From: Stefan Nickl 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 Signed-off-by: Andrew Morton --- drivers/usb/input/hiddev.c | 1 + 1 files changed, 1 insertion(+) diff -puN drivers/usb/input/hiddev.c~hiddev-output-reports-are-dropped-when-hidiocsreport-is drivers/usb/input/hiddev.c --- devel/drivers/usb/input/hiddev.c~hiddev-output-reports-are-dropped-when-hidiocsreport-is 2005-08-22 21:52:01.000000000 -0700 +++ devel-akpm/drivers/usb/input/hiddev.c 2005-08-22 21:52:01.000000000 -0700 @@ -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; _