On Mon, 12 Oct 2009 14:11:29 +0100 David Vrabel <david.vrabel@xxxxxxx> wrote: > > In the 3.00 spec, OCR bit 24 is S18R (Signalling 1.8V request). This > is outside of the VDD region (bits 0:23). So I think we can support > non standard DS/HS (Default Speed/High Speed) cards that report 1.8V > operation (in the VDD region) and new UHS-I (Ultra High Speed phase I) > cards without any confusion. > > On a UHS-I capable controller, the software would send ACMD41 with > S18R set and see if the card responses with it set. If so, it tells > the card to switch to 1.8V signalling (CMD11) and tells the > controller to switch to 1.8V signalling and SDR12 mode. The > controller still supplies 3.3V to the card even after the switch. > Later on the host software will query the card to find out what UHS-I > modes are supported and switch card and controller to a faster mode > (if possible). 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. Ohad? --phil -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
