diff options
Diffstat (limited to 'drivers/media')
| -rw-r--r-- | drivers/media/v4l2-core/v4l2-dev.c | 34 |
1 files changed, 14 insertions, 20 deletions
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index 33617c3..9aa530a 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -194,7 +194,7 @@ static void v4l2_device_release(struct device *cd) mutex_unlock(&videodev_lock); #if defined(CONFIG_MEDIA_CONTROLLER) - if (v4l2_dev && v4l2_dev->mdev && + if (v4l2_dev->mdev && vdev->vfl_type != VFL_TYPE_SUBDEV) media_device_unregister_entity(&vdev->entity); #endif @@ -207,7 +207,7 @@ static void v4l2_device_release(struct device *cd) * TODO: In the long run all drivers that use v4l2_device should use the * v4l2_device release callback. This check will then be unnecessary. */ - if (v4l2_dev && v4l2_dev->release == NULL) + if (v4l2_dev->release == NULL) v4l2_dev = NULL; /* Release video_device and perform other @@ -360,27 +360,22 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) * hack but it will have to do for those drivers that are not * yet converted to use unlocked_ioctl. * - * There are two options: if the driver implements struct - * v4l2_device, then the lock defined there is used to - * serialize the ioctls. Otherwise the v4l2 core lock defined - * below is used. This lock is really bad since it serializes - * completely independent devices. + * All drivers implement struct v4l2_device, so we use the + * lock defined there to serialize the ioctls. * - * Both variants suffer from the same problem: if the driver - * sleeps, then it blocks all ioctls since the lock is still - * held. This is very common for VIDIOC_DQBUF since that - * normally waits for a frame to arrive. As a result any other - * ioctl calls will proceed very, very slowly since each call - * will have to wait for the VIDIOC_QBUF to finish. Things that - * should take 0.01s may now take 10-20 seconds. + * However, if the driver sleeps, then it blocks all ioctls + * since the lock is still held. This is very common for + * VIDIOC_DQBUF since that normally waits for a frame to arrive. + * As a result any other ioctl calls will proceed very, very + * slowly since each call will have to wait for the VIDIOC_QBUF + * to finish. Things that should take 0.01s may now take 10-20 + * seconds. * * The workaround is to *not* take the lock for VIDIOC_DQBUF. * This actually works OK for videobuf-based drivers, since * videobuf will take its own internal lock. */ - static DEFINE_MUTEX(v4l2_ioctl_mutex); - struct mutex *m = vdev->v4l2_dev ? - &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex; + struct mutex *m = &vdev->v4l2_dev->ioctl_lock; if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m)) return -ERESTARTSYS; @@ -938,12 +933,11 @@ int __video_register_device(struct video_device *vdev, int type, int nr, name_base, nr, video_device_node_name(vdev)); /* Increase v4l2_device refcount */ - if (vdev->v4l2_dev) - v4l2_device_get(vdev->v4l2_dev); + v4l2_device_get(vdev->v4l2_dev); #if defined(CONFIG_MEDIA_CONTROLLER) /* Part 5: Register the entity. */ - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && + if (vdev->v4l2_dev->mdev && vdev->vfl_type != VFL_TYPE_SUBDEV) { vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L; vdev->entity.name = vdev->name; |
