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thunderbolt: Fail the failed bandwidth request properly

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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: Mika Westerberg <mika.westerberg@linux.intel.com>
This commit is contained in:
Mika Westerberg 2024-01-09 17:53:53 +02:00
parent 2ec67a48cf
commit 37f49727cc
1 changed files with 18 additions and 5 deletions
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23
drivers/thunderbolt/tb.c
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@ -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;
}