This is a note to let you know that I've just added the patch titled
Revert "xhci 1.0: Limit arbitrarily-aligned scatter gather."
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From e2ed511400d41e0d136089d5a55ceab57c6a2426 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Date: Fri, 7 Mar 2014 17:06:57 +0200
Subject: Revert "xhci 1.0: Limit arbitrarily-aligned scatter gather."
This reverts commit 247bf557273dd775505fb9240d2d152f4f20d304.
This commit, together with commit 3804fad45411b48233b48003e33a78f290d227c8
"USBNET: ax88179_178a: enable tso if usb host supports sg dma" were
origially added to get xHCI 1.0 hosts and usb ethernet ax88179_178a devices
working together with scatter gather. xHCI 1.0 hosts pose some requirement on how transfer
buffers are aligned, setting this requirement for 1.0 hosts caused USB 3.0 mass
storage devices to fail more frequently.
USB 3.0 mass storage devices used to work before 3.14-rc1. Theoretically,
the TD fragment rules could have caused an occasional disk glitch.
Now the devices *will* fail, instead of theoretically failing.
>From a user perspective, this looks like a regression; the USB device obviously
fails on 3.14-rc1, and may sometimes silently fail on prior kernels.
The proper soluition is to implement the TD fragment rules required, but for now
this patch needs to be reverted to get USB 3.0 mass storage devices working at the
level they used to.
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 6fe577d46fa2..924a6ccdb622 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4733,6 +4733,9 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
/* Accept arbitrarily long scatter-gather lists */
hcd->self.sg_tablesize = ~0;
+ /* support to build packet from discontinuous buffers */
+ hcd->self.no_sg_constraint = 1;
+
/* XHCI controllers don't stop the ep queue on short packets :| */
hcd->self.no_stop_on_short = 1;
@@ -4757,14 +4760,6 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
/* xHCI private pointer was set in xhci_pci_probe for the second
* registered roothub.
*/
- xhci = hcd_to_xhci(hcd);
- /*
- * Support arbitrarily aligned sg-list entries on hosts without
- * TD fragment rules (which are currently unsupported).
- */
- if (xhci->hci_version < 0x100)
- hcd->self.no_sg_constraint = 1;
-
return 0;
}
@@ -4793,9 +4788,6 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
if (xhci->hci_version > 0x96)
xhci->quirks |= XHCI_SPURIOUS_SUCCESS;
- if (xhci->hci_version < 0x100)
- hcd->self.no_sg_constraint = 1;
-
/* Make sure the HC is halted. */
retval = xhci_halt(xhci);
if (retval)
--
1.9.0
--
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