[PATCH 3.12 59/82] Revert "xhci: Set scatter-gather limit to avoid failed block writes."

[Greg Kroah-Hartman]

3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>

commit 1386ff75797a187df324062fb4e929152392da88 upstream.

This reverts commit f2d9b991c549f159dc9ae81f77d8206c790cbfee.

We are ripping out commit 35773dac5f862cb1c82ea151eba3e2f6de51ec3e "usb:
xhci: Link TRB must not occur within a USB payload burst" because it's a
hack that caused regressions in the usb-storage and userspace USB
drivers that use usbfs and libusb.  This commit attempted to fix the
issues with that patch.

Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci.c |    4 ++--
 drivers/usb/host/xhci.h |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4727,8 +4727,8 @@ int xhci_gen_setup(struct usb_hcd *hcd,
 	struct device		*dev = hcd->self.controller;
 	int			retval;
 
-	/* Limit the block layer scatter-gather lists to half a segment. */
-	hcd->self.sg_tablesize = TRBS_PER_SEGMENT / 2;
+	/* Accept arbitrarily long scatter-gather lists */
+	hcd->self.sg_tablesize = ~0;
 
 	/* XHCI controllers don't stop the ep queue on short packets :| */
 	hcd->self.no_stop_on_short = 1;
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1262,7 +1262,7 @@ union xhci_trb {
  * since the command ring is 64-byte aligned.
  * It must also be greater than 16.
  */
-#define TRBS_PER_SEGMENT	256
+#define TRBS_PER_SEGMENT	64
 /* Allow two commands + a link TRB, along with any reserved command TRBs */
 #define MAX_RSVD_CMD_TRBS	(TRBS_PER_SEGMENT - 3)
 #define TRB_SEGMENT_SIZE	(TRBS_PER_SEGMENT*16)


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