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@xxxxxxxxxxxxx>
---
drivers/mmc/host/sdhci-of-esdhc.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
index 797be75..653f335 100644
--- 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)
--
2.1.0.27.g96db324
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