Re: hidp_output_raw_report, HID_OUTPUT_REPORT and Sixaxis

On Tue, 30 Nov 2010 18:40:03 +0100
"pascal@pabr.org" [off-list ref] wrote:

Pascal, you were replying to linux-input only so some of the original
recipients missed your comments.

Antonio Ospite wrote:

quoted

+++ b/net/bluetooth/hidp/core.c
 	case HID_OUTPUT_REPORT:
-		report_type = HIDP_TRANS_DATA | HIDP_DATA_RTYPE_OUPUT;
+		report_type = HIDP_TRANS_SET_REPORT | HIDP_DATA_RTYPE_OUPUT;

quoted

Is it only the Sixaxis which needs the output report as a SET_REPORT
operation, or the change above is an actual fix?

My understanding of the Bluetooth HID Profile specification [1],
section 7.4.9, is that on the control channel DATA is only for
responding to an incoming GET_REPORT.  Since Linux is the HID
Host, it will probably never need to reply to a GET_REPORT.
So your patch looks good.

OK, I managed to study [1] a little bit, so yes, I also think my patch
is acceptable right now, but just because as you note in another
message hidp_output_raw_report() is relying only on the control channel.
In section 7.9.1 there's no mention of DATA for Output reports on the
Control channel (see also Figure 11: SET_ Flow Chart).

So I am resending it, it shouldn't hurt.

Note that usbhid_output_raw_report() seems to send OUTPUT
reports as USB interrupt messages and FEATURE reports as
USB SET_REPORT control messages, which makes sense too.
It would be nice if hidraw behaved the same over USB and
over Bluetooth.  Unfortunately I don't think you can drive
the sixaxis leds with DATA on the Bluetooth interrupt channel.

However, even if my patch gets is, Output reports on the Sixaxis will
stop working again as soon as someone implements the behavior you are
suggesting, that is:
  Feature Report -> SET_REPORT on the Control channel
  Output Report  -> DATA on the Interrupt channel

So I am going to submit the hidp_output_raw_report() override in
hid-sony.c as well, does this sound OK?

[1] http://www.bluetooth.com/Specification%20Documents/HID_SPEC_V10.pdf

Regards,
  Antonio

-- 
Antonio Ospite
http://ao2.it

PGP public key ID: 0x4553B001

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?