On Tue, 13 Sep 2011, Laurent Pinchart wrote:
> Hi Guennadi,
>
> On Monday 12 September 2011 12:55:46 Guennadi Liakhovetski wrote:
> > Currently only very few drivers actually use video_device nodes, embedded
> > in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> > to save memory for the rest.
> >
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> > ---
> >
> > v3: addressed comments from Laurent Pinchart - thanks
>
> Thanks for the patch. Just one small comment below.
>
> > 1. switch to using a device-release method, instead of freeing directly in
> > v4l2_device_unregister_subdev()
> >
> > 2. switch to using drvdata instead of a wrapper struct
> >
> > drivers/media/video/v4l2-device.c | 41
> > ++++++++++++++++++++++++++++++++---- include/media/v4l2-subdev.h |
> > 4 +-
> > 2 files changed, 38 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/media/video/v4l2-device.c
> > b/drivers/media/video/v4l2-device.c index c72856c..9bf3d70 100644
> > --- a/drivers/media/video/v4l2-device.c
> > +++ b/drivers/media/video/v4l2-device.c
> > @@ -21,6 +21,7 @@
> > #include <linux/types.h>
> > #include <linux/ioctl.h>
> > #include <linux/i2c.h>
> > +#include <linux/slab.h>
> > #if defined(CONFIG_SPI)
> > #include <linux/spi/spi.h>
> > #endif
> > @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device
> > *v4l2_dev, }
> > EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> >
> > +void v4l2_device_release_subdev_node(struct video_device *vdev)
> > +{
> > + struct v4l2_subdev *sd = video_get_drvdata(vdev);
> > + sd->devnode = NULL;
> > + kfree(vdev);
> > +}
> > +
> > int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> > {
> > struct video_device *vdev;
> > @@ -204,22 +212,42 @@ int v4l2_device_register_subdev_nodes(struct
> > v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
> > continue;
> >
> > - vdev = &sd->devnode;
> > + vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> > + if (!vdev) {
> > + err = -ENOMEM;
> > + goto clean_up;
> > + }
> > +
> > + video_set_drvdata(vdev, sd);
> > strlcpy(vdev->name, sd->name, sizeof(vdev->name));
> > vdev->v4l2_dev = v4l2_dev;
> > vdev->fops = &v4l2_subdev_fops;
> > - vdev->release = video_device_release_empty;
> > + vdev->release = v4l2_device_release_subdev_node;
> > vdev->ctrl_handler = sd->ctrl_handler;
> > err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
> > sd->owner);
> > - if (err < 0)
> > - return err;
> > + if (err < 0) {
> > + kfree(vdev);
> > + goto clean_up;
> > + }
> > + get_device(&vdev->dev);
>
> Is get_device() (and the corresponding put_device() calls below) required ? I
> thought device_register() initialized the reference count to 1 (don't take my
> word for it though).
Indeed, I think, you're right. Will update.
Thanks
Guennadi
>
> > #if defined(CONFIG_MEDIA_CONTROLLER)
> > sd->entity.v4l.major = VIDEO_MAJOR;
> > sd->entity.v4l.minor = vdev->minor;
> > #endif
> > + sd->devnode = vdev;
> > }
> > return 0;
> > +
> > +clean_up:
> > + list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> > + if (!sd->devnode)
> > + break;
> > + video_unregister_device(sd->devnode);
> > + put_device(&sd->devnode->dev);
> > + }
> > +
> > + return err;
> > }
> > EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
> >
> > @@ -245,7 +273,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev
> > *sd) if (v4l2_dev->mdev)
> > media_device_unregister_entity(&sd->entity);
> > #endif
> > - video_unregister_device(&sd->devnode);
> > + if (sd->devnode) {
> > + video_unregister_device(sd->devnode);
> > + put_device(&sd->devnode->dev);
> > + }
> > module_put(sd->owner);
> > }
> > EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> > index 257da1a..5dd049a 100644
> > --- a/include/media/v4l2-subdev.h
> > +++ b/include/media/v4l2-subdev.h
> > @@ -534,13 +534,13 @@ struct v4l2_subdev {
> > void *dev_priv;
> > void *host_priv;
> > /* subdev device node */
> > - struct video_device devnode;
> > + struct video_device *devnode;
> > };
> >
> > #define media_entity_to_v4l2_subdev(ent) \
> > container_of(ent, struct v4l2_subdev, entity)
> > #define vdev_to_v4l2_subdev(vdev) \
> > - container_of(vdev, struct v4l2_subdev, devnode)
> > + video_get_drvdata(vdev)
> >
> > /*
> > * Used for storing subdev information per file handle
>
> --
> Regards,
>
> Laurent Pinchart
>
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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