Some board designs for embedded systems  do not always bring up the SD Host 
Write Protect Signal.  
This patch defines a new quirk that when enabled enables write access.

>From 032242c62e0fe22eb6f5a4e0311eaab67ef54cbe Mon Sep 17 00:00:00 2001
From: Philip Rakity <prak...@marvell.com>
Date: Sun, 19 Sep 2010 14:34:02 -0700
Subject: [PATCH] sdhci: add quirk for controllers that don't support write only 
detect
 Signed-off-by: Philip Rakity <prak...@marvell.com>

---
 drivers/mmc/host/sdhci.c |    2 ++
 drivers/mmc/host/sdhci.h |    2 ++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 401527d..e2b1f32 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1213,6 +1213,8 @@ static int sdhci_get_ro(struct mmc_host *mmc)
 
        if (host->flags & SDHCI_DEVICE_DEAD)
                present = 0;
+       else if (host->quirks & SDHCI_NO_SUPPORT_FOR_WRITE_PROTECT)
+               present = SDHCI_WRITE_PROTECT;
        else
                present = sdhci_readl(host, SDHCI_PRESENT_STATE);
 
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index d316bc7..290b5a8 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -247,6 +247,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12             (1<<28)
 /* Controller doesn't have HISPD bit field in HI-SPEED SD card */
 #define SDHCI_QUIRK_NO_HISPD_BIT                       (1<<29)
+/* Controller does not have write protect signal               */
+#define SDHCI_NO_SUPPORT_FOR_WRITE_PROTECT             (1<<30)
 
        int                     irq;            /* Device IRQ */
        void __iomem *          ioaddr;         /* Mapped address */
-- 
1.6.0.4
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