svn commit: r352555 - head/sys/dev/usb

[Hans Petter Selasky]

Author: hselasky
Date: Fri Sep 20 11:00:02 2019
New Revision: 352555
URL: https://svnweb.freebsd.org/changeset/base/352555

Log:
  Increase the maximum user-space buffer size from 256kBytes to 32MBytes for
  libusb. This is useful for speeding up large data transfers while reducing
  the interrupt rate.
  
  Found at:	EuroBSDcon 2019
  MFC after:	1 week
  Sponsored by:	Mellanox Technologies

Modified:
  head/sys/dev/usb/usb_ioctl.h

Modified: head/sys/dev/usb/usb_ioctl.h
==============================================================================
--- head/sys/dev/usb/usb_ioctl.h	Fri Sep 20 10:56:13 2019	(r352554)
+++ head/sys/dev/usb/usb_ioctl.h	Fri Sep 20 11:00:02 2019	(r352555)
@@ -224,7 +224,7 @@ struct usb_fs_uninit {
 } USB_IOCTL_STRUCT_ALIGN(1);
 
 struct usb_fs_open {
-#define	USB_FS_MAX_BUFSIZE (1 << 18)
+#define	USB_FS_MAX_BUFSIZE (1 << 25)	/* 32 MBytes */
 	uint32_t max_bufsize;
 #define	USB_FS_MAX_FRAMES		(1U << 12)
 #define	USB_FS_MAX_FRAMES_PRE_SCALE	(1U << 31)	/* for ISOCHRONOUS transfers */