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authorLinus Torvalds <torvalds@g5.osdl.org>2005-12-14 15:46:46 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-12-14 15:46:46 -0800
commit9d149c27eb1581edd239c0db96a407a4fc5e9f18 (patch)
tree7e1b98ed7c681baff2bb863046d8b1ac9733efa7 /drivers
parent27af4cfd11883073359bd5acab1962b0fa96a3bf (diff)
parent45f8245b972e360c19aec9032e2a2033b8ac3719 (diff)
Merge master.kernel.org:/home/rmk/linux-2.6-mmc
Diffstat (limited to 'drivers')
-rw-r--r--drivers/mmc/mmc.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index b586a83a9b4..eb41391e06e 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -679,7 +679,15 @@ static void mmc_idle_cards(struct mmc_host *host)
}
/*
- * Apply power to the MMC stack.
+ * Apply power to the MMC stack. This is a two-stage process.
+ * First, we enable power to the card without the clock running.
+ * We then wait a bit for the power to stabilise. Finally,
+ * enable the bus drivers and clock to the card.
+ *
+ * We must _NOT_ enable the clock prior to power stablising.
+ *
+ * If a host does all the power sequencing itself, ignore the
+ * initial MMC_POWER_UP stage.
*/
static void mmc_power_up(struct mmc_host *host)
{