On Mon, Jun 15, 2015 at 9:23 AM, Fabio Estevam <festevam@xxxxxxxxx> wrote: > Hi Ulf, > > On Mon, Jun 15, 2015 at 9:08 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > >> What card (eMMC, SD, MMC) and which host driver is being used here? > > It is an eMMC and the host driver is sdhci-esdhc-imx.c. > >>> --- a/drivers/mmc/core/host.c >>> +++ b/drivers/mmc/core/host.c >>> @@ -527,6 +527,8 @@ int mmc_of_parse(struct mmc_host *host) >>> host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR; >>> if (of_find_property(np, "mmc-hs400-1_2v", &len)) >>> host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR; >>> + if (of_find_property(np, "no-1-8-v", &len)) >>> + host->caps2 |= MMC_CAP_3_3V_ONLY_DDR; >> >> Do you intend to use 3.3V as the I/O voltage level for an eMMCs >> running in DDR mode? Isn't that violation of the eMMC spec? > > Yes, I would like to use 3.3V as the I/O voltage level for an eMMC in DDR mode. > > This was the behaviour prior to 312449efd16bb0, which I would like to > keep so that our custom board based on mx6sl could work. It works fine > with 3.14 kernel, but not on 4.1-rc due to the fact that the board > cannot provide 1.8V level, hence 'no-1-8-v' property is passed in the > device tree. With this patch applied 3.3V is applied and the eMMC can > successfully operate in 3.3V DDR mode. Also, looked at the eMMC spec and the only restriction I saw about using 3.3V voltage is with HS200 or HS400 devices: "VCCQ (I/O) 3.3 V range is not supported in either HS200 or HS400 devices" Regards, Fabio Estevam -- 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
