HID: core: fix computation of the report size
authorBenjamin Tissoires <benjamin.tissoires@redhat.com>
Wed, 30 Apr 2014 21:48:40 +0000 (17:48 -0400)
committerJiri Kosina <jkosina@suse.cz>
Mon, 5 May 2014 13:54:40 +0000 (15:54 +0200)
commit19e4ec525b37cdecbdb4f86edaae7f56a67339ee
tree09ff821bfc4f821fd900a01da3b8e5eb6147d3a2
parent7c7606a2464fee1cf50efef34aa44aee1edf453a
HID: core: fix computation of the report size

The extra seven bits are only required when allocating the report buffer.
We can not use those extra bytes for the length of the report in the
generic implementation of .request because the device might (will) refuse
the set_report command.
This has been verified on the Atmel touchpad found on the Samsung Ativ 9
plus, which uses hid-multitouch and HID over I2C. Without this fix, the
device refuses to switch to the multitouch mode, and it becomes unresponsive
from the user point of view.

Actually, this has been discussed during the initial submission of the
commit 4fa5a7f76cc7b6ac87f57741edd2b124851d119f, see
https://patchwork.kernel.org/patch/3621751/

Unfortunately, I completely forgot about it later.

Reported-by: Matthias Bayer <thematthiasbayer@gmail.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
drivers/hid/hid-core.c