can: mcba_usb: Fix termination command argument
authorYasushi SHOJI <yasushi.shoji@gmail.com>
Thu, 24 Nov 2022 15:25:03 +0000 (00:25 +0900)
committerMarc Kleine-Budde <mkl@pengutronix.de>
Thu, 24 Nov 2022 15:26:48 +0000 (16:26 +0100)
commit1a8e3bd25f1e789c8154e11ea24dc3ec5a4c1da0
treeaebc8cdd274f488a9a8a76d093cbbbc1d49a94da
parent68b4f9e0bdd0f920d7303d07bfe226cd0976961d
can: mcba_usb: Fix termination command argument

Microchip USB Analyzer can activate the internal termination resistors
by setting the "termination" option ON, or OFF to to deactivate them.
As I've observed, both with my oscilloscope and captured USB packets
below, you must send "0" to turn it ON, and "1" to turn it OFF.

From the schematics in the user's guide, I can confirm that you must
drive the CAN_RES signal LOW "0" to activate the resistors.

Reverse the argument value of usb_msg.termination to fix this.

These are the two commands sequence, ON then OFF.

> No.     Time           Source                Destination           Protocol Length Info
>       1 0.000000       host                  1.3.1                 USB      46     URB_BULK out
>
> Frame 1: 46 bytes on wire (368 bits), 46 bytes captured (368 bits)
> USB URB
> Leftover Capture Data: a80000000000000000000000000000000000a8
>
> No.     Time           Source                Destination           Protocol Length Info
>       2 4.372547       host                  1.3.1                 USB      46     URB_BULK out
>
> Frame 2: 46 bytes on wire (368 bits), 46 bytes captured (368 bits)
> USB URB
> Leftover Capture Data: a80100000000000000000000000000000000a9

Signed-off-by: Yasushi SHOJI <yashi@spacecubics.com>
Link: https://lore.kernel.org/all/20221124152504.125994-1-yashi@spacecubics.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
drivers/net/can/usb/mcba_usb.c