diff options
| -rw-r--r-- | drivers/mmc/host/mmci.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index c550b3ebb635..604e41db00db 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -189,6 +189,21 @@ static int mmci_validate_data(struct mmci_host *host, return 0; } +static void mmci_reg_delay(struct mmci_host *host) +{ + /* + * According to the spec, at least three feedback clock cycles + * of max 52 MHz must pass between two writes to the MMCICLOCK reg. + * Three MCLK clock cycles must pass between two MMCIPOWER reg writes. + * Worst delay time during card init is at 100 kHz => 30 us. + * Worst delay time when up and running is at 25 MHz => 120 ns. + */ + if (host->cclk < 25000000) + udelay(30); + else + ndelay(120); +} + /* * This must be called with host->lock held */ @@ -1264,6 +1279,7 @@ static void mmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) mmci_set_clkreg(host, ios->clock); mmci_write_pwrreg(host, pwr); + mmci_reg_delay(host); spin_unlock_irqrestore(&host->lock, flags); |