netdev - [PATCH net 2/2] be2net: Need a delay before processing CQE after 2nd mbox register write

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Message-ID: <4b4fd4cb-9d23-4900-a20c-f2c2bef70849@CMEXHTCAS2.ad.emulex.com>
Date:	Wed, 8 Jan 2014 14:52:02 +0530
From:	Somnath Kotur <somnath.kotur@...lex.com>
To:	<netdev@...r.kernel.org>
CC:	<davem@...emloft.net>, Somnath Kotur <somnath.kotur@...lex.com>,
	Kalesh AP <kalesh.purayil@...lex.com>
Subject: [PATCH net 2/2] be2net: Need a delay before processing CQE after 2nd mbox register write

Due to Host platform synchronization issues between the mbox RDY bit polled
status and the completion of the DMA for the CQE, it is preferable that the
Host always wait for the RDY bit to transition to 1 after the 2nd mbox register
write and always follow that with a short wait for the valid bit in the CQE,
before processing the CQE.

Signed-off-by: Kalesh AP <kalesh.purayil@...lex.com>
Signed-off-by: Somnath Kotur <somnath.kotur@...lex.com>
---
 drivers/net/ethernet/emulex/benet/be_cmds.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ethernet/emulex/benet/be_cmds.c b/drivers/net/ethernet/emulex/benet/be_cmds.c
index 94c35c8..78560f2 100644
--- a/drivers/net/ethernet/emulex/benet/be_cmds.c
+++ b/drivers/net/ethernet/emulex/benet/be_cmds.c
@@ -502,6 +502,9 @@ static int be_mbox_notify_wait(struct be_adapter *adapter)
 	if (status != 0)
 		return status;
 
+	/* Need a delay before processing CQE after 2nd mbox register write */
+	udelay(1);
+
 	/* A cq entry has been made now */
 	if (be_mcc_compl_is_new(compl)) {
 		status = be_mcc_compl_process(adapter, &mbox->compl);
-- 
1.6.0.2

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