[PATCH AUTOSEL 5.7 352/388] NTB: perf: Fix support for hardware that doesn't have port numbers

[Sasha Levin]

From: Logan Gunthorpe <logang@xxxxxxxxxxxx>

[ Upstream commit b54369a248c2e033bfcf5d6917e08cf9d73d54a6 ]

Legacy drivers do not have port numbers (but is reliably only two ports)
and was broken by the recent commit that added mult-port support to
ntb_perf. This is especially important to support the cross link
topology which is perfectly symmetric and cannot assign unique port
numbers easily.

Hardware that returns zero for both the local port and the peer should
just always use gidx=0 for the only peer.

Fixes: 5648e56d03fa ("NTB: ntb_perf: Add full multi-port NTB API support")
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Acked-by: Allen Hubbe <allenbh@xxxxxxxxx>
Tested-by: Alexander Fomichev <fomichev.ru@xxxxxxxxx>
Signed-off-by: Jon Mason <jdmason@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/ntb/test/ntb_perf.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 21c8a3bac1e0..0b1eae07b133 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -1460,6 +1460,16 @@ static int perf_init_peers(struct perf_ctx *perf)
 	if (perf->gidx == -1)
 		perf->gidx = pidx;
 
+	/*
+	 * Hardware with only two ports may not have unique port
+	 * numbers. In this case, the gidxs should all be zero.
+	 */
+	if (perf->pcnt == 1 &&  ntb_port_number(perf->ntb) == 0 &&
+	    ntb_peer_port_number(perf->ntb, 0) == 0) {
+		perf->gidx = 0;
+		perf->peers[0].gidx = 0;
+	}
+
 	for (pidx = 0; pidx < perf->pcnt; pidx++) {
 		ret = perf_setup_peer_mw(&perf->peers[pidx]);
 		if (ret)
-- 
2.25.1