| Message ID | a73d058a4c04bbcf9716fd41fce844675629f8d9.1403652043.git.shuah.kh@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Shuah, On 06/25/2014 01:57 AM, Shuah Khan wrote: > Add a new field tuner_tkn to struct video_device. Drivers can > create tuner token using devm_token_create() and initialize > the tuner_tkn when frontend is registered with the dvb-core. > This change enables drivers to provide a token devres for tuner > access control. > > Change v4l2-core to lock tuner token for exclusive access to > tuner function for analog TV function use. When Tuner token is > present, v4l2_open() calls devm_token_lock() to lock the token. > If token is busy, -EBUSY is returned to the user-space. > > Tuner token is unlocked in error paths in v4l2_open(). This token > is held as long as the v4l2 device is open and unlocked from > v4l2_release(). > > Signed-off-by: Shuah Khan <shuah.kh@samsung.com> > --- > drivers/media/v4l2-core/v4l2-dev.c | 23 ++++++++++++++++++++++- > include/media/v4l2-dev.h | 1 + > 2 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c > index 634d863..8dff809 100644 > --- a/drivers/media/v4l2-core/v4l2-dev.c > +++ b/drivers/media/v4l2-core/v4l2-dev.c > @@ -26,6 +26,7 @@ > #include <linux/kmod.h> > #include <linux/slab.h> > #include <asm/uaccess.h> > +#include <linux/token_devres.h> > > #include <media/v4l2-common.h> > #include <media/v4l2-device.h> > @@ -445,6 +446,17 @@ static int v4l2_open(struct inode *inode, struct file *filp) > mutex_unlock(&videodev_lock); > return -ENODEV; > } > + /* check if tuner is busy first */ > + if (vdev->tuner_tkn && vdev->dev_parent) { > + ret = devm_token_lock(vdev->dev_parent, vdev->tuner_tkn); > + if (ret) { > + mutex_unlock(&videodev_lock); > + dev_info(vdev->dev_parent, "v4l2: Tuner is busy\n"); > + return ret; > + } If I understand this correctly, then this will make it impossible to open the same video node twice since devm_token_lock will return EBUSY the second time. Ditto for DVB as far as I could tell. That is certainly not what you want, at least not for V4L. In V4L2 the rules for tuner ownership are complicated, especially if the tuner has a radio mode as well, see this presentation (the last two slides): http://linuxtv.org/downloads/presentations/media_ws_2012_EU/ambiguities2.odp Regards, Hans > + dev_info(vdev->dev_parent, "v4l2: Tuner is locked\n"); > + } > + > /* and increase the device refcount */ > video_get(vdev); > mutex_unlock(&videodev_lock); > @@ -459,8 +471,13 @@ static int v4l2_open(struct inode *inode, struct file *filp) > printk(KERN_DEBUG "%s: open (%d)\n", > video_device_node_name(vdev), ret); > /* decrease the refcount in case of an error */ > - if (ret) > + if (ret) { > video_put(vdev); > + if (vdev->tuner_tkn && vdev->dev_parent) { > + devm_token_unlock(vdev->dev_parent, vdev->tuner_tkn); > + dev_info(vdev->dev_parent, "v4l2: Tuner is unlocked\n"); > + } > + } > return ret; > } > > @@ -479,6 +496,10 @@ static int v4l2_release(struct inode *inode, struct file *filp) > /* decrease the refcount unconditionally since the release() > return value is ignored. */ > video_put(vdev); > + if (vdev->tuner_tkn && vdev->dev_parent) { > + devm_token_unlock(vdev->dev_parent, vdev->tuner_tkn); > + dev_info(vdev->dev_parent, "v4l2: Tuner is unlocked\n"); > + } > return ret; > } > > diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h > index eec6e46..1676349 100644 > --- a/include/media/v4l2-dev.h > +++ b/include/media/v4l2-dev.h > @@ -141,6 +141,7 @@ struct video_device > /* serialization lock */ > DECLARE_BITMAP(disable_locking, BASE_VIDIOC_PRIVATE); > struct mutex *lock; > + char *tuner_tkn; > }; > > #define media_entity_to_video_device(__e) \ > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index 634d863..8dff809 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -26,6 +26,7 @@ #include <linux/kmod.h> #include <linux/slab.h> #include <asm/uaccess.h> +#include <linux/token_devres.h> #include <media/v4l2-common.h> #include <media/v4l2-device.h> @@ -445,6 +446,17 @@ static int v4l2_open(struct inode *inode, struct file *filp) mutex_unlock(&videodev_lock); return -ENODEV; } + /* check if tuner is busy first */ + if (vdev->tuner_tkn && vdev->dev_parent) { + ret = devm_token_lock(vdev->dev_parent, vdev->tuner_tkn); + if (ret) { + mutex_unlock(&videodev_lock); + dev_info(vdev->dev_parent, "v4l2: Tuner is busy\n"); + return ret; + } + dev_info(vdev->dev_parent, "v4l2: Tuner is locked\n"); + } + /* and increase the device refcount */ video_get(vdev); mutex_unlock(&videodev_lock); @@ -459,8 +471,13 @@ static int v4l2_open(struct inode *inode, struct file *filp) printk(KERN_DEBUG "%s: open (%d)\n", video_device_node_name(vdev), ret); /* decrease the refcount in case of an error */ - if (ret) + if (ret) { video_put(vdev); + if (vdev->tuner_tkn && vdev->dev_parent) { + devm_token_unlock(vdev->dev_parent, vdev->tuner_tkn); + dev_info(vdev->dev_parent, "v4l2: Tuner is unlocked\n"); + } + } return ret; } @@ -479,6 +496,10 @@ static int v4l2_release(struct inode *inode, struct file *filp) /* decrease the refcount unconditionally since the release() return value is ignored. */ video_put(vdev); + if (vdev->tuner_tkn && vdev->dev_parent) { + devm_token_unlock(vdev->dev_parent, vdev->tuner_tkn); + dev_info(vdev->dev_parent, "v4l2: Tuner is unlocked\n"); + } return ret; } diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h index eec6e46..1676349 100644 --- a/include/media/v4l2-dev.h +++ b/include/media/v4l2-dev.h @@ -141,6 +141,7 @@ struct video_device /* serialization lock */ DECLARE_BITMAP(disable_locking, BASE_VIDIOC_PRIVATE); struct mutex *lock; + char *tuner_tkn; }; #define media_entity_to_video_device(__e) \
Add a new field tuner_tkn to struct video_device. Drivers can create tuner token using devm_token_create() and initialize the tuner_tkn when frontend is registered with the dvb-core. This change enables drivers to provide a token devres for tuner access control. Change v4l2-core to lock tuner token for exclusive access to tuner function for analog TV function use. When Tuner token is present, v4l2_open() calls devm_token_lock() to lock the token. If token is busy, -EBUSY is returned to the user-space. Tuner token is unlocked in error paths in v4l2_open(). This token is held as long as the v4l2 device is open and unlocked from v4l2_release(). Signed-off-by: Shuah Khan <shuah.kh@samsung.com> --- drivers/media/v4l2-core/v4l2-dev.c | 23 ++++++++++++++++++++++- include/media/v4l2-dev.h | 1 + 2 files changed, 23 insertions(+), 1 deletion(-)