Re: [PATCH] HID: sony: disable descriptor fixup for FutureMax Dance Mat

On Mon, 25 Jul 2016 11:14:04 +0200
Benjamin Tissoires [off-list ref] wrote:

On Jul 21 2016 or thereabouts, Antonio Ospite wrote:

[...]

quoted

It would be interesting to understand why some (supposedly) compatible
devices break, maybe they rely on the fact that the PS3 would use the
original report?

[just speculating]
I would be *really* surprised if the Sony software were to overwrite the
report descriptor of their own sony controllers. My guess is that their
HID stack or their Playstation driver is compatible with the original
report descriptors and so they can handle the differences between
original and weirdo controllers.

That's basically what I was thinking too, in my last sentence I meant
to write report _descriptor_ :)

Mikko, if you have some time, could you post the original report
descriptor for your device?

$ hexdump /sys/bus/hid/devices/XXXX\:YYYY\:ZZZZ.0001/report_descriptor

or

$ hidrd-convert -i natv -o code /sys/bus/hid/devices/XXXX\:YYYY\:ZZZZ.0001/report_descriptor

You can also find out the length of the raw output report with trial and
error, start with a line like this:

$ sudo hexdump -v -e '49/1 "%02x " "\n"' /dev/hidraw0

and increase/decrease the value (49 works with original controllers)
until you see a regular pattern when comparing lines.

Anyways this is just for curiosity, we are not going to spend too much
time on that... or are we? :)

Thanks,
   Antonio

-- 
Antonio Ospite
http://ao2.it

A: Because it messes up the order in which people normally read text.
   See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?