Input: HIDDEV - make HIDIOCSREPORT wait IO completion

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@kontron.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/usb/input/hiddev.c b/drivers/usb/input/hiddev.c
index 4c13331b5f4..d32427818af 100644
--- a/drivers/usb/input/hiddev.c
+++ b/drivers/usb/input/hiddev.c
@@ -507,6 +507,7 @@ static int hiddev_ioctl(struct inode *inode, struct file *file, unsigned int cmd
                         return -EINVAL;
 
                 hid_submit_report(hid, report, USB_DIR_OUT);
+                hid_wait_io(hid);
 
                 return 0;