mmc: sdhci-of-esdhc: add workaround for pre divider initial value

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>

diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
index 797be7549a15c01a0e9acda2b0adaccb0a6c9416..653f335bef1516ca9aba102e1f3ab21d99a754ce 100644 (file)
--- 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 sdhci_host *host, unsigned int clock)
        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)