I don't have a DT to test, but looking at Slimbus code I guess assumptions
> are fair and we seem to have similar concepts and implementation.

That's fine, we can still review binding documents.

> > > +The MIPI specification requires each Slave interface to expose a unique
> > > +48-bit identifier, stored in 6 read only dev_id registers. This dev_id
> > > +identifier contains vendor and part information, as well as a field enabling
> > > +to differentiate between identical components. An additional class field is
> > > +currently unused. Slave driver is written for the specific 48-bit
> > > +identifier, Bus enumerates the Slave device based on the 48-bit identifier.

> > So this says that the instance identifer is part of the device
> > identifier but the driver should bind to the whole device identifer?
> > I'd expect the driver to bind to everything except the instance
> > identifer.

> Other parts are still TBD and not really used, like Device Class, Spec
> version. We are using only mfg id and part id for binding.

That's not what the document claims.
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