[PATCH 2/2] drm: Add NULL check about irq functions

[Joonyoung Shim]

The struct drm_driver has some function pointers for irq. They are
gpu specific and some functions aren't essential things. This can
prevents creation of unnecessary dummy function for irq.

Signed-off-by: Joonyoung Shim <jy0922.shim at samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
---
 drivers/gpu/drm/drm_irq.c |   23 +++++++++++++++--------
 1 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 7497c89..4137af0 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -291,11 +291,14 @@ static void drm_irq_vgaarb_nokms(void *cookie, bool state)
 	if (!dev->irq_enabled)
 		return;
 
-	if (state)
-		dev->driver->irq_uninstall(dev);
-	else {
-		dev->driver->irq_preinstall(dev);
-		dev->driver->irq_postinstall(dev);
+	if (state) {
+		if (dev->driver->irq_uninstall)
+			dev->driver->irq_uninstall(dev);
+	} else {
+		if (dev->driver->irq_preinstall)
+			dev->driver->irq_preinstall(dev);
+		if (dev->driver->irq_postinstall)
+			dev->driver->irq_postinstall(dev);
 	}
 }
 
@@ -338,7 +341,8 @@ int drm_irq_install(struct drm_device *dev)
 	DRM_DEBUG("irq=%d\n", drm_dev_to_irq(dev));
 
 	/* Before installing handler */
-	dev->driver->irq_preinstall(dev);
+	if (dev->driver->irq_preinstall)
+		dev->driver->irq_preinstall(dev);
 
 	/* Install handler */
 	if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
@@ -363,7 +367,9 @@ int drm_irq_install(struct drm_device *dev)
 		vga_client_register(dev->pdev, (void *)dev, drm_irq_vgaarb_nokms, NULL);
 
 	/* After installing handler */
-	ret = dev->driver->irq_postinstall(dev);
+	if (dev->driver->irq_postinstall)
+		ret = dev->driver->irq_postinstall(dev);
+
 	if (ret < 0) {
 		mutex_lock(&dev->struct_mutex);
 		dev->irq_enabled = 0;
@@ -414,7 +420,8 @@ int drm_irq_uninstall(struct drm_device *dev)
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		vga_client_register(dev->pdev, NULL, NULL, NULL);
 
-	dev->driver->irq_uninstall(dev);
+	if (dev->driver->irq_uninstall)
+		dev->driver->irq_uninstall(dev);
 
 	free_irq(drm_dev_to_irq(dev), dev);
 
-- 
1.7.1