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mmc: sdhci: add quirk for broken write protect detection

PATCH Superseded Eli Billauer 3 participants 4 messages Feb 24, 2014 – Nov 27, 2014

Subsystems (3)
Device tree bindings MMC, SD and SDIO Secure digital host controller interface (SDHCI) driver

v1 of 2 Superseded Latest is v2 →

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Eli Billauer

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#0 lore raw

PATCH 1/1 mmc: sdhci: add quirk for broken write protect detection

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 <[email protected]>
---
 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(-)
Documentation/devicetree/bindings/mmc/mmc.txt +2 -0
index 458b57f..a3aab97 100644
@@ -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.
drivers/mmc/host/sdhci-pltfm.c +3 -1
index bef250e..7b433a2 100644
@@ -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))
drivers/mmc/host/sdhci.c +2 -0
index 9ddef47..6c77f2e 100644
@@ -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);
include/linux/mmc/sdhci.h +2 -0
index 362927c4..0f6ef9d 100644
@@ -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 */
Signature · 1 line
1.7.2.3
#1 lore raw

Hi Eli,

Quoted 7 lines · Eli Billauer

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.

Just to confirm your motivation for the patch: wp-inverted would solve this problem for you, but you'd rather add a new property that more accurately describes the hardware?

(We'd probably use broken-wp, for symmetry with the existing broken-cd.)

Thanks,

- Chris.

Signature · 1 line
Chris Ball   <[email protected]>   <http://printf.net/>
author
#2 lore raw

Hello Chris.

Quoted 9 lines · Chris Ball

Hi Eli,

Quoted 5 lines · Eli Billauer

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.

Quoted 7 lines
Quoted 3 lines

This patch adds a quirk and an optional OF property, sdhci,wp-broken to work around this issue.

Just to confirm your motivation for the patch: wp-inverted would solve this problem for you, but you'd rather add a new property that more accurately describes the hardware?

Yes, that's the point.

Quoted 2 lines

(We'd probably use broken-wp, for symmetry with the existing broken-cd.)

I picked "sdhci,wp-broken" because of the similarity with "sdhci,wp-inverted", as opposed to "broken-cd" (with no "sdhci," prefix).

Would you like me to resubmit the patch with "broken-wp"? Or maybe "sdhci,broken-wp"?

Regards,
Eli

#3 lore raw
In reply to Eli Billauer
Quoted 8 lines · Eli Billauer <eli.billauer <at> gmail.com> writes:

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.

Hello, I am hitting the issue described in this thread, where can I get the patch or the repo to fic it?