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usbdevfs: Use scatter-gather lists for large bulk transfers

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When using urb->transfer_buffer we need to allocate physical contiguous buffers
for the entire transfer, which is pretty much guaranteed to fail with large
transfers.

Currently userspace works around this by breaking large transfers into multiple
urbs. For large bulk transfers this leads to all kind of complications.

This patch makes it possible for userspace to reliable submit large bulk
transfers to scatter-gather capable host controllers in one go, by using a
scatterlist to break the transfer up in managable chunks.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hans de Goede
2012-07-04 09:18:03 +02:00
committed by Greg Kroah-Hartman
parent 19181bc50e
commit 3d97ff63f8
2 changed files with 122 additions and 31 deletions
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include/linux/usbdevice_fs.h
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@@ -129,6 +129,7 @@ struct usbdevfs_hub_portinfo {
#define USBDEVFS_CAP_ZERO_PACKET 0x01
#define USBDEVFS_CAP_BULK_CONTINUATION 0x02
#define USBDEVFS_CAP_NO_PACKET_SIZE_LIM 0x04
#define USBDEVFS_CAP_BULK_SCATTER_GATHER 0x08
#ifdef __KERNEL__
#ifdef CONFIG_COMPAT