From a371c10ea4b38a5f120e86d906d404d50a0f4660 Mon Sep 17 00:00:00 2001
From: Anup Patel <anup.patel@broadcom.com>
Date: Tue, 3 Oct 2017 10:51:48 +0530
Subject: [PATCH] mailbox: bcm-flexrm-mailbox: Fix FlexRM ring flush sequence
Git-commit: a371c10ea4b38a5f120e86d906d404d50a0f4660
Patch-mainline: v4.15-rc1
References: bsc#1051510

As-per suggestion from FlexRM HW folks, we have to first set
FlexRM ring flush state and then clear it for FlexRM ring flush
to work properly.

Currently, the FlexRM driver has incomplete FlexRM ring flush
sequence which causes repeated insmod+rmmod of mailbox client
drivers to fail.

This patch fixes FlexRM ring flush sequence in flexrm_shutdown()
as described above.

Fixes: dbc049eee730 ("mailbox: Add driver for Broadcom FlexRM
ring manager")

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/mailbox/bcm-flexrm-mailbox.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/mailbox/bcm-flexrm-mailbox.c b/drivers/mailbox/bcm-flexrm-mailbox.c
index ae6146311934..f052a3eb2098 100644
--- a/drivers/mailbox/bcm-flexrm-mailbox.c
+++ b/drivers/mailbox/bcm-flexrm-mailbox.c
@@ -1365,8 +1365,8 @@ static void flexrm_shutdown(struct mbox_chan *chan)
 	/* Disable/inactivate ring */
 	writel_relaxed(0x0, ring->regs + RING_CONTROL);
 
-	/* Flush ring with timeout of 1s */
-	timeout = 1000;
+	/* Set ring flush state */
+	timeout = 1000; /* timeout of 1s */
 	writel_relaxed(BIT(CONTROL_FLUSH_SHIFT),
 			ring->regs + RING_CONTROL);
 	do {
@@ -1374,7 +1374,23 @@ static void flexrm_shutdown(struct mbox_chan *chan)
 		    FLUSH_DONE_MASK)
 			break;
 		mdelay(1);
-	} while (timeout--);
+	} while (--timeout);
+	if (!timeout)
+		dev_err(ring->mbox->dev,
+			"setting ring%d flush state timedout\n", ring->num);
+
+	/* Clear ring flush state */
+	timeout = 1000; /* timeout of 1s */
+	writel_relaxed(0x0, ring + RING_CONTROL);
+	do {
+		if (!(readl_relaxed(ring + RING_FLUSH_DONE) &
+		      FLUSH_DONE_MASK))
+			break;
+		mdelay(1);
+	} while (--timeout);
+	if (!timeout)
+		dev_err(ring->mbox->dev,
+			"clearing ring%d flush state timedout\n", ring->num);
 
 	/* Abort all in-flight requests */
 	for (reqid = 0; reqid < RING_MAX_REQ_COUNT; reqid++) {
-- 
2.18.0