spi: spidev: use spi_sync instead of spi_async

This has the benefit that the "optimization" of the framework in regards
to spi_sync will also benefit spidev users directly and allow running
spi transfers without a necessary context-switch to message-pump.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spidev.c

@@ -95,37 +95,25 @@ MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
 
 /*-------------------------------------------------------------------------*/
 
-/*
- * We can't use the standard synchronous wrappers for file I/O; we
- * need to protect against async removal of the underlying spi_device.
- */
-static void spidev_complete(void *arg)
-{
-	complete(arg);
-}
-
 static ssize_t
 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 {
 	DECLARE_COMPLETION_ONSTACK(done);
 	int status;
-
-	message->complete = spidev_complete;
-	message->context = &done;
+	struct spi_device *spi;
 
 	spin_lock_irq(&spidev->spi_lock);
-	if (spidev->spi == NULL)
+	spi = spidev->spi;
+	spin_unlock_irq(&spidev->spi_lock);
+
+	if (spi == NULL)
 		status = -ESHUTDOWN;
 	else
-		status = spi_async(spidev->spi, message);
-	spin_unlock_irq(&spidev->spi_lock);
+		status = spi_sync(spi, message);
+
+	if (status == 0)
+		status = message->actual_length;
 
-	if (status == 0) {
-		wait_for_completion(&done);
-		status = message->status;
-		if (status == 0)
-			status = message->actual_length;
-	}
 	return status;
 }