[PATCH] hiddev: output reports are dropped when HIDIOCSREPORT iscalled in short succession

[Stefan Nickl]

Hi,

when trying to make the hiddev driver issue several Set_Report control
transfers to a custom device with 2.6.13-rc6, only the first transfer in
a row is carried out, while others immediately following it are silently
dropped.

This happens where hid_submit_report() (in hid-core.c) tests for
HID_CTRL_RUNNING, which seems to be still set because the first transfer
is not finished yet.

As a workaround, inserting a delay between the two calls to
ioctl(HIDIOCSREPORT) in userspace "solves" the problem.
The straightforward fix is to add a call to hid_wait_io() to the
implementation of HIDIOCSREPORT (in hiddev.c), just like for
HIDIOCGREPORT. Works fine for me.

Apparently, this issue has some history:
http://marc.theaimsgroup.com/?l=linux-usb-users&m=111100670105558&w=2

Signed-off-by: Stefan Nickl <Stefan.Nickl@xxxxxxxxxxx>

-- 
Stefan Nickl
Kontron Modular Computers

--- v2.6.13-rc6/drivers/usb/input/hiddev.c.orig	2005-08-22 10:56:55.000000000 +0200
+++ v2.6.13-rc6/drivers/usb/input/hiddev.c	2005-08-22 10:57:07.000000000 +0200
@@ -507,6 +507,7 @@ static int hiddev_ioctl(struct inode *in
 			return -EINVAL;
 
 		hid_submit_report(hid, report, USB_DIR_OUT);
+		hid_wait_io(hid);
 
 		return 0;