From 43605e293eb13c07acb546c14f407a271837af17 Mon Sep 17 00:00:00 2001
From: Alexander Usyskin <alexander.usyskin@intel.com>
Date: Wed, 19 Oct 2016 01:34:48 +0300
Subject: [PATCH] mei: txe: don't clean an unprocessed interrupt cause.

SEC registers are not accessible when the TXE device is in low power
state, hence the SEC interrupt cannot be processed if device is not
awake.

In some rare cases entrance to low power state (aliveness off) and input
ready bits can be signaled at the same time, resulting in communication
stall as input ready won't be signaled again after waking up. To resolve
this IPC_HHIER_SEC bit in HHISR_REG should not be cleaned if the
interrupt is not processed.

Cc: stable@vger.kernel.org
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/misc/mei/hw-txe.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/mei/hw-txe.c b/drivers/misc/mei/hw-txe.c
index e6e5e55a12ed..60415a2bfcbd 100644
--- a/drivers/misc/mei/hw-txe.c
+++ b/drivers/misc/mei/hw-txe.c
@@ -981,11 +981,13 @@ static bool mei_txe_check_and_ack_intrs(struct mei_device *dev, bool do_ack)
 	hisr = mei_txe_br_reg_read(hw, HISR_REG);
 
 	aliveness = mei_txe_aliveness_get(dev);
-	if (hhisr & IPC_HHIER_SEC && aliveness)
+	if (hhisr & IPC_HHIER_SEC && aliveness) {
 		ipc_isr = mei_txe_sec_reg_read_silent(hw,
 				SEC_IPC_HOST_INT_STATUS_REG);
-	else
+	} else {
 		ipc_isr = 0;
+		hhisr &= ~IPC_HHIER_SEC;
+	}
 
 	generated = generated ||
 		(hisr & HISR_INT_STS_MSK) ||
-- 
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