mmc: increase power up delay
Increase delay for power up in order to support some slower boards.
Also add some comments about why the delays are there.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 3bebd3b..bffcaf8 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -460,12 +460,20 @@
host->ios.timing = MMC_TIMING_LEGACY;
mmc_set_ios(host);
- mmc_delay(1);
+ /*
+ * This delay should be sufficient to allow the power supply
+ * to reach the minimum voltage.
+ */
+ mmc_delay(2);
host->ios.clock = host->f_min;
host->ios.power_mode = MMC_POWER_ON;
mmc_set_ios(host);
+ /*
+ * This delay must be at least 74 clock sizes, or 1 ms, or the
+ * time required to reach a stable voltage.
+ */
mmc_delay(2);
}