Re: [PATCH 4.16 269/272] pinctrl: msm: Use dynamic GPIO numbering

Greg Kroah-Hartman
2018-05-31T16:04:48Z

On Thu, May 31, 2018 at 10:09:50AM -0500, Timur Tabi wrote:
> On 5/31/18 7:12 AM, Greg Kroah-Hartman wrote:
> > Why is it somehow ok for "future" kernels? You can't break the api in
> > the future for no reason.
> >
> > So this needs to be the same everywhere. If it is broken in 4.17-rc, it
> > needs to be reverted.
>
> This was discussed here:
>
> https://www.spinics.net/lists/linux-arm-msm/msg32572.html
>
> The code can't program the value to 0 *and* support multiple TLMM devices at
> the same time. Prior to 4.18, it is not possible to support multiple TLMMs
> anyway, so blindly setting the base to -1 in the 4.17 kernel just breaks
> existing user-space code that uses the legacy GPIO API.
>
> (This patch in 4.18 is what provides support for multiple TLMMs: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/pinctrl/qcom?id=f265e8b91bb50c7a732a171ddaeb0eef143bacd9)
>
> So you can see in the thread that I proposed a compromise:
>
> https://www.spinics.net/lists/linux-arm-msm/msg32596.html
>
> but that was rejected

Ugh, ok, you all have fun with this :(

I've reverted it from all of the stable trees, again, sorry for it
coming back.

greg k-h