Re: MMC runtime PM patches break libertas probe

[Daniel Drake <dsd@laptop.org>]

On 30 May 2011 07:52, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> On Sun, May 29, 2011 at 7:21 PM, Daniel Drake <dsd@laptop.org> wrote:
>> It's certainly possible that there's something weird about the
>> hardware in question, but we *are* able to successfully power down and
>> up the card with a hacky rfkill driver that calls mmc_stop_host /
>> mmc_start_host.
>
> Are we talking about the XO-1.5 and the sd8686 ?

Yes.

> Last we talked, we found out runtime PM didn't work because the sd8686
> required an additional manipulation of an external reset gpio line,
> and that the only reason OLPC could power it down/up was this patch:
>
> http://dev.laptop.org/git/olpc-2.6/commit/?h=olpc-2.6.35&id=e9bee721fb0cc303286d1fe5df4930ce79b0b1e0

My further investigation here suggests that this change is not
necessary. It was added in response to a separate (hard-to-reproduce)
issue and it was never known if it would actually fix that issue, it
was more of a guess. We don't have any convincing evidence that it
helps, so it will be dropped in future.

Anyway, just to be sure, I tried combining this hack with runtime PM,
and also as a regulator, and it didn't help anything. runtime PM still
fails to power up the card.

Sorry for leading you down the wrong path there.

> does mmc_stop_host+mmc_start_host
> work for you without manipulating that reset gpio ?

Yes.

...
> Otherwise, submit :)

Thanks for reviewing, I'll go ahead and clean it up.

You didn't comment on the added mmc_select_voltage() call. Is that one
also sensible?

Thanks,
Daniel