[MMC] sdhci: more DMA capabilities tests

Properly test for controller interface to see if it's DMA capable.  As many
controllers are misconfigured in this regard, also add debug parameters to
force DMA support either way.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 29 insertions, 1 deletions

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 06dec744d53e..315ab49e4b2c 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -28,6 +28,9 @@
 #define DBG(f, x...) \
         pr_debug(DRIVER_NAME " [%s()]: " f, __func__,## x)
 
+static unsigned int debug_nodma = 0;
+static unsigned int debug_forcedma = 0;
+
 static const struct pci_device_id pci_ids[] __devinitdata = {
         /* handle any SD host controller */
         {PCI_DEVICE_CLASS((PCI_CLASS_SYSTEM_SDHCI << 8), 0xFFFF00)},
@@ -1105,6 +1108,16 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot)
                 return -ENODEV;
         }
 
+        if ((pdev->class & 0x0000FF) == PCI_SDHCI_IFVENDOR) {
+                printk(KERN_ERR DRIVER_NAME ": Vendor specific interface. Aborting.\n");
+                return -ENODEV;
+        }
+
+        if ((pdev->class & 0x0000FF) > PCI_SDHCI_IFVENDOR) {
+                printk(KERN_ERR DRIVER_NAME ": Unknown interface. Aborting.\n");
+                return -ENODEV;
+        }
+
         mmc = mmc_alloc_host(sizeof(struct sdhci_host), &pdev->dev);
         if (!mmc)
                 return -ENOMEM;
@@ -1146,7 +1159,16 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot)
 
         caps = readl(host->ioaddr + SDHCI_CAPABILITIES);
 
-        if ((caps & SDHCI_CAN_DO_DMA) && ((pdev->class & 0x0000FF) == 0x01))
+        if (debug_nodma)
+                DBG("DMA forced off\n");
+        else if (debug_forcedma) {
+                DBG("DMA forced on\n");
+                host->flags |= SDHCI_USE_DMA;
+        } else if ((pdev->class & 0x0000FF) != PCI_SDHCI_IFDMA)
+                DBG("Controller doesn't have DMA interface\n");
+        else if (!(caps & SDHCI_CAN_DO_DMA))
+                DBG("Controller doesn't have DMA capability\n");
+        else
                 host->flags |= SDHCI_USE_DMA;
 
         if (host->flags & SDHCI_USE_DMA) {
@@ -1429,7 +1451,13 @@ static void __exit sdhci_drv_exit(void)
 module_init(sdhci_drv_init);
 module_exit(sdhci_drv_exit);
 
+module_param(debug_nodma, uint, 0444);
+module_param(debug_forcedma, uint, 0444);
+
 MODULE_AUTHOR("Pierre Ossman <drzeus@drzeus.cx>");
 MODULE_DESCRIPTION("Secure Digital Host Controller Interface driver");
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL");
+
+MODULE_PARM_DESC(debug_nodma, "Forcefully disable DMA transfers. (default 0)");
+MODULE_PARM_DESC(debug_forcedma, "Forcefully enable DMA transfers. (default 0)");