Messages in this thread | | | Date | Fri, 7 Mar 2014 10:18:15 -0500 (EST) | From | Alan Stern <> | Subject | RE: [PATCH 2/2] Revert "USBNET: ax88179_178a: enable tso if usb host supports sg dma" |
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On Fri, 7 Mar 2014, David Laight wrote:
> From: Mathias Nyman > > This reverts commit 3804fad45411b48233b48003e33a78f290d227c8. > > > > This commit, together with commit 247bf557273dd775505fb9240d2d152f4f20d304 > > "xhci 1.0: Limit arbitrarily-aligned scatter gather." 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. > > This patch doesn't need to be reverted.
Yes, it does.
> Provided the xhci driver doesn't set the flag to say that arbitrary scatter > gather is supported (ie usb_device_no_sg_constraint(dev->udev)) is false) > the ax88179_178a driver won't request transmits that need fragmenting.
True. But xhci-hcd _will_ set the flag, because of patch 1 in this series. In other words, patch 1 makes patch 2 necessary.
Alan Stern
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