Hi Ulf and Holger, On Thu, Dec 17, 2015 at 2:10 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > The no-1-8-v is a somewhat broken DT binding. I advise people to not > use any more. > Depending on the sdhci variant it have different meanings. > > I guess you are using the sdhci-esdhc-imx variant, which means > no-1-8-v will disable UHS modes for SD-cards (those requiring 1.8V > signal voltage). It has no impact on (e)MMC. > > As the host driver announces support for MMC_CAP_1_8V_DDR, that's what > the mmc core will try to use. Actually the mmc core will first try > 1.8V and if it fails, go for 3.3V. > > Likely, sdhci_do_start_signal_voltage_switch() will success to write > the corresponding registers to change the signal voltage to 1.8V, > which makes the mmc core believe it was a success. > > *If* your statement around that your HW don't support 1.8V signal > voltage, we should perhaps add new mmc cap as currently we don't have > a "MMC_CAP_3_3V_DDR". Although, you need to convince on that, because > my experience tells that quite many has misunderstood the HW design in > this regard. Yes, I have added a 'MMC_CAP_3_3V_ONLY_DDR' in this proposal to fix the same issue as Holger describes: http://www.spinics.net/lists/linux-mmc/msg32285.html ,but it seems you were not happy with such approach at that time. Unfortunately, I was not able to rework it. 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
