Hello all,

On Mon, Mar 26, 2012 at 5:20 PM, David Herrmann
[off-list ref] wrote:

Hi

This is the second revision of the UHID driver. It basically allows to re=

gister

hid_ll_drivers in user-space. This is needed to implement Bluetooth HoG (=

HID

over GATT) as discussed earlier.

We have a first prototype implementation of the HoG plugin working
with the uhid driver \o/

I'll send a RFC to the linux-bluetooth mailing list later, but I think
it's nice to give some feedback on the uhid module here as well.

The only problem I've encountered while testing it was that it doesn't
seem to work if I set the 'bus' field on the struct uhid_create_req to
BUS_BLUETOOTH. Initially I thought this was just metadata, but
changing it to BUS_USB makes it work.

Additionally, I don't know if you forgot or did it on purpose, but you
didn't add the uhid example to samples/Kconfig and sample/Makefile.

Changes:
=C2=A0- Improved documentation
=C2=A0- Added example which emulates a 3-button mouse with wheel in user-=

space

I've (partially) tested the example, on a X-less virtual machine. I'll
try it on a box with X so I can attach the virtual mouse to a pointer
in X and see the cursor moving.

=C2=A0- Fixed some remaining bugs

I didn't change any major parts. I checked that writev/readv work correct=

ly and

I documented how to use it in ./Documentation/hid/uhid.txt.

For a full example please see ./samples/uhid/uhid-example.c.

While developing it I also considered moving HIDP to user-space. If we do=

 BT-HoG

in user-space, it should be easier to also move HIDP to user-space. The c=

urrent

in-kernel HIDP is buggy, anyway.

Still open points:
=C2=A0- How do I get a proper "parent" pointer for uhid->hid->dev.parent?=

 I could use

=C2=A0 the uhid misc device as parent or is there some device-struct insi=

de "struct

=C2=A0 file"?
=C2=A0- Should user-space be able to provide "uniq" and "phys" names for =

HID-devices?

=C2=A0- uhid_event is quite big (>4KB) which makes uhid_device really big=

 (~70KB).

=C2=A0 Should I allocate the ring-buffer dynamically to avoid this?
=C2=A0- Should I provide the quirks field to user-space? Probably as part=

 of

=C2=A0 UHID_START?
=C2=A0- Could someone review x32 COMPAT stuff? I tried to align all the p=

ublic

=C2=A0 structures correctly so I could even remove the __packed attribute=

. Anyway, I

=C2=A0 thought keeping it is probably better for future extensions.

I spent some time on the locks and they seem all fine. I couldn't find an=

y

races.

Jiri, Marcel, could you review the design and tell me what you think?

A short notice about the protocol:
User-space is allowed to send only as much data as is needed for the even=

t. That

is, when sending the UHID_DESTROY event (which has no payload) it would b=

e

actually enough to only send a __u32 field (ev->type) with write().
This is not to speed up the write()s or read()s but rather to allow exten=

ding

the uhid_event structure in the future. We can actually add arbitrary ext=

ra

event-types and still keep ABI compatibility. Therefore, I thought of add=

ing an

"uhid_version" field to UHID_CREATE so user-space can define what UHID pr=

otocol

it is using.

Regards
David

David Herrmann (1):
=C2=A0HID: User-space I/O driver support for HID subsystem

=C2=A0Documentation/hid/uhid.txt =C2=A0| =C2=A0152 ++++++++++++++
=C2=A0drivers/hid/Kconfig =C2=A0 =C2=A0 =C2=A0 =C2=A0 | =C2=A0 21 ++
=C2=A0drivers/hid/Makefile =C2=A0 =C2=A0 =C2=A0 =C2=A0| =C2=A0 =C2=A02 +-
=C2=A0drivers/hid/uhid.c =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0| =C2=A0473 ++=

+++++++++++++++++++++++++++++++++++++++++

=C2=A0include/linux/Kbuild =C2=A0 =C2=A0 =C2=A0 =C2=A0| =C2=A0 =C2=A01 +
=C2=A0include/linux/uhid.h =C2=A0 =C2=A0 =C2=A0 =C2=A0| =C2=A0 84 +++++++=

+

=C2=A0samples/uhid/Makefile =C2=A0 =C2=A0 =C2=A0 | =C2=A0 10 +
=C2=A0samples/uhid/uhid-example.c | =C2=A0381 +++++++++++++++++++++++++++=

+++++++

=C2=A08 files changed, 1123 insertions(+), 1 deletion(-)
=C2=A0create mode 100644 Documentation/hid/uhid.txt
=C2=A0create mode 100644 drivers/hid/uhid.c
=C2=A0create mode 100644 include/linux/uhid.h
=C2=A0create mode 100644 samples/uhid/Makefile
=C2=A0create mode 100644 samples/uhid/uhid-example.c

--
1.7.9.4

--=20
Jo=C3=A3o Paulo Rechi Vita
Openbossa Labs - INdT