spi: omap2-mcspi: add runtime PM to set_cs()

Since commit ddcad7e906 omap2_mcspi_set_cs() is called without
runtime power management requested.  This patch fixes the problem by
requesting runtime power management in omap2_mcspi_set_cs().

Reported-By: Pali Rohár <pali.rohar@gmail.com>
Fixes: ddcad7e906 (spi: omap2-mcspi: Fix native cs with new set_cs)
Tested-By: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-omap2-mcspi.c

@@ -245,6 +245,7 @@ static void omap2_mcspi_set_enable(const struct spi_device *spi, int enable)
 
 static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
 {
+	struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
 	u32 l;
 
 	/* The controller handles the inverted chip selects
@@ -255,6 +256,12 @@ static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
 		enable = !enable;
 
 	if (spi->controller_state) {
+		int err = pm_runtime_get_sync(mcspi->dev);
+		if (err < 0) {
+			dev_err(mcspi->dev, "failed to get sync: %d\n", err);
+			return;
+		}
+
 		l = mcspi_cached_chconf0(spi);
 
 		if (enable)
@@ -263,6 +270,9 @@ static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
 			l |= OMAP2_MCSPI_CHCONF_FORCE;
 
 		mcspi_write_chconf0(spi, l);
+
+		pm_runtime_mark_last_busy(mcspi->dev);
+		pm_runtime_put_autosuspend(mcspi->dev);
 	}
 }