[PATCH] mmc: dw_mmc: Turn the card clock off at suspend time

Doug Anderson dianders at chromium.org
Wed Nov 19 10:51:13 PST 2014

Since the dw_mmc driver was first added to Linux it's had a TODO in it
that we should turn off the card clock during suspend.  I have no idea
for sure why it wasn't done originally, but if I had to guess I'd
guess it was related to the lack of a common clock framework.  Let's
do it now.

There is no reason for the card clock to be left on during suspend and
most systems will eventually turn it off anyway (when whole clock
trees are disabled).  However, it's good to be explicit that it's
disabled at the time that the MMC subsystem is disabled.

This actually fixes a bug on Rockchip rk3288 where an SDIO card wakes
the system back up during suspend.

Signed-off-by: Doug Anderson <dianders at chromium.org>
 drivers/mmc/host/dw_mmc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 5a37c33..c448159 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2825,11 +2825,10 @@ EXPORT_SYMBOL(dw_mci_remove);
- * TODO: we should probably disable the clock to the card in the suspend path.
- */
 int dw_mci_suspend(struct dw_mci *host)
+	clk_disable(host->ciu_clk);
 	return 0;
@@ -2838,6 +2837,8 @@ int dw_mci_resume(struct dw_mci *host)
 	int i, ret;
+	clk_enable(host->ciu_clk);
 	if (!dw_mci_ctrl_reset(host, SDMMC_CTRL_ALL_RESET_FLAGS)) {
 		ret = -ENODEV;
 		return ret;

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