[PATCH 2/4] sdhci-of: Avoid writing reserved bits into host control register

Anton Vorontsov avorontsov at ru.mvista.com
Sat Aug 8 02:49:57 EST 2009


SDHCI core tries to write HISPD bit into the host control register,
but the eSDHC controllers don't have that bit, and that causes
all sorts of misbehaviour when using 4-bit mode capable SD cards.

Signed-off-by: Anton Vorontsov <avorontsov at ru.mvista.com>
---
 drivers/mmc/host/sdhci-of.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of.c b/drivers/mmc/host/sdhci-of.c
index 92b5667..8440fd9 100644
--- a/drivers/mmc/host/sdhci-of.c
+++ b/drivers/mmc/host/sdhci-of.c
@@ -48,6 +48,8 @@ struct sdhci_of_host {
 #define ESDHC_CLOCK_HCKEN	0x00000002
 #define ESDHC_CLOCK_IPGEN	0x00000001
 
+#define ESDHC_HOST_CONTROL_RES	0x05
+
 static u32 esdhc_readl(struct sdhci_host *host, int reg)
 {
 	return in_be32(host->ioaddr + reg);
@@ -109,6 +111,10 @@ static void esdhc_writeb(struct sdhci_host *host, u8 val, int reg)
 	int base = reg & ~0x3;
 	int shift = (reg & 0x3) * 8;
 
+	/* Prevent SDHCI core from writing reserved bits (e.g. HISPD). */
+	if (reg == SDHCI_HOST_CONTROL)
+		val &= ~ESDHC_HOST_CONTROL_RES;
+
 	clrsetbits_be32(host->ioaddr + base , 0xff << shift, val << shift);
 }
 
-- 
1.6.3.3



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