2012/12/8 Chris Ball <[email protected]>: > Hi, > > On Mon, Nov 19 2012, Kevin Liu wrote: >> In fact, I don't think 3.3v vccq for emmc can work under DDR50 mode >> with SD host. > > I've checked on the scope that we're reaching DDR50 with our 3.3V vccq > eMMC, so it looks like this isn't true. >
Chris, Thanks for the check. If you are using sdhci-pxav3.c, 3.3v vccq can work since it enabled the 1.8v signaling in the callback function set_uhs_signaling. What I want to say is if you don't enable the 1.8v signaling bit while using 3.3v vccq, DDR50 on emmc should NOT work. (Use default sdhci code without implementing set_uhs_signaling as the other drivers.) You can just remove the set_uhs_signaling in sdhci-pxav3.c and try again. So we should do this in sdhci.c by default and remove the callback function, which only aim to enabling the 1.8v signaling bit. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
