Thread (4 messages) 4 messages, 4 authors, 2011-02-22

Re: [PATCH 2/2] bt hidp: send Output reports using SET_REPORT on the Control channel

From: Gustavo F. Padovan <hidden>
Date: 2011-02-21 21:08:34
Also in: linux-bluetooth

Possibly related (same subject, not in this thread)

Hi Jiri,

* Jiri Kosina [off-list ref] [2011-02-21 13:50:40 +0100]:
On Sun, 20 Feb 2011, Alan Ott wrote:
quoted
On 02/20/2011 12:26 PM, Antonio Ospite wrote:
quoted
The current implementation of hidp_output_raw_report() relies only on
the Control channel even for Output reports, and the BT HID
specification [1] does not mention using the DATA message for Output
reports on the Control channel (see section 7.9.1 and also Figure 11:
SET_ Flow Chart), so let us just use SET_REPORT.

This also fixes sending Output reports to some devices (like Sony
Sixaxis) which are not able to handle DATA messages on the Control
channel.

Ideally hidp_output_raw_report() could be improved to use this scheme:
   Feature Report -- SET_REPORT on the Control channel
   Output Report  -- DATA on the Interrupt channel
for more efficiency, but as said above, right now only the Control
channel is used.

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

  	case HID_OUTPUT_REPORT:
-		report_type = HIDP_TRANS_DATA | HIDP_DATA_RTYPE_OUPUT;
+		report_type = HIDP_TRANS_SET_REPORT | HIDP_DATA_RTYPE_OUPUT;
   
I think this is right. Section 7.4[.0] says that SET_ and GET_ requests return
with HANDSHAKE. Section 7.4.9 says that DATA does _not_ return a HANDSHAKE. My
patch to hidp_output_raw_report() relies on getting a HANDSHAKE back, so it
wouldn't have worked with BT devices that take output reports. Since I don't
have any that do, I couldn't test it. (And it was like that when I got here :)
)

For the whole set:
Acked-by: Alan Ott <redacted>
Agreed.

As an author of the original code, I agree with the change. But as it is 
in net/bluetooth, I'd at least have Acked-by from some of the Bluetooth 
folks before I take it through my tree.

Marcel? Gustavo?
Acked-by: Gustavo F. Padovan <redacted>

-- 
Gustavo F. Padovan
http://profusion.mobi
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