Re: [PATCH 3/3] MMC: sdhci-dove: allow GPIOs to be used for card detection on Dove

Guennadi Liakhovetski
2012-12-04T16:01:14Z

Hi Chris

On Mon, 3 Dec 2012, Chris Ball wrote:

> Hi Guennadi,
>
> On Mon, Nov 26 2012, Guennadi Liakhovetski wrote:
> >> Guennadi, what are your thoughts about consolidating this reset logic
> >> between the sdhci tasklet and slot-gpio? It would certainly be nice to
> >> use slot-gpio in cases like this one, so it's worth fixing.
> >
> > Sure, this can be added. As for how - I see at least two possibilities:
> > (1) put the complete above block in a new mmc host operation and just call
> > it from the GPIO card-detect ISR, (2) taking into account, that many
> > (nearly all? all?) host drivers keep a pointer to the current mrq in their
> > private data struct, we could instead add such a pointer to struct
> > mmc_host, then the check "request in progress" could also be generalised,
> > and the operation would just have to reset the host and complete the
> > request (in the sdhci case schedule the task).
>
> They both sound pretty attractive. Maybe we start out with (1), which
> would create a patch we could more reasonably send to stable@ to get
> slot-gpio handling the reset during transfers properly in older kernels,
> and then refactor into (2) later?

Just posted 3 patches for this, have a look if that's what you were
thinking about. Not sure though why this is needed for stable, but I'm
probably just missing some crucial information on the topic.

Thanks
Guennadi

> > Note, that there's already a .hw_reset() operation, used by sdhci-pci
> > only so far, still, it seems we cannot (easily) hijack it.
>
> That one's implementing an eMMC 4.5 spec feature, not related to this
> kind of reset.
>
> Thanks!
>
> - Chris.
> --
> Chris Ball <cjb@laptop.org> <http://printf.net/>
> One Laptop Per Child
>

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer