[alsa-devel] [PATCH 3/7] ASoC: wm8903: generalize GPIO control register bits

[Charles Keepax]

On Thu, Jun 04, 2015 at 10:19:24AM +0100, Mark Brown wrote:
> On Thu, Jun 04, 2015 at 10:30:10AM +0200, Linus Walleij wrote:
> 
> > > +#define WM8903_GPn_PU_MASK                      0x0004  /* GPn_PU */
> > > +#define WM8903_GPn_PU_SHIFT                          2  /* GPn_PU */
> > > +#define WM8903_GPn_PU_WIDTH                          1  /* GPn_PU */
> 
> > Pull-down/pull-up?
> 
> > That is pin control, not GPIO.
> 
> Those register definition defines are just an automatically generated
> dump of the complete CODEC register map, the GPIO pins have some pin
> control type functionality in there.
> 
> > I know I should probably be a bit relaxed on enforcing strict frameworks
> > on ASoC and DRI/DRM alike, because the drivers are complex and sometimes
> > need to be on top of things rather than split things apart and set up
> > complex cobwebs of subsystem cross-dependencies, but I'd
> > like to know a bit more about the design philisophy here.
> 
> > I guess this dates back to the time before the pin control subsystem?
> 
> There's that as well, but more generally I'm not sure if there's even
> any use of those defines for the driver (without looking at the source
> to check).

Many of the drivers contain a gpio defaults style entry in the
pdata, which basically is doing what pin control should be and
setting up the pulls/functions etc. But replacing that in all
the legacy CODECs would be a massive task.

Thanks,
Charles