linux-kernel - [PATCH 3/4] NTB: ntb_perf: Clear stale values in doorbell and command SPAD register

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Date:   Fri, 15 Feb 2019 09:21:19 +0000
From:   "Mehta, Sanju" <Sanju.Mehta@....com>
To:     "S-k, Shyam-sundar" <Shyam-sundar.S-k@....com>,
        "jdmason@...zu.us" <jdmason@...zu.us>,
        "dave.jiang@...el.com" <dave.jiang@...el.com>,
        "allenbh@...il.com" <allenbh@...il.com>
CC:     "linux-ntb@...glegroups.com" <linux-ntb@...glegroups.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Mehta, Sanju" <Sanju.Mehta@....com>
Subject: [PATCH 3/4] NTB: ntb_perf: Clear stale values in doorbell and command
 SPAD register

From: Sanjay R Mehta <sanju.mehta@....com>

when ntb_perf is unloaded, the command scratchpad register still
retains the last initialized value of PERF_CMD_INVAL. When ntb_perf
is re-loaded and reads peer command scratchpad register and it mis
interprets the peer state as initialized.

To avoid this, clearing the local side command scratchpad register
in perf_disable_service

Signed-off-by: Sanjay R Mehta <sanju.mehta@....com>
---
 drivers/ntb/test/ntb_perf.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 4a3fba4..c7d1a48 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -754,6 +754,14 @@ static void perf_disable_service(struct perf_ctx *perf)
 	for (pidx = 0; pidx < perf->pcnt; pidx++)
 		flush_work(&perf->peers[pidx].service);
 
+	for (pidx = 0; pidx < perf->pcnt; pidx++) {
+		struct perf_peer *peer = &perf->peers[pidx];
+
+		ntb_spad_write(perf->ntb, PERF_SPAD_CMD(peer->gidx), 0);
+	}
+
+	ntb_db_clear(perf->ntb, PERF_SPAD_NOTIFY(perf->gidx));
+
 	ntb_link_disable(perf->ntb);
 }
 
-- 
2.7.4