HSI: omap_ssi: call msg->complete() from process context

msg->complete() should always be called from process context once
irq_safe runtime pm flag is no longer set for omap-ssi.

Signed-off-by: Sebastian Reichel <[e-mail]>
Tested-by: Pavel Machek <[e-mail]>

drivers/hsi/controllers/omap_ssi.h

···
  * @txqueue: TX message queues
  * @rxqueue: RX message queues
  * @brkqueue: Queue of incoming HWBREAK requests (FRAME mode)
+ * @errqueue: Queue for failed messages
+ * @errqueue_work: Delayed Work for failed messages
  * @irq: IRQ number
  * @wake_irq: IRQ number for incoming wake line (-1 if none)
  * @wake_gpio: GPIO number for incoming wake line (-1 if none)
···
 	struct list_head	txqueue[SSI_MAX_CHANNELS];
 	struct list_head	rxqueue[SSI_MAX_CHANNELS];
 	struct list_head	brkqueue;
+	struct list_head	errqueue;
+	struct delayed_work	errqueue_work;
 	unsigned int		irq;
 	int			wake_irq;
 	struct gpio_desc	*wake_gpio;

drivers/hsi/controllers/omap_ssi_core.c

···
 		spin_lock(&omap_port->lock);
 		list_del(&msg->link); /* Dequeue msg */
 		spin_unlock(&omap_port->lock);
-		msg->complete(msg);
+
+		list_add_tail(&msg->link, &omap_port->errqueue);
+		schedule_delayed_work(&omap_port->errqueue_work, 0);
 		return;
 	}
 	spin_lock(&omap_port->lock);

drivers/hsi/controllers/omap_ssi_port.c

···
 }
 #endif
 
+static void ssi_process_errqueue(struct work_struct *work)
+{
+	struct omap_ssi_port *omap_port;
+	struct list_head *head, *tmp;
+	struct hsi_msg *msg;
+
+	omap_port = container_of(work, struct omap_ssi_port, errqueue_work.work);
+
+	list_for_each_safe(head, tmp, &omap_port->errqueue) {
+		msg = list_entry(head, struct hsi_msg, link);
+		msg->complete(msg);
+		list_del(head);
+	}
+}
+
 static int ssi_claim_lch(struct hsi_msg *msg)
 {
 
···
 	omap_port->pdev = &pd->dev;
 	omap_port->port_id = port_id;
 
+	INIT_DEFERRABLE_WORK(&omap_port->errqueue_work, ssi_process_errqueue);
 	INIT_WORK(&omap_port->work, start_tx_work);
 
 	/* initialize HSI port */
···
 #ifdef CONFIG_DEBUG_FS
 	ssi_debug_remove_port(port);
 #endif
+
+	cancel_delayed_work_sync(&omap_port->errqueue_work);
 
 	hsi_port_unregister_clients(port);