From ca93c45755da98302c93abdd788fc09113baf9e0 Mon Sep 17 00:00:00 2001
From: Logan Gunthorpe <logang@deltatee.com>
Date: Wed, 9 Jan 2019 12:22:29 -0700
Subject: [PATCH] NTB: ntb_pingpong: Choose doorbells based on port number
Git-commit: ca93c45755da98302c93abdd788fc09113baf9e0
Patch-mainline: v5.8-rc1
References: git-fixes

This commit fixes pingpong support for existing drivers that do not
implement ntb_default_port_number() and ntb_default_peer_port_number().
This is required for hardware (like the crosslink topology of
switchtec) which cannot assign reasonable port numbers to each port due
to its perfect symmetry.

Instead of picking the doorbell to use based on the the index of the
peer, we use the peer's port number. This is a bit clearer and easier
to understand.

Fixes: c7aeb0afdcc2 ("NTB: ntb_pp: Add full multi-port NTB API support")
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Allen Hubbe <allenbh@gmail.com>
Tested-by: Alexander Fomichev <fomichev.ru@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/ntb/test/ntb_pingpong.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/ntb/test/ntb_pingpong.c b/drivers/ntb/test/ntb_pingpong.c
index 04dd46647db3..2164e8492772 100644
--- a/drivers/ntb/test/ntb_pingpong.c
+++ b/drivers/ntb/test/ntb_pingpong.c
@@ -121,15 +121,14 @@ static int pp_find_next_peer(struct pp_ctx *pp)
 	link = ntb_link_is_up(pp->ntb, NULL, NULL);
 
 	/* Find next available peer */
-	if (link & pp->nmask) {
+	if (link & pp->nmask)
 		pidx = __ffs64(link & pp->nmask);
-		out_db = BIT_ULL(pidx + 1);
-	} else if (link & pp->pmask) {
+	else if (link & pp->pmask)
 		pidx = __ffs64(link & pp->pmask);
-		out_db = BIT_ULL(pidx);
-	} else {
+	else
 		return -ENODEV;
-	}
+
+	out_db = BIT_ULL(ntb_peer_port_number(pp->ntb, pidx));
 
 	spin_lock(&pp->lock);
 	pp->out_pidx = pidx;
@@ -303,7 +302,7 @@ static void pp_init_flds(struct pp_ctx *pp)
 			break;
 	}
 
-	pp->in_db = BIT_ULL(pidx);
+	pp->in_db = BIT_ULL(lport);
 	pp->pmask = GENMASK_ULL(pidx, 0) >> 1;
 	pp->nmask = GENMASK_ULL(pcnt - 1, pidx);
 
@@ -432,4 +431,3 @@ static void __exit pp_exit(void)
 	debugfs_remove_recursive(pp_dbgfs_topdir);
 }
 module_exit(pp_exit);
-
-- 
2.16.4