V4L/DVB: soc-camera: add runtime pm support for subdevices

To save power soc-camera powers subdevices down, when they are not in use,
if this is supported by the platform. However, the V4L standard dictates,
that video nodes shall preserve configuration between uses. This requires
runtime power management, which is implemented by this patch. It allows
subdevice drivers to specify their runtime power-management methods, by
assigning a type to the video device.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/soc_camera.c

@@ -25,6 +25,7 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
 #include <linux/vmalloc.h>
 
 #include <media/soc_camera.h>
@@ -388,6 +389,11 @@ static int soc_camera_open(struct file *file)
 			goto eiciadd;
 		}
 
+		pm_runtime_enable(&icd->vdev->dev);
+		ret = pm_runtime_resume(&icd->vdev->dev);
+		if (ret < 0 && ret != -ENOSYS)
+			goto eresume;
+
 		/*
 		 * Try to configure with default parameters. Notice: this is the
 		 * very first open, so, we cannot race against other calls,
@@ -409,10 +415,12 @@ static int soc_camera_open(struct file *file)
 	return 0;
 
 	/*
-	 * First five errors are entered with the .video_lock held
+	 * First four errors are entered with the .video_lock held
 	 * and use_count == 1
 	 */
 esfmt:
+	pm_runtime_disable(&icd->vdev->dev);
+eresume:
 	ici->ops->remove(icd);
 eiciadd:
 	if (icl->power)
@@ -437,7 +445,11 @@ static int soc_camera_close(struct file *file)
 	if (!icd->use_count) {
 		struct soc_camera_link *icl = to_soc_camera_link(icd);
 
+		pm_runtime_suspend(&icd->vdev->dev);
+		pm_runtime_disable(&icd->vdev->dev);
+
 		ici->ops->remove(icd);
+
 		if (icl->power)
 			icl->power(icd->pdev, 0);
 	}
@@ -1319,6 +1331,7 @@ static int video_dev_create(struct soc_camera_device *icd)
  */
 static int soc_camera_video_start(struct soc_camera_device *icd)
 {
+	struct device_type *type = icd->vdev->dev.type;
 	int ret;
 
 	if (!icd->dev.parent)
@@ -1335,6 +1348,9 @@ static int soc_camera_video_start(struct soc_camera_device *icd)
 		return ret;
 	}
 
+	/* Restore device type, possibly set by the subdevice driver */
+	icd->vdev->dev.type = type;
+
 	return 0;
 }
 

include/media/soc_camera.h

@@ -284,4 +284,12 @@ static inline void soc_camera_limit_side(int *start, int *length,
 extern unsigned long soc_camera_apply_sensor_flags(struct soc_camera_link *icl,
 						   unsigned long flags);
 
+/* This is only temporary here - until v4l2-subdev begins to link to video_device */
+#include <linux/i2c.h>
+static inline struct video_device *soc_camera_i2c_to_vdev(struct i2c_client *client)
+{
+	struct soc_camera_device *icd = client->dev.platform_data;
+	return icd->vdev;
+}
+
 #endif