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Subject[PATCH] incrase usbdevfs bulk buffer size
Increase the usbdevfs buffer size limit.

I hit this limit with running ehci in the VM. The a single ehci
qTD transfer buffer can be 5 pages long, that is 20K. The current devio bulk
transfer limit is 16K. I am not sure why the bulk transfer limit
is 16K. I can complicate the user space part to work around that,
but it seems much simpler just allow usbdevfs to accept bigger buffers.

I did some limited usage test with ehci controller. It seems works for me,
it did use a bigger buffer and nothing blow up.

Signed-Off-By: Christopher Li <>

Index: linux-
--- linux- 2005-09-28 13:08:10.000000000 -0700
+++ linux- 2005-10-01 04:58:47.000000000 -0700
@@ -72,7 +72,7 @@ MODULE_PARM_DESC (usbfs_snoop, "true to
} while (0)

-#define MAX_USBFS_BUFFER_SIZE 16384
+#define MAX_USBFS_BUFFER_SIZE (32*1024)

static inline int connected (struct usb_device *dev)
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