mei: retry connect if interrupted by link reset

When device is in D3cold the connect message will wake device
and cause link reset.
Link reset flow cleans all queues and wakes all waiters.
Retry the connect flow if connect is failed and link reset is detected.

Signed-off-by: Alexander Usyskin <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/misc/mei/hw.h

···
 #define MKHI_RCV_TIMEOUT 500 /* receive timeout in msec */
 #define MKHI_RCV_TIMEOUT_SLOW 10000 /* receive timeout in msec, slow FW */
 
+#define MEI_LINK_RESET_WAIT_TIMEOUT_MSEC 500  /* Max wait timeout for link reset, in msec */
+
 /*
  * FW page size for DMA allocations
  */

drivers/misc/mei/init.c

···
 	init_waitqueue_head(&dev->wait_pg);
 	init_waitqueue_head(&dev->wait_hbm_start);
 	dev->dev_state = MEI_DEV_UNINITIALIZED;
+	init_waitqueue_head(&dev->wait_dev_state);
 	dev->reset_count = 0;
 
 	INIT_LIST_HEAD(&dev->write_list);
···
 		dev->timeouts.hbm = mei_secs_to_jiffies(MEI_HBM_TIMEOUT);
 		dev->timeouts.mkhi_recv = msecs_to_jiffies(MKHI_RCV_TIMEOUT);
 	}
+	dev->timeouts.link_reset_wait = msecs_to_jiffies(MEI_LINK_RESET_WAIT_TIMEOUT_MSEC);
 }
 EXPORT_SYMBOL_GPL(mei_device_init);

drivers/misc/mei/main.c

···
 	    cl->state != MEI_FILE_DISCONNECTED)
 		return  -EBUSY;
 
+retry:
 	/* find ME client we're trying to connect to */
 	me_cl = mei_me_cl_by_uuid(dev, in_client_uuid);
 	if (!me_cl) {
···
 	cl_dbg(dev, cl, "Can connect?\n");
 
 	rets = mei_cl_connect(cl, me_cl, file);
+
+	if (rets && cl->status == -EFAULT &&
+	    (dev->dev_state == MEI_DEV_RESETTING ||
+	     dev->dev_state == MEI_DEV_INIT_CLIENTS)) {
+		/* in link reset, wait for it completion */
+		mutex_unlock(&dev->device_lock);
+		rets = wait_event_interruptible_timeout(dev->wait_dev_state,
+							dev->dev_state == MEI_DEV_ENABLED,
+							dev->timeouts.link_reset_wait);
+		mutex_lock(&dev->device_lock);
+		if (rets < 0) {
+			if (signal_pending(current))
+				rets = -EINTR;
+			goto end;
+		}
+		if (dev->dev_state != MEI_DEV_ENABLED) {
+			rets = -ETIME;
+			goto end;
+		}
+		mei_me_cl_put(me_cl);
+		goto retry;
+	}
 
 end:
 	mei_me_cl_put(me_cl);
···
 		return;
 
 	dev->dev_state = state;
+
+	wake_up_interruptible_all(&dev->wait_dev_state);
 
 	if (!dev->cdev)
 		return;

drivers/misc/mei/mei_dev.h

···
 	unsigned int d0i3; /* D0i3 set/unset max response time, in jiffies */
 	unsigned long hbm; /* HBM operation timeout, in jiffies */
 	unsigned long mkhi_recv; /* receive timeout, in jiffies */
+	unsigned long link_reset_wait; /* link reset wait timeout, in jiffies */
 };
 
 /**
···
  *
  * @reset_count : number of consecutive resets
  * @dev_state   : device state
+ * @wait_dev_state: wait queue for device state change
  * @hbm_state   : state of host bus message protocol
  * @pxp_mode    : PXP device mode
  * @init_clients_timer : HBM init handshake timeout
···
 	 */
 	unsigned long reset_count;
 	enum mei_dev_state dev_state;
+	wait_queue_head_t wait_dev_state;
 	enum mei_hbm_state hbm_state;
 	enum mei_dev_pxp_mode pxp_mode;
 	u16 init_clients_timer;