RE: [PATCH v2 3/3] can: gs_usb: add switchable termination support

["Trevitz, Daniel" <Daniel.Trevitz@wika.com>]

Marc,

+       if (feature & GS_CAN_FEATURE_TERMINATION) {
+               dev->can.termination_const = gs_usb_termination_const;
+               dev->can.termination_const_cnt = ARRAY_SIZE(gs_usb_termination_const);
+               dev->can.do_set_termination = gs_usb_set_termination;
+
+               rc = gs_usb_get_termination(netdev, &dev->can.termination);
+               if (rc) {
+                       dev_err(&intf->dev,
+                               "Couldn't get current termination state for channel %d (%pe)\n",
+                               channel, ERR_PTR(rc));
+                       goto out_free_candev;
+               }
+       }

Does it make sense to check if we have the termination support, then set the values?
My logic is that just because the termination is not working correctly, it does not mean everything is broken.
This way you could have a multi-can-channel USB device but with only specific channels supporting configurable termination resistors.

Something like:

rc = gs_usb_get_termination(netdev, &dev->can.termination);
 if (rc) {
	dev_err(&intf->dev,
		"Couldn't get current termination state for channel %d (%pe). Not enabling termination support for this channel\n",
		channel, ERR_PTR(rc));
 } else {
	dev->can.termination_const = gs_usb_termination_const;
	dev->can.termination_const_cnt = ARRAY_SIZE(gs_usb_termination_const);
	dev->can.do_set_termination = gs_usb_set_termination;
}

BR,
  Daniel




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