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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2012-01-11 12:42:32 +0100
committerSarah Sharp <sarah.a.sharp@linux.intel.com>2012-02-02 14:51:00 -0800
commitc898add51c7b5b99fcecdeaf4df2ca30949cacb6 (patch)
tree592270c089abd5c93b08ebfe7f85882ab28946f7 /drivers/usb/storage
parentb603669842b3b2c66a1fc2e926f35a2143be8b3b (diff)
usb/uas: only bind if the hcd supports SG
The UAS driver requires SG support by the HCD operating the device. This patch stops UAS from operating on a HCD without sg support and prints a message to let him know. The spec says: |For [USB2] backward compatibility, the device shall present [BOT] as |alternate interface zero (primary) and [UAS] as alternate interface one |(secondary). A device which does not need backward compatibility with |[BOT] shall present [UAS] as alternate interface zero. In [USB2] |systems, the [BOT] driver or an associated filter driver may need to |issue a SET INTERFACE request for alternate interface one and then allow |the [UAS] driver to load. If the user used usb_modeswitch to switch to UAS then he can go back to BOT or use a different HCD. In case UAS is the only interface then there is currently no way out. In future usb_sg_wait() should be extended to provide a non-blocking interface so it can work with the UAS driver. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Diffstat (limited to 'drivers/usb/storage')
-rw-r--r--drivers/usb/storage/uas.c25
1 files changed, 19 insertions, 6 deletions
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index e0133c9ab0b..e34c75970ed 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -13,6 +13,7 @@
#include <linux/types.h>
#include <linux/module.h>
#include <linux/usb.h>
+#include <linux/usb/hcd.h>
#include <linux/usb/storage.h>
#include <scsi/scsi.h>
@@ -621,22 +622,34 @@ static int uas_is_interface(struct usb_host_interface *intf)
intf->desc.bInterfaceProtocol == USB_PR_UAS);
}
+static int uas_isnt_supported(struct usb_device *udev)
+{
+ struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+
+ dev_warn(&udev->dev, "The driver for the USB controller %s does not "
+ "support scatter-gather which is\n",
+ hcd->driver->description);
+ dev_warn(&udev->dev, "required by the UAS driver. Please try an"
+ "alternative USB controller if you wish to use UAS.\n");
+ return -ENODEV;
+}
+
static int uas_switch_interface(struct usb_device *udev,
struct usb_interface *intf)
{
int i;
-
- if (uas_is_interface(intf->cur_altsetting))
- return 0;
+ int sg_supported = udev->bus->sg_tablesize != 0;
for (i = 0; i < intf->num_altsetting; i++) {
struct usb_host_interface *alt = &intf->altsetting[i];
- if (alt == intf->cur_altsetting)
- continue;
- if (uas_is_interface(alt))
+
+ if (uas_is_interface(alt)) {
+ if (!sg_supported)
+ return uas_isnt_supported(udev);
return usb_set_interface(udev,
alt->desc.bInterfaceNumber,
alt->desc.bAlternateSetting);
+ }
}
return -ENODEV;