[PATCH 05/15] omap: hsmmc: add virtual card detect support

[Madhusudhan]

> -----Original Message-----
> From: Ohad Ben-Cohen [mailto:ohad at wizery.com]
> Sent: Tuesday, July 06, 2010 6:48 AM
> To: Nicolas Pitre
> Cc: linux-wireless at vger.kernel.org; linux-mmc at vger.kernel.org; linux-
> omap at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> linux at arm.linux.org.uk; Chikkature Rajashekar Madhusudhan; Luciano Coelho;
> Andrew Morton; San Mehat; Pandita, Vikram
> Subject: Re: [PATCH 05/15] omap: hsmmc: add virtual card detect support
> 
> On Tue, Jul 6, 2010 at 1:22 PM, Ohad Ben-Cohen <ohad at wizery.com> wrote:
> > Note: the wl1271 device does support standard card detection, but
> > AFAIK there's a limitation to use that with the specific omap
> > controller the device is hardwired to. I will try to get more info
> > about that, but probably Madhu can comment on that better.
> 
> 
> Some correction and additional info:
> 
> The wl1271 device has an issue which makes the standard card detect
> mechanism irrelevant: it is always up, even if the power enable gpio
> input of the device is down (the power enable input does not supply
> the power to the chip, it's just logical digital high/low input upon
> which the device reacts).  That's why we must use software control for
> emulating card detect with that device.
> 
> In addition, as far as I could find out, the card detect mechanism on
> the ZOOM is implemented by mechanical means, and thus is not relevant
> for hardwired embedded SDIO devices (I'm not even sure card detect is
> supported for the 3rd mmc controller).

The card detect is supported through T2 GPIO interrupts only for MMC1 and
MMC2. Such a mechanism is not present for MMC3 to which the WLAN chip is
hardwired.

Regards,
Madhu