mailbox: bcm-flexrm-mailbox: Fix FlexRM ring flush sequence

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>

diff --git a/drivers/mailbox/bcm-flexrm-mailbox.c b/drivers/mailbox/bcm-flexrm-mailbox.c
index ae6146311934dcc5235341bc966229cfc8cd9cf6..f052a3eb2098392465591d05ea426e92dd006406 100644 (file)
--- 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++) {