[PATCH 4.2 107/134] mmc: sdhci-of-esdhc: add workaround for pre divider initial value

Greg Kroah-Hartman
2015-09-26T21:56:25Z

From: Yangbo Lu <yangbo.lu@freescale.com>

commit 77bd2f6f6c65b4ad259394d416855ed561f21e8f upstream.

For eSDHC(version < 2.3), the pre divider only could divide base clock
by 2 at least. Add workaround for this to avoid unexpected issue.

Signed-off-by: Yangbo Lu <yangbo.lu@freescale.com>
Acked-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Fixes: bd455029d01c ("mmc: sdhci-of-esdhc: Pre divider starts at 1")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/host/sdhci-of-esdhc.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/mmc/host/sdhci-of-esdhc.c
+++ b/drivers/mmc/host/sdhci-of-esdhc.c
@@ -208,6 +208,12 @@ static void esdhc_of_set_clock(struct sd
if (clock == 0)
return;

+ /* Workaround to start pre_div at 2 for VNN < VENDOR_V_23 */
+ temp = esdhc_readw(host, SDHCI_HOST_VERSION);
+ temp = (temp & SDHCI_VENDOR_VER_MASK) >> SDHCI_VENDOR_VER_SHIFT;
+ if (temp < VENDOR_V_23)
+ pre_div = 2;
+
/* Workaround to reduce the clock frequency for p1010 esdhc */
if (of_find_compatible_node(NULL, NULL, "fsl,p1010-esdhc")) {
if (clock > 20000000)