mei: me: wait for power gating exit confirmation

Fix the hbm power gating state machine so it will wait till it receives
confirmation interrupt for the PG_ISOLATION_EXIT message.

In process of the suspend flow the devices first have to exit from the
power gating state (runtime pm resume).
If we do not handle the confirmation interrupt after sending
PG_ISOLATION_EXIT message, we may receive it already after the suspend
flow has changed the device state and interrupt will be interpreted as a
spurious event, consequently link reset will be invoked which will
prevent the device from completing the suspend flow

kernel: [6603] mei_reset:136: mei_me 0000:00:16.0: powering down: end of reset
kernel: [476] mei_me_irq_thread_handler:643: mei_me 0000:00:16.0: function called after ISR to handle the interrupt processing.
kernel: mei_me 0000:00:16.0: FW not ready: resetting

Cc: <stable@vger.kernel.org> #3.18+
Cc: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=86241
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=770397
Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
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>

1 files changed, 55 insertions, 4 deletions

diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
index 6fb75e62a764..43d7101ff993 100644
--- a/drivers/misc/mei/hw-me.c
+++ b/drivers/misc/mei/hw-me.c
@@ -663,11 +663,27 @@ int mei_me_pg_exit_sync(struct mei_device *dev)
 	mutex_lock(&dev->device_lock);
 
 reply:
-	if (dev->pg_event == MEI_PG_EVENT_RECEIVED)
-		ret = mei_hbm_pg(dev, MEI_PG_ISOLATION_EXIT_RES_CMD);
+	if (dev->pg_event != MEI_PG_EVENT_RECEIVED) {
+		ret = -ETIME;
+		goto out;
+	}
+
+	dev->pg_event = MEI_PG_EVENT_INTR_WAIT;
+	ret = mei_hbm_pg(dev, MEI_PG_ISOLATION_EXIT_RES_CMD);
+	if (ret)
+		return ret;
+
+	mutex_unlock(&dev->device_lock);
+	wait_event_timeout(dev->wait_pg,
+		dev->pg_event == MEI_PG_EVENT_INTR_RECEIVED, timeout);
+	mutex_lock(&dev->device_lock);
+
+	if (dev->pg_event == MEI_PG_EVENT_INTR_RECEIVED)
+		ret = 0;
 	else
 		ret = -ETIME;
 
+out:
 	dev->pg_event = MEI_PG_EVENT_IDLE;
 	hw->pg_state = MEI_PG_OFF;
 
@@ -675,6 +691,19 @@ reply:
 }
 
 /**
+ * mei_me_pg_in_transition - is device now in pg transition
+ *
+ * @dev: the device structure
+ *
+ * Return: true if in pg transition, false otherwise
+ */
+static bool mei_me_pg_in_transition(struct mei_device *dev)
+{
+	return dev->pg_event >= MEI_PG_EVENT_WAIT &&
+	       dev->pg_event <= MEI_PG_EVENT_INTR_WAIT;
+}
+
+/**
  * mei_me_pg_is_enabled - detect if PG is supported by HW
  *
  * @dev: the device structure
@@ -705,6 +734,24 @@ notsupported:
 }
 
 /**
+ * mei_me_pg_intr - perform pg processing in interrupt thread handler
+ *
+ * @dev: the device structure
+ */
+static void mei_me_pg_intr(struct mei_device *dev)
+{
+	struct mei_me_hw *hw = to_me_hw(dev);
+
+	if (dev->pg_event != MEI_PG_EVENT_INTR_WAIT)
+		return;
+
+	dev->pg_event = MEI_PG_EVENT_INTR_RECEIVED;
+	hw->pg_state = MEI_PG_OFF;
+	if (waitqueue_active(&dev->wait_pg))
+		wake_up(&dev->wait_pg);
+}
+
+/**
  * mei_me_irq_quick_handler - The ISR of the MEI device
  *
  * @irq: The irq number
@@ -761,6 +808,8 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
 		goto end;
 	}
 
+	mei_me_pg_intr(dev);
+
 	/*  check if we need to start the dev */
 	if (!mei_host_is_ready(dev)) {
 		if (mei_hw_is_ready(dev)) {
@@ -797,9 +846,10 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
 	/*
 	 * During PG handshake only allowed write is the replay to the
 	 * PG exit message, so block calling write function
-	 * if the pg state is not idle
+	 * if the pg event is in PG handshake
 	 */
-	if (dev->pg_event == MEI_PG_EVENT_IDLE) {
+	if (dev->pg_event != MEI_PG_EVENT_WAIT &&
+	    dev->pg_event != MEI_PG_EVENT_RECEIVED) {
 		rets = mei_irq_write_handler(dev, &complete_list);
 		dev->hbuf_is_ready = mei_hbuf_is_ready(dev);
 	}
@@ -824,6 +874,7 @@ static const struct mei_hw_ops mei_me_hw_ops = {
 	.hw_config = mei_me_hw_config,
 	.hw_start = mei_me_hw_start,
 
+	.pg_in_transition = mei_me_pg_in_transition,
 	.pg_is_enabled = mei_me_pg_is_enabled,
 
 	.intr_clear = mei_me_intr_clear,