Re: [PATCH] sdio: add MMC_CAP_VDD_165_195 host capability

Pierre Ossman
2009-10-14T08:49:31Z

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On Wed, 14 Oct 2009 09:56:28 +0200
Ohad Ben-Cohen <ohad@wizery.com> wrote:

> On Tue, Oct 13, 2009 at 4:39 AM, Philip Langdale <philipl@overt.org> wrote:
> > Interesting. But that means that Ohad's patch doesn't make much sense;
> > his uses the MMC low voltage OCR bit in an SDIO context. So either, the
> > patch is wrong, or he's dealing with out-of-spec hardware.
>
> Yes, the hardware is out-of-spec. It uses the undefined low voltage
> OCR bit to achieve 1.8V SDIO voltage. By removing the MMC_VDD_165_195
> restriction, commit 27cce39f555def6f5ebe7f03d69ccc44ab25f0b2 makes it
> possible for the hardware to work with unpatched kernels.
>
> Philip, David, Pierre - would you like to remove the MMC_VDD_165_195
> restriction differently ? maybe to revive the MMC_CAP_VDD_165_195 host
> capability patch in some way (see
> http://www.mail-archive.com/linux-mmc@vger.kernel.org/msg00386.html) ?
>

Since this is out-of-spec and therefore possibly dangerous behaviour,
I'd like it to be opt-in for the user. And since it's so early in the
init process, we can't automate it based on card id.

Rgds
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-- Pierre Ossman

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