SD2.0 cards need vqmmc and vmmc to be the same. But vqmmc call regulator_set_voltage to set min_uv(2.7v) as far as possible. So if we set vmmc 3.3V in dt table, we will get error information as follows: [ 17.785398] mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0) [ 17.795175] mmc1: new high speed SDHC card at address e624 [ 17.801283] mmcblk1: mmc1:e624 SU08G 7.40 GiB [ 17.816033] mmcblk1: p1 [ 17.839318] mmcblk1: error -110 sending status command, retrying [ 17.845363] mmcblk1: error -115 sending stop command, original cmd response 0x900, card status 0x800b00 [ 17.854758] mmcblk1: error -84 transferring data, sector 32, nr 24, cmd response 0x900, card status 0xb00 [ 17.864328] mmcblk1: retrying using single block read [ 17.873647] mmcblk1: error -110 sending status command, retrying [ 17.879660] mmcblk1: error -84 transferring data, sector 44, nr 12, cmd response 0x900, card status 0x0 [ 17.889051] end_request: I/O error, dev mmcblk1, sector 44 [ 17.895594] Buffer I/O error on device mmcblk1, logical block 5 [ 17.902484] mmcblk1: error -110 sending status command, retrying [ 17.908498] mmcblk1: error -84 transferring data, sector 50, nr 6, cmd response 0x900, card status 0x0 [ 17.917802] end_request: I/O error, dev mmcblk1, sector 50 [ 17.924984] Buffer I/O error on device mmcblk1, logical block 6 [ 18.431258] mmc_host mmc1: Timeout sending command (cmd 0x200000 arg 0x0 status 0x80200000) Signed-off-by: Addy Ke <addy.ke@xxxxxxxxxxxxxx> --- drivers/mmc/host/dw_mmc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index b4c3044..a8b70b5 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1163,8 +1163,14 @@ static int dw_mci_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios) */ uhs = mci_readl(host, UHS_REG); if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) { - min_uv = 2700000; - max_uv = 3600000; + /* try pick the exact same voltage as vmmc for vqmmc */ + if (!IS_ERR(mmc->supply.vmmc)) { + min_uv = regulator_get_voltage(mmc->supply.vmmc); + max_uv = min_uv; + } else { + min_uv = 2700000; + max_uv = 3600000; + } uhs &= ~v18; } else { min_uv = 1700000; -- 1.8.3.2 -- 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