diff options
| -rw-r--r-- | drivers/mmc/core/mmc.c | 34 |
1 files changed, 25 insertions, 9 deletions
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 31c43165f8bc..69e6273ed228 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -988,19 +988,35 @@ static int mmc_select_hs_ddr(struct mmc_card *card) * 1.8V vccq at 3.3V core voltage (vcc) is not required * in the JEDEC spec for DDR. * - * Do not force change in vccq since we are obviously - * working and no change to vccq is needed. + * Even (e)MMC card can support 3.3v to 1.2v vccq, but not all + * host controller can support this, like some of the SDHCI + * controller which connect to an eMMC device. Some of these + * host controller still needs to use 1.8v vccq for supporting + * DDR mode. + * + * So the sequence will be: + * if (host and device can both support 1.2v IO) + * use 1.2v IO; + * else if (host and device can both support 1.8v IO) + * use 1.8v IO; + * so if host and device can only support 3.3v IO, this is the + * last choice. * * WARNING: eMMC rules are NOT the same as SD DDR */ - if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_DDR_1_2V) { - err = __mmc_set_signal_voltage(host, - MMC_SIGNAL_VOLTAGE_120); - if (err) - return err; - } + err = -EINVAL; + if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_DDR_1_2V) + err = __mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120); - mmc_set_timing(host, MMC_TIMING_MMC_DDR52); + if (err && (card->mmc_avail_type & EXT_CSD_CARD_TYPE_DDR_1_8V)) + err = __mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180); + + /* make sure vccq is 3.3v after switching disaster */ + if (err) + err = __mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330); + + if (!err) + mmc_set_timing(host, MMC_TIMING_MMC_DDR52); return err; } |