diff options
| -rw-r--r-- | drivers/usb/storage/uas.c | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index e0133c9ab0bf..e34c75970ed1 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; |