Re: Sparse GPIO maps with pinctrl-msm.c?

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Fri 16 Jun 08:49 PDT 2017, Timur Tabi wrote:

> On 6/16/17 10:41 AM, Stephen Boyd wrote:
> > On 06/16, Timur Tabi wrote:
> > > On 6/16/17 10:07 AM, Stephen Boyd wrote:
> > > > I'm not aware of anything in pinctrl-msm to support this.
> > > 
> > > It seems to me like the 'npins' field in msm_pingroup should be
> > > deleted, because it can only ever be 1.
> > 
> > Ok. But does that change anything about this problem?
> 
> No, but at least no one would ever be fooled into thinking that you can have
> sparse GPIO maps when using pinctrl-msm.
> 

As GPIOs are both identified by name and by index within the controller
I don't see it as sufficient to play games with just lowering
npins/ngpios and compacting the lists.

[..]
> > We've already run into this problem on mobile platforms where
> > certain pins are locked down and the approach has been to not
> > care. But I don't think we have your patch yet, so you're the
> > first one to run into this problem.
> 
> For now, I've decided that I'm just going to expose the qdss_tracedata[]
> pins as GPIOs, numbered 0 .. n-1.  However, there's no consensus on that,
> either.
> 

Exposing a subset of GPIOs with a different numbering than what's in the
hardware documentation is going to be quite confusing for the users.


Just to confirm, are the qdss_tracedata the only GPIOs that you want to
expose from the TLMM now? Are those consecutive?

> Being able to designate specific pins as absent would make everyone happy.
> 

I agree.

Regards,
Bjorn