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  1. 08 11月, 2013 1 次提交
  3. 04 11月, 2013 1 次提交
  5. 30 10月, 2013 3 次提交
  7. 21 10月, 2013 1 次提交
  9. 18 10月, 2013 1 次提交
    • N
      HID: Fix unit exponent parsing again · ad0e669b
      由 Nikolai Kondrashov 提交于 
      Revert some changes done in 77463838.

Revert all changes done in hidinput_calc_abs_res as it mistakingly used
"Unit" item exponent nibbles to affect resolution value. This wasn't
breaking resolution calculation of relevant axes of any existing
devices, though, as they have only one dimension to their units and thus
1 in the corresponding nible.

Revert to reading "Unit Exponent" item value as a signed integer in
hid_parser_global to fix reading specification-complying values. This
fixes resolution calculation of devices complying to the HID standard,
including Huion, KYE, Waltop and UC-Logic graphics tablets which have
their report descriptors fixed by the drivers.

Explanations follow.

There are two "unit exponents" in HID specification and it is important
not to mix them. One is the global "Unit Exponent" item and another is
nibble values in the global "Unit" item. See 6.2.2.7 Global Items.

The "Unit Exponent" value is just a signed integer and is used to scale
the integer resolution unit values, so fractions can be expressed.

The nibbles of "Unit" value are used to select the unit system (nibble
0), and presence of a particular basic unit type in the unit formula and
its *exponent* (or power, nibbles 1-6). And yes, the latter is in two
complement and zero means absence of the unit type.

Taking the representation example of (integer) joules from the
specification:

[mass(grams)][length(centimeters)^2][time(seconds)^-2] * 10^-7

the "Unit Exponent" would be -7 (or 0xF9, if stored as a byte) and the
"Unit" value would be 0xE121, signifying:

Nibble  Part        Value   Meaning
-----   ----        -----   -------
0       System      1       SI Linear
1       Length      2       Centimeters^2
2       Mass        1       Grams
3       Time        -2      Seconds^-2

To give the resolution in e.g. hundredth of joules the "Unit Exponent"
item value should have been -9.

See also the examples of "Unit" values for some common units in the same
chapter.

However, there is a common misunderstanding about the "Unit Exponent"
value encoding, where it is assumed to be stored the same as nibbles in
"Unit" item. This is most likely due to the specification being a bit
vague and overloading the term "unit exponent". This also was and still
is proliferated by the official "HID Descriptor Tool", which makes this
mistake and stores "Unit Exponent" as such. This format is also
mentioned in books such as "USB Complete" and in Microsoft's hardware
design guides.

As a result many devices currently on the market use this encoding and
so the driver should support them.
Signed-off-by: NNikolai Kondrashov <spbnick@gmail.com>
Acked-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
      ad0e669b
  11. 09 10月, 2013 2 次提交
  13. 07 10月, 2013 1 次提交
    • D
      HID: wiimote: fix FF deadlock · f50f9aab
      由 David Herrmann 提交于 
      The input core has an internal spinlock that is acquired during event
injection via input_event() and friends but also held during FF callbacks.
That means, there is no way to share a lock between event-injection and FF
handling. Unfortunately, this is what is required for wiimote state
tracking and what we do with state.lock and input->lock.

This deadlock can be triggered when using continuous data reporting and FF
on a wiimote device at the same time. I takes me at least 30m of
stress-testing to trigger it but users reported considerably shorter
times (http://bpaste.net/show/132504/) when using some gaming-console
emulators.

The real problem is that we have two copies of internal state, one in the
wiimote objects and the other in the input device. As the input-lock is
not supposed to be accessed from outside of input-core, we have no other
chance than offloading FF handling into a worker. This actually works
pretty nice and also allows to implictly merge fast rumble changes into a
single request.

Due to the 3-layered workers (rumble+queue+l2cap) this might reduce FF
responsiveness. Initial tests were fine so lets fix the race first and if
it turns out to be too slow we can always handle FF out-of-band and skip
the queue-worker.

Cc: <stable@vger.kernel.org> # 3.11+
Reported-by: Thomas Schneider
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
      f50f9aab
  15. 02 10月, 2013 2 次提交
  17. 30 9月, 2013 1 次提交
  19. 26 9月, 2013 1 次提交
    • D
      HID: uhid: allocate static minor · 19872d20
      由 David Herrmann 提交于 
      udev has this nice feature of creating "dead" /dev/<node> device-nodes if
it finds a devnode:<node> modalias. Once the node is accessed, the kernel
automatically loads the module that provides the node. However, this
requires udev to know the major:minor code to use for the node. This
feature was introduced by:

  commit 578454ff
  Author: Kay Sievers <kay.sievers@vrfy.org>
  Date:   Thu May 20 18:07:20 2010 +0200

      driver core: add devname module aliases to allow module on-demand auto-loading

However, uhid uses dynamic minor numbers so this doesn't actually work. We
need to load uhid to know which minor it's going to use.

Hence, allocate a static minor (just like uinput does) and we're good
to go.
Reported-by: NTom Gundersen <teg@jklm.no>
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
      19872d20
  21. 13 9月, 2013 11 次提交
  23. 08 9月, 2013 1 次提交
  25. 04 9月, 2013 12 次提交
  27. 02 9月, 2013 2 次提交