[PATCH] mmc: read alias from device-tree if probing via of.

[Ben Dooks <ben.dooks@codethink.co.uk>]

The mmc host controller fails to check for the presence
of an aliases entry in the device tree when creating a
new mmc host. This means that  mmc bus numbers are not
as specified in the aliases node.

For example, the following on an imx6 would make mmc0
the second sdhci, and mmc2 the first sdhci:

aliases {
	mmc0 = &usdhc2;
	mmc2 = &usdhc0;
}

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Tested-by: Kejia Hu <kejia.hu@codethink.co.uk>
---
 drivers/mmc/core/host.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index abd933b..3bed4d0 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -561,7 +561,11 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 	host->rescan_disable = 1;
 	idr_preload(GFP_KERNEL);
 	spin_lock(&mmc_host_lock);
-	err = idr_alloc(&mmc_host_idr, host, 0, 0, GFP_NOWAIT);
+	err = of_alias_get_id(dev->of_node, "mmc");
+	if (err >= 0)
+		err = idr_alloc(&mmc_host_idr, host, err, err+1, GFP_NOWAIT);
+	if (err < 0)
+		err = idr_alloc(&mmc_host_idr, host, 0, 0, GFP_NOWAIT);
 	if (err >= 0)
 		host->index = err;
 	spin_unlock(&mmc_host_lock);
-- 
2.5.3