USB: make urb scatter-gather support more generic
The WHCI HCD will also support urbs with scatter-gather lists. Add a
usb_bus field to indicated how many sg list elements are supported by
the HCD. Use this to decide whether to pass the scatter-list to the HCD
or not.
Make the usb-storage driver use this new field.
Signed-off-by: David Vrabel <david.vrabel@csr.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index 01e43a1..1599d86 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -843,6 +843,15 @@
complete_and_exit(&us->scanning_done, 0);
}
+static unsigned int usb_stor_sg_tablesize(struct usb_interface *intf)
+{
+ struct usb_device *usb_dev = interface_to_usbdev(intf);
+
+ if (usb_dev->bus->sg_tablesize) {
+ return usb_dev->bus->sg_tablesize;
+ }
+ return SG_ALL;
+}
/* First part of general USB mass-storage probing */
int usb_stor_probe1(struct us_data **pus,
@@ -871,6 +880,7 @@
* Allow 16-byte CDBs and thus > 2TB
*/
host->max_cmd_len = 16;
+ host->sg_tablesize = usb_stor_sg_tablesize(intf);
*pus = us = host_to_us(host);
memset(us, 0, sizeof(struct us_data));
mutex_init(&(us->dev_mutex));