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

[Chris Ball <cjb@laptop.org>]

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?

> 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