On Monday 08 February 2010, Guennadi Liakhovetski wrote:
> 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.
You need a support for that at the bus type/device type/device class level,
because the core doesn't execute the driver callbacks directly.
Rafael
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> ---
>
> I've posted this patch to linux-media earlier, but I'd also like to get
> comments on linux-pm, sorry to linux-media falks for a duplicate. To
> explain a bit - soc_camera.c is a management module, that binds video
> interfaces on SoCs and sensor drivers. The calls, that I am adding to
> soc_camera.c shall save and restore sensor registers before they are
> powered down and after they are powered up.
>
> diff --git a/drivers/media/video/soc_camera.c b/drivers/media/video/soc_camera.c
> index 6b3fbcc..53201f3 100644
> --- a/drivers/media/video/soc_camera.c
> +++ b/drivers/media/video/soc_camera.c
> @@ -24,6 +24,7 @@
> #include <linux/mutex.h>
> #include <linux/module.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/vmalloc.h>
>
> #include <media/soc_camera.h>
> @@ -387,6 +388,11 @@ 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,
> @@ -408,10 +414,12 @@ 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)
> @@ -436,7 +444,11 @@ 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);
> }
> @@ -1294,6 +1306,7 @@ 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)
> @@ -1310,6 +1323,9 @@ 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;
> }
>
> diff --git a/include/media/soc_camera.h b/include/media/soc_camera.h
> index dcc5b86..58b39a9 100644
> --- a/include/media/soc_camera.h
> +++ b/include/media/soc_camera.h
> @@ -282,4 +282,12 @@ static inline void soc_camera_limit_side(unsigned int *start,
> 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
> _______________________________________________
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