[PATCH 3.12 054/133] mei: use hbm idle state to prevent spurious resets

[Greg Kroah-Hartman]

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

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

From: Tomas Winkler <tomas.winkler@xxxxxxxxx>

commit 66ae460b13c31a176b41550259683c841a62af3e upstream.

When reset is caused by hbm protocol mismatch or timeout
we might end up in an endless reset loop and hbm protocol
will never sync

Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/misc/mei/hbm.c       |   19 +++++++++++++++++++
 drivers/misc/mei/hbm.h       |    1 +
 drivers/misc/mei/init.c      |   12 ++++++++----
 drivers/misc/mei/interrupt.c |   25 +++++++++++++++----------
 4 files changed, 43 insertions(+), 14 deletions(-)

--- a/drivers/misc/mei/hbm.c
+++ b/drivers/misc/mei/hbm.c
@@ -128,6 +128,17 @@ static bool is_treat_specially_client(st
 	return false;
 }
 
+/**
+ * mei_hbm_idle - set hbm to idle state
+ *
+ * @dev: the device structure
+ */
+void mei_hbm_idle(struct mei_device *dev)
+{
+	dev->init_clients_timer = 0;
+	dev->hbm_state = MEI_HBM_IDLE;
+}
+
 int mei_hbm_start_wait(struct mei_device *dev)
 {
 	int ret;
@@ -577,6 +588,14 @@ void mei_hbm_dispatch(struct mei_device
 	mei_read_slots(dev, dev->rd_msg_buf, hdr->length);
 	mei_msg = (struct mei_bus_message *)dev->rd_msg_buf;
 
+	/* ignore spurious message and prevent reset nesting
+	 * hbm is put to idle during system reset
+	 */
+	if (dev->hbm_state == MEI_HBM_IDLE) {
+		dev_dbg(&dev->pdev->dev, "hbm: state is idle ignore spurious messages\n");
+		return 0;
+	}
+
 	switch (mei_msg->hbm_cmd) {
 	case HOST_START_RES_CMD:
 		version_res = (struct hbm_host_version_response *)mei_msg;
--- a/drivers/misc/mei/hbm.h
+++ b/drivers/misc/mei/hbm.h
@@ -49,6 +49,7 @@ static inline void mei_hbm_hdr(struct me
 	hdr->reserved = 0;
 }
 
+void mei_hbm_idle(struct mei_device *dev);
 int mei_hbm_start_req(struct mei_device *dev);
 int mei_hbm_start_wait(struct mei_device *dev);
 int mei_hbm_cl_flow_control_req(struct mei_device *dev, struct mei_cl *cl);
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -139,14 +139,19 @@ void mei_reset(struct mei_device *dev, i
 			dev->dev_state != MEI_DEV_POWER_DOWN &&
 			dev->dev_state != MEI_DEV_POWER_UP);
 
+	/* we're already in reset, cancel the init timer
+	 * if the reset was called due the hbm protocol error
+	 * we need to call it before hw start
+	 * so the hbm watchdog won't kick in
+	 */
+	mei_hbm_idle(dev);
+
 	ret = mei_hw_reset(dev, interrupts_enabled);
 	if (ret) {
 		dev_err(&dev->pdev->dev, "hw reset failed disabling the device\n");
 		interrupts_enabled = false;
-		dev->dev_state = MEI_DEV_DISABLED;
 	}
 
-	dev->hbm_state = MEI_HBM_IDLE;
 
 	if (dev->dev_state != MEI_DEV_INITIALIZING &&
 	    dev->dev_state != MEI_DEV_POWER_UP) {
@@ -175,8 +180,6 @@ void mei_reset(struct mei_device *dev, i
 		memset(&dev->wr_ext_msg, 0, sizeof(dev->wr_ext_msg));
 	}
 
-	/* we're already in reset, cancel the init timer */
-	dev->init_clients_timer = 0;
 
 	dev->me_clients_num = 0;
 	dev->rd_msg_hdr = 0;
@@ -188,6 +191,7 @@ void mei_reset(struct mei_device *dev, i
 
 	if (!interrupts_enabled) {
 		dev_dbg(&dev->pdev->dev, "intr not enabled end of reset\n");
+		dev->dev_state = MEI_DEV_DISABLED;
 		return;
 	}
 
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -536,7 +536,6 @@ EXPORT_SYMBOL_GPL(mei_irq_write_handler)
  *
  * @work: pointer to the work_struct structure
  *
- * NOTE: This function is called by timer interrupt work
  */
 void mei_timer(struct work_struct *work)
 {
@@ -551,18 +550,24 @@ void mei_timer(struct work_struct *work)
 
 
 	mutex_lock(&dev->device_lock);
-	if (dev->dev_state != MEI_DEV_ENABLED) {
-		if (dev->dev_state == MEI_DEV_INIT_CLIENTS) {
-			if (dev->init_clients_timer) {
-				if (--dev->init_clients_timer == 0) {
-					dev_err(&dev->pdev->dev, "reset: init clients timeout hbm_state = %d.\n",
-						dev->hbm_state);
-					mei_reset(dev, 1);
-				}
+
+	/* Catch interrupt stalls during HBM init handshake */
+	if (dev->dev_state == MEI_DEV_INIT_CLIENTS &&
+	    dev->hbm_state != MEI_HBM_IDLE) {
+
+		if (dev->init_clients_timer) {
+			if (--dev->init_clients_timer == 0) {
+				dev_err(&dev->pdev->dev, "timer: init clients timeout hbm_state = %d.\n",
+					dev->hbm_state);
+				mei_reset(dev, 1);
+				goto out;
 			}
 		}
-		goto out;
 	}
+
+	if (dev->dev_state != MEI_DEV_ENABLED)
+		goto out;
+
 	/*** connect/disconnect timeouts ***/
 	list_for_each_entry_safe(cl_pos, cl_next, &dev->file_list, link) {
 		if (cl_pos->timer_count) {


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