mmc: sdhci: Fix read-only detection with JMicron 388 chip

On HP laptops with JMicron 388 chip, the write-locked SD card isn't
detected correctly as read-only in many cases.  This is because the
PRESENT_STATE register becomes unsable just after plugging, and it
returns the WRITE_PROTECT bit wrongly at the first read.

This patch fixes the read-only detection by adding a new sdhci quirk
indicating to check the register more intensively with a relatively
long delay.

The patch is tested with 2.6.39-rc4 kernel.

Cc: Aries Lee <arieslee@jmicron.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Chris Ball <cjb@laptop.org>

3 files changed, 31 insertions, 4 deletions

diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
index 82c5dc412679..936bbca19c0a 100644
--- a/drivers/mmc/host/sdhci-pci.c
+++ b/drivers/mmc/host/sdhci-pci.c
@@ -327,6 +327,11 @@ static int jmicron_probe(struct sdhci_pci_chip *chip)
                 return ret;
         }
 
+        /* quirk for unsable RO-detection on JM388 chips */
+        if (chip->pdev->device == PCI_DEVICE_ID_JMICRON_JMB388_SD ||
+            chip->pdev->device == PCI_DEVICE_ID_JMICRON_JMB388_ESD)
+                chip->quirks |= SDHCI_QUIRK_UNSTABLE_RO_DETECT;
+
         return 0;
 }
 
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a70a3d1ef35a..e5cfe70dc23b 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1256,14 +1256,11 @@ out:
         spin_unlock_irqrestore(&host->lock, flags);
 }
 
-static int sdhci_get_ro(struct mmc_host *mmc)
+static int check_ro(struct sdhci_host *host)
 {
-        struct sdhci_host *host;
         unsigned long flags;
         int is_readonly;
 
-        host = mmc_priv(mmc);
-
         spin_lock_irqsave(&host->lock, flags);
 
         if (host->flags & SDHCI_DEVICE_DEAD)
@@ -1281,6 +1278,29 @@ static int sdhci_get_ro(struct mmc_host *mmc)
                 !is_readonly : is_readonly;
 }
 
+#define SAMPLE_COUNT    5
+
+static int sdhci_get_ro(struct mmc_host *mmc)
+{
+        struct sdhci_host *host;
+        int i, ro_count;
+
+        host = mmc_priv(mmc);
+
+        if (!(host->quirks & SDHCI_QUIRK_UNSTABLE_RO_DETECT))
+                return check_ro(host);
+
+        ro_count = 0;
+        for (i = 0; i < SAMPLE_COUNT; i++) {
+                if (check_ro(host)) {
+                        if (++ro_count > SAMPLE_COUNT / 2)
+                                return 1;
+                }
+                msleep(30);
+        }
+        return 0;
+}
+
 static void sdhci_enable_sdio_irq(struct mmc_host *mmc, int enable)
 {
         struct sdhci_host *host;
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index 83bd9f76709a..92e1c9ad126c 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -85,6 +85,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_NO_HISPD_BIT                        (1<<29)
 /* Controller treats ADMA descriptors with length 0000h incorrectly */
 #define SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC            (1<<30)
+/* The read-only detection via SDHCI_PRESENT_STATE register is unstable */
+#define SDHCI_QUIRK_UNSTABLE_RO_DETECT                  (1<<31)
 
         int irq;                /* Device IRQ */
         void __iomem *ioaddr;   /* Mapped address */