The write protection signal is absent on a board based upon Xilinx' Zynq
processor ("ZyBo"). This leads the kernel to think that the MicroSD card is
write protected, and causes a kernel panic during boot, as root fails to
mount RW.
This patch adds a quirk and an optional OF property, sdhci,wp-broken to
work around this issue.
Signed-off-by: Eli Billauer <eli.billauer@xxxxxxxxx>
---
Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++
drivers/mmc/host/sdhci-pltfm.c | 4 +++-
drivers/mmc/host/sdhci.c | 2 ++
include/linux/mmc/sdhci.h | 2 ++
4 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index 458b57f..a3aab97 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -21,6 +21,8 @@ Optional properties:
below for the case, when a GPIO is used for the CD line
- wp-inverted: when present, polarity on the WP line is inverted. See the note
below for the case, when a GPIO is used for the WP line
+- wp-broken: when present, no indication of write protection is available,
+ and write protection is assumed always off.
- max-frequency: maximum operating clock frequency
- no-1-8-v: when present, denotes that 1.8v card voltage is not supported on
this system, even if the controller claims it is.
diff --git a/drivers/mmc/host/sdhci-pltfm.c b/drivers/mmc/host/sdhci-pltfm.c
index bef250e..7b433a2 100644
--- a/drivers/mmc/host/sdhci-pltfm.c
+++ b/drivers/mmc/host/sdhci-pltfm.c
@@ -80,7 +80,9 @@ void sdhci_get_of_property(struct platform_device *pdev)
bus_width == 1))
host->quirks |= SDHCI_QUIRK_FORCE_1_BIT_DATA;
- if (sdhci_of_wp_inverted(np))
+ if (of_get_property(np, "sdhci,wp-broken", NULL))
+ host->quirks2 |= SDHCI_QUIRK2_BROKEN_WRITE_PROTECT;
+ else if (sdhci_of_wp_inverted(np))
host->quirks |= SDHCI_QUIRK_INVERTED_WRITE_PROTECT;
if (of_get_property(np, "broken-cd", NULL))
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 9ddef47..6c77f2e 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1657,6 +1657,8 @@ static int sdhci_check_ro(struct sdhci_host *host)
is_readonly = 0;
else if (host->ops->get_ro)
is_readonly = host->ops->get_ro(host);
+ else if (host->quirks2 & SDHCI_QUIRK2_BROKEN_WRITE_PROTECT)
+ is_readonly = 0;
else
is_readonly = !(sdhci_readl(host, SDHCI_PRESENT_STATE)
& SDHCI_WRITE_PROTECT);
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index 362927c4..0f6ef9d 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -100,6 +100,8 @@ struct sdhci_host {
#define SDHCI_QUIRK2_BROKEN_HOST_CONTROL (1<<5)
/* Controller does not support HS200 */
#define SDHCI_QUIRK2_BROKEN_HS200 (1<<6)
+/* There is no indication for write protection at all, assume RW */
+#define SDHCI_QUIRK2_BROKEN_WRITE_PROTECT (1<<7)
int irq; /* Device IRQ */
void __iomem *ioaddr; /* Mapped address */
--
1.7.2.3
--
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