1 files changed, 58 insertions, 8 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0bc752d..e1bf257 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -882,6 +882,9 @@ EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
  * needs processing and if so call out to the driver to initialize hardware
  * and transfer each message.
  *
+ * Note that it is called both from the kthread itself and also from
+ * inside spi_sync(); the queue extraction handling at the top of the
+ * function should deal with this safely.
  */
 static void spi_pump_messages(struct kthread_work *work)
 {
@@ -900,6 +903,13 @@ static void spi_pump_messages(struct kthread_work *work)
 		return;
 	}
 
+	/* If another context is idling the device then defer */
+	if (master->idling) {
+		queue_kthread_work(&master->kworker, &master->pump_messages);
+		spin_unlock_irqrestore(&master->queue_lock, flags);
+		return;
+	}
+
 	/* Check if the queue is idle */
 	if (list_empty(&master->queue) || !master->running) {
 		if (!master->busy) {
@@ -907,7 +917,9 @@ static void spi_pump_messages(struct kthread_work *work)
 			return;
 		}
 		master->busy = false;
+		master->idling = true;
 		spin_unlock_irqrestore(&master->queue_lock, flags);
+
 		kfree(master->dummy_rx);
 		master->dummy_rx = NULL;
 		kfree(master->dummy_tx);
@@ -921,6 +933,10 @@ static void spi_pump_messages(struct kthread_work *work)
 			pm_runtime_put_autosuspend(master->dev.parent);
 		}
 		trace_spi_master_idle(master);
+
+		spin_lock_irqsave(&master->queue_lock, flags);
+		master->idling = false;
+		spin_unlock_irqrestore(&master->queue_lock, flags);
 		return;
 	}
 
@@ -1161,12 +1177,9 @@ static int spi_destroy_queue(struct spi_master *master)
 	return 0;
 }
 
-/**
- * spi_queued_transfer - transfer function for queued transfers
- * @spi: spi device which is requesting transfer
- * @msg: spi message which is to handled is queued to driver queue
- */
-static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
+static int __spi_queued_transfer(struct spi_device *spi,
+				 struct spi_message *msg,
+				 bool need_pump)
 {
 	struct spi_master *master = spi->master;
 	unsigned long flags;
@@ -1181,13 +1194,23 @@ static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
 	msg->status = -EINPROGRESS;
 
 	list_add_tail(&msg->queue, &master->queue);
-	if (!master->busy)
+	if (!master->busy && need_pump)
 		queue_kthread_work(&master->kworker, &master->pump_messages);
 
 	spin_unlock_irqrestore(&master->queue_lock, flags);
 	return 0;
 }
 
+/**
+ * spi_queued_transfer - transfer function for queued transfers
+ * @spi: spi device which is requesting transfer
+ * @msg: spi message which is to handled is queued to driver queue
+ */
+static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
+{
+	return __spi_queued_transfer(spi, msg, true);
+}
+
 static int spi_master_initialize_queue(struct spi_master *master)
 {
 	int ret;
@@ -2102,19 +2125,46 @@ static int __spi_sync(struct spi_device *spi, struct spi_message *message,
 	DECLARE_COMPLETION_ONSTACK(done);
 	int status;
 	struct spi_master *master = spi->master;
+	unsigned long flags;
+
+	status = __spi_validate(spi, message);
+	if (status != 0)
+		return status;
 
 	message->complete = spi_complete;
 	message->context = &done;
+	message->spi = spi;
 
 	if (!bus_locked)
 		mutex_lock(&master->bus_lock_mutex);
 
-	status = spi_async_locked(spi, message);
+	/* If we're not using the legacy transfer method then we will
+	 * try to transfer in the calling context so special case.
+	 * This code would be less tricky if we could remove the
+	 * support for driver implemented message queues.
+	 */
+	if (master->transfer == spi_queued_transfer) {
+		spin_lock_irqsave(&master->bus_lock_spinlock, flags);
+
+		trace_spi_message_submit(message);
+
+		status = __spi_queued_transfer(spi, message, false);
+
+		spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
+	} else {
+		status = spi_async_locked(spi, message);
+	}
 
 	if (!bus_locked)
 		mutex_unlock(&master->bus_lock_mutex);
 
 	if (status == 0) {
+		/* Push out the messages in the calling context if we
+		 * can.
+		 */
+		if (master->transfer == spi_queued_transfer)
+			spi_pump_messages(&master->pump_messages);
+
 		wait_for_completion(&done);
 		status = message->status;
 	}