On 11/21/2014 09:06 PM, Ulf Hansson wrote: > [...] > >> Sure >> If the first card is sd2.0 since startup, dw_mci_switch_voltage will not be called, > > That can't be right. mmc_power_up() should trigger > dw_mci_switch_voltage() to be invoked. Since dw_mci_switch_voltage() is invoked, voltage is changed from 1.8v to 2.7v (minimum value 2.7-3.6v), isn't? > >> and card can be identified. But if UHS card is pulgged in first, the vqmmc will be down to 1.8v. >> >> when sd2.0 card is pulgged in, mmc core will call dw_mci_switch_voltage to change vqmmc to 3.3v >> (MMC_SINGLE_VOTAGE_330). So vqmmc will be set 2.7v, if we request 2.7-3.6v. >> >> But vmmc is always 3.3v,becuase it be set min_volt = max_volt = 3.3v in dt tables. vmmc is fixed voltage? >> >> So the result: >> vmmc = 3.3v and vqmmc = 2.7v, and sd2.0 card is failed to identify in my test. > > Hmm. I wonder why it works the first time? Could it be that your > regulator have voltage ramp up time that isn't properly considered? if oscilloscope can use, can we know more exactly? Best Regards, Jaehoon Chung > > Kind regards > Uffe > -- > 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 > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
