Commit 37f49727 authored by Mika Westerberg's avatar Mika Westerberg
Browse files

thunderbolt: Fail the failed bandwidth request properly 



The USB4 spec says that if the Connection Manager writes Allocated_BW
that is smaller than Requested_BW, the DisplayPort IN adapter signals
this failure back to the DPTX (graphics driver). Implement this by
rewriting the same allocated bandwidth values back.

Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
parent 2ec67a48

drivers/thunderbolt/tb.c

+18 −5
Original line number Diff line number Diff line
@@ -2270,11 +2270,11 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up, 
	 */

	ret = tb_tunnel_maximum_bandwidth(tunnel, &max_up, &max_down);

	if (ret)

		return ret;

		goto fail;



	ret = usb4_dp_port_granularity(in);

	if (ret < 0)

		return ret;

		goto fail;

	granularity = ret;



	max_up_rounded = roundup(max_up, granularity);
@@ -2304,7 +2304,8 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up, 
			      "bandwidth request too high (%d/%d Mb/s > %d/%d Mb/s)\n",

			      requested_up_corrected, requested_down_corrected,

			      max_up_rounded, max_down_rounded);

		return -ENOBUFS;

		ret = -ENOBUFS;

		goto fail;

	}



	if ((*requested_up >= 0 && requested_up_corrected <= allocated_up) ||
@@ -2332,7 +2333,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up, 
	 */

	ret = tb_release_unused_usb3_bandwidth(tb, in, out);

	if (ret)

		return ret;

		goto fail;



	/*

	 * Then go over all tunnels that cross the same USB4 ports (they
@@ -2357,7 +2358,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up, 
					*requested_down);

		if (ret) {

			tb_configure_sym(tb, in, out, 0, 0, true);

			return ret;

			goto fail;

		}



		ret = tb_tunnel_alloc_bandwidth(tunnel, requested_up,
@@ -2372,6 +2373,18 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up, 


reclaim:

	tb_reclaim_usb3_bandwidth(tb, in, out);

fail:

	if (ret && ret != -ENODEV) {

		/*

		 * Write back the same allocated (so no change), this

		 * makes the DPTX request fail on graphics side.

		 */

		tb_tunnel_dbg(tunnel,

			      "failing the request by rewriting allocated %d/%d Mb/s\n",

			      allocated_up, allocated_down);

		tb_tunnel_alloc_bandwidth(tunnel, &allocated_up, &allocated_down);

	}



	return ret;

}