[PATCH 4.14 125/193] mailbox: bcm-flexrm-mailbox: Fix FlexRM ring flush sequence

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Anup Patel <anup.patel@xxxxxxxxxxxx>

commit a371c10ea4b38a5f120e86d906d404d50a0f4660 upstream.

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@xxxxxxxxxxxx>
Reviewed-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
Signed-off-by: Jassi Brar <jaswinder.singh@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/mailbox/bcm-flexrm-mailbox.c
+++ b/drivers/mailbox/bcm-flexrm-mailbox.c
@@ -1365,8 +1365,8 @@ static void flexrm_shutdown(struct mbox_
 	/* 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_
 		    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++) {