mmc: sdhci-s3c: Fix mmc card I/O problem

BugLink: http://bugs.launchpad.net/bugs/868628

commit 49bb1e619568ec84785ceb366f07db2a6f0b64cc upstream.

This patch fixes the problem in sdhci-s3c host driver for Samsung Soc's.
During the card identification stage the mmc core driver enumerates for
the best bus width in combination with the highest available data rate.
It starts enumerating from the highest bus width (8) to lowest width (1).

In case of few MMC cards the 4-bit bus enumeration fails and tries
the 1-bit bus enumeration. When switched to 1-bit bus mode the host driver
has to clear the previous bus width setting and apply the new setting.

The current patch will clear the previous bus mode and apply the new
mode setting.

Signed-off-by: Girish K S <girish.shivananjappa@linaro.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/mmc/host/sdhci-s3c.c b/drivers/mmc/host/sdhci-s3c.c
index 69e3ee321eb..8cd999f4af5 100644
--- a/drivers/mmc/host/sdhci-s3c.c
+++ b/drivers/mmc/host/sdhci-s3c.c
@@ -301,6 +301,8 @@ static int sdhci_s3c_platform_8bit_width(struct sdhci_host *host, int width)
                 ctrl &= ~SDHCI_CTRL_8BITBUS;
                 break;
         default:
+                ctrl &= ~SDHCI_CTRL_4BITBUS;
+                ctrl &= ~SDHCI_CTRL_8BITBUS;
                 break;
         }