On Tue, 13 Sep 2011, Laurent Pinchart wrote:
> Hi Guennadi,
>
> On Tuesday 13 September 2011 11:26:23 Guennadi Liakhovetski wrote:
> > On Tue, 13 Sep 2011, Laurent Pinchart wrote:
> > > 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.
>
> Please test it as well :-)
I'm afraid, testing it wouldn't be very easy for me: I only have one
system here, on which MC is used - the beagle-board. And it is not an easy
nor a quick exersize to bring it up and run a test on it;-) But if noone
else finds time to test it and if we're not confident enough in its
correctness, well, we'll have to wait until I find time to do that...
BTW, there's one more improvement to be made for this patch:
-void v4l2_device_release_subdev_node(struct video_device *vdev)
+static void v4l2_device_release_subdev_node(struct video_device *vdev)
My copy-paste from video_device_release_empty() was too precise:-(
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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