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-rw-r--r--linux/Documentation/video4linux/v4l2-framework.txt58
-rw-r--r--linux/drivers/media/video/v4l2-device.c37
-rw-r--r--linux/include/media/v4l2-device.h31
3 files changed, 72 insertions, 54 deletions
diff --git a/linux/Documentation/video4linux/v4l2-framework.txt b/linux/Documentation/video4linux/v4l2-framework.txt
index a6005257a..e1620e2a3 100644
--- a/linux/Documentation/video4linux/v4l2-framework.txt
+++ b/linux/Documentation/video4linux/v4l2-framework.txt
@@ -84,12 +84,14 @@ You must register the device instance:
v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
Registration will initialize the v4l2_device struct and link dev->driver_data
-to v4l2_dev. Registration will also set v4l2_dev->name to a value derived from
-dev (driver name followed by the bus_id, to be precise). You may change the
-name after registration if you want.
+to v4l2_dev. If v4l2_dev->name is empty then it will be set to a value derived
+from dev (driver name followed by the bus_id, to be precise). If you set it
+up before calling v4l2_device_register then it will be untouched. If dev is
+NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register.
The first 'dev' argument is normally the struct device pointer of a pci_dev,
-usb_device or platform_device.
+usb_device or platform_device. It is rare for dev to be NULL, but it happens
+with ISA devices, for example.
You unregister with:
@@ -531,11 +533,11 @@ struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
video buffer helper functions
-----------------------------
-The v4l2 core API provides a standard method for dealing with video
-buffers. Those methods allow a driver to implement read(), mmap() and
+The v4l2 core API provides a standard method for dealing with video
+buffers. Those methods allow a driver to implement read(), mmap() and
overlay() on a consistent way.
-There are currently methods for using video buffers on devices that
+There are currently methods for using video buffers on devices that
supports DMA with scatter/gather method (videobuf-dma-sg), DMA with
linear access (videobuf-dma-contig), and vmalloced buffers, mostly
used on USB drivers (videobuf-vmalloc).
@@ -544,50 +546,50 @@ Any driver using videobuf should provide operations (callbacks) for
four handlers:
ops->buf_setup - calculates the size of the video buffers and avoid they
- to waste more than some maximum limit of RAM;
+ to waste more than some maximum limit of RAM;
ops->buf_prepare - fills the video buffer structs and calls
videobuf_iolock() to alloc and prepare mmaped memory;
ops->buf_queue - advices the driver that another buffer were
- requested (by read() or by QBUF);
+ requested (by read() or by QBUF);
ops->buf_release - frees any buffer that were allocated.
In order to use it, the driver need to have a code (generally called at
interrupt context) that will properly handle the buffer request lists,
announcing that a new buffer were filled.
-The irq handling code should handle the videobuf task lists, in order
-to advice videobuf that a new frame were filled, in order to honor to a
+The irq handling code should handle the videobuf task lists, in order
+to advice videobuf that a new frame were filled, in order to honor to a
request. The code is generally like this one:
- if (list_empty(&dma_q->active))
+ if (list_empty(&dma_q->active))
return;
- buf = list_entry(dma_q->active.next, struct vbuffer, vb.queue);
+ buf = list_entry(dma_q->active.next, struct vbuffer, vb.queue);
- if (!waitqueue_active(&buf->vb.done))
+ if (!waitqueue_active(&buf->vb.done))
return;
/* Some logic to handle the buf may be needed here */
- list_del(&buf->vb.queue);
- do_gettimeofday(&buf->vb.ts);
- wake_up(&buf->vb.done);
+ list_del(&buf->vb.queue);
+ do_gettimeofday(&buf->vb.ts);
+ wake_up(&buf->vb.done);
-Those are the videobuffer functions used on drivers, implemented on
+Those are the videobuffer functions used on drivers, implemented on
videobuf-core:
- Videobuf init functions
videobuf_queue_sg_init()
- Initializes the videobuf infrastructure. This function should be
- called before any other videobuf function on drivers that uses DMA
+ Initializes the videobuf infrastructure. This function should be
+ called before any other videobuf function on drivers that uses DMA
Scatter/Gather buffers.
videobuf_queue_dma_contig_init
- Initializes the videobuf infrastructure. This function should be
- called before any other videobuf function on drivers that need DMA
+ Initializes the videobuf infrastructure. This function should be
+ called before any other videobuf function on drivers that need DMA
contiguous buffers.
videobuf_queue_vmalloc_init()
- Initializes the videobuf infrastructure. This function should be
+ Initializes the videobuf infrastructure. This function should be
called before any other videobuf function on USB (and other drivers)
that need a vmalloced type of videobuf.
@@ -607,12 +609,12 @@ videobuf-core:
Stops video handling, ends mmap and frees mmap and other buffers.
- V4L2 api functions. Those functions correspond to VIDIOC_foo ioctls:
- videobuf_reqbufs(), videobuf_querybuf(), videobuf_qbuf(),
+ videobuf_reqbufs(), videobuf_querybuf(), videobuf_qbuf(),
videobuf_dqbuf(), videobuf_streamon(), videobuf_streamoff().
- V4L1 api function (corresponds to VIDIOCMBUF ioctl):
videobuf_cgmbuf()
- This function is used to provide backward compatibility with V4L1
+ This function is used to provide backward compatibility with V4L1
API.
- Some help functions for read()/poll() operations:
@@ -623,7 +625,7 @@ videobuf-core:
videobuf_poll_stream()
polling help function
-The better way to understand it is to take a look at vivi driver. One
-of the main reasons for vivi is to be a videobuf usage example. the
-vivi_thread_tick() does the task that the IRQ callback would do on PCI
+The better way to understand it is to take a look at vivi driver. One
+of the main reasons for vivi is to be a videobuf usage example. the
+vivi_thread_tick() does the task that the IRQ callback would do on PCI
drivers (or the irq callback on USB).
diff --git a/linux/drivers/media/video/v4l2-device.c b/linux/drivers/media/video/v4l2-device.c
index e84925976..cb8234437 100644
--- a/linux/drivers/media/video/v4l2-device.c
+++ b/linux/drivers/media/video/v4l2-device.c
@@ -27,15 +27,24 @@
int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
{
- if (dev == NULL || v4l2_dev == NULL)
+ if (v4l2_dev == NULL)
return -EINVAL;
- /* Warn if we apparently re-register a device */
- WARN_ON(dev_get_drvdata(dev) != NULL);
+
INIT_LIST_HEAD(&v4l2_dev->subdevs);
spin_lock_init(&v4l2_dev->lock);
v4l2_dev->dev = dev;
- snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
+ if (dev == NULL) {
+ /* If dev == NULL, then name must be filled in by the caller */
+ WARN_ON(!v4l2_dev->name[0]);
+ return 0;
+ }
+
+ /* Set name to driver name + device name if it is empty. */
+ if (!v4l2_dev->name[0])
+ snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
dev->driver->name, dev_name(dev));
+ if (dev_get_drvdata(dev))
+ v4l2_warn(v4l2_dev, "Non-NULL drvdata on register\n");
dev_set_drvdata(dev, v4l2_dev);
return 0;
}
@@ -45,10 +54,11 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
{
struct v4l2_subdev *sd, *next;
- if (v4l2_dev == NULL || v4l2_dev->dev == NULL)
+ if (v4l2_dev == NULL)
return;
- dev_set_drvdata(v4l2_dev->dev, NULL);
- /* unregister subdevs */
+ if (v4l2_dev->dev)
+ dev_set_drvdata(v4l2_dev->dev, NULL);
+ /* Unregister subdevs */
list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list)
v4l2_device_unregister_subdev(sd);
@@ -56,19 +66,20 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister);
-int v4l2_device_register_subdev(struct v4l2_device *dev, struct v4l2_subdev *sd)
+int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
+ struct v4l2_subdev *sd)
{
/* Check for valid input */
- if (dev == NULL || sd == NULL || !sd->name[0])
+ if (v4l2_dev == NULL || sd == NULL || !sd->name[0])
return -EINVAL;
/* Warn if we apparently re-register a subdev */
WARN_ON(sd->dev != NULL);
if (!try_module_get(sd->owner))
return -ENODEV;
- sd->dev = dev;
- spin_lock(&dev->lock);
- list_add_tail(&sd->list, &dev->subdevs);
- spin_unlock(&dev->lock);
+ sd->dev = v4l2_dev;
+ spin_lock(&v4l2_dev->lock);
+ list_add_tail(&sd->list, &v4l2_dev->subdevs);
+ spin_unlock(&v4l2_dev->lock);
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
diff --git a/linux/include/media/v4l2-device.h b/linux/include/media/v4l2-device.h
index 55e41afd9..5d7146dc2 100644
--- a/linux/include/media/v4l2-device.h
+++ b/linux/include/media/v4l2-device.h
@@ -33,7 +33,9 @@
#define V4L2_DEVICE_NAME_SIZE (BUS_ID_SIZE + 16)
struct v4l2_device {
- /* dev->driver_data points to this struct */
+ /* dev->driver_data points to this struct.
+ Note: dev might be NULL if there is no parent device
+ as is the case with e.g. ISA devices. */
struct device *dev;
/* used to keep track of the registered subdevs */
struct list_head subdevs;
@@ -44,7 +46,9 @@ struct v4l2_device {
char name[V4L2_DEVICE_NAME_SIZE];
};
-/* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev */
+/* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev.
+ dev may be NULL in rare cases (ISA devices). In that case you
+ must fill in the v4l2_dev->name field before calling this function. */
int __must_check v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
/* Set v4l2_dev->dev->driver_data to NULL and unregister all sub-devices */
void v4l2_device_unregister(struct v4l2_device *v4l2_dev);
@@ -52,23 +56,24 @@ void v4l2_device_unregister(struct v4l2_device *v4l2_dev);
/* Register a subdev with a v4l2 device. While registered the subdev module
is marked as in-use. An error is returned if the module is no longer
loaded when you attempt to register it. */
-int __must_check v4l2_device_register_subdev(struct v4l2_device *dev, struct v4l2_subdev *sd);
+int __must_check v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
+ struct v4l2_subdev *sd);
/* Unregister a subdev with a v4l2 device. Can also be called if the subdev
wasn't registered. In that case it will do nothing. */
void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
/* Iterate over all subdevs. */
-#define v4l2_device_for_each_subdev(sd, dev) \
- list_for_each_entry(sd, &(dev)->subdevs, list)
+#define v4l2_device_for_each_subdev(sd, v4l2_dev) \
+ list_for_each_entry(sd, &(v4l2_dev)->subdevs, list)
/* Call the specified callback for all subdevs matching the condition.
Ignore any errors. Note that you cannot add or delete a subdev
while walking the subdevs list. */
-#define __v4l2_device_call_subdevs(dev, cond, o, f, args...) \
+#define __v4l2_device_call_subdevs(v4l2_dev, cond, o, f, args...) \
do { \
struct v4l2_subdev *sd; \
\
- list_for_each_entry(sd, &(dev)->subdevs, list) \
+ list_for_each_entry(sd, &(v4l2_dev)->subdevs, list) \
if ((cond) && sd->ops->o && sd->ops->o->f) \
sd->ops->o->f(sd , ##args); \
} while (0)
@@ -77,12 +82,12 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
If the callback returns an error other than 0 or -ENOIOCTLCMD, then
return with that error code. Note that you cannot add or delete a
subdev while walking the subdevs list. */
-#define __v4l2_device_call_subdevs_until_err(dev, cond, o, f, args...) \
+#define __v4l2_device_call_subdevs_until_err(v4l2_dev, cond, o, f, args...) \
({ \
struct v4l2_subdev *sd; \
long err = 0; \
\
- list_for_each_entry(sd, &(dev)->subdevs, list) { \
+ list_for_each_entry(sd, &(v4l2_dev)->subdevs, list) { \
if ((cond) && sd->ops->o && sd->ops->o->f) \
err = sd->ops->o->f(sd , ##args); \
if (err && err != -ENOIOCTLCMD) \
@@ -94,16 +99,16 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
/* Call the specified callback for all subdevs matching grp_id (if 0, then
match them all). Ignore any errors. Note that you cannot add or delete
a subdev while walking the subdevs list. */
-#define v4l2_device_call_all(dev, grpid, o, f, args...) \
- __v4l2_device_call_subdevs(dev, \
+#define v4l2_device_call_all(v4l2_dev, grpid, o, f, args...) \
+ __v4l2_device_call_subdevs(v4l2_dev, \
!(grpid) || sd->grp_id == (grpid), o, f , ##args)
/* Call the specified callback for all subdevs matching grp_id (if 0, then
match them all). If the callback returns an error other than 0 or
-ENOIOCTLCMD, then return with that error code. Note that you cannot
add or delete a subdev while walking the subdevs list. */
-#define v4l2_device_call_until_err(dev, grpid, o, f, args...) \
- __v4l2_device_call_subdevs_until_err(dev, \
+#define v4l2_device_call_until_err(v4l2_dev, grpid, o, f, args...) \
+ __v4l2_device_call_subdevs_until_err(v4l2_dev, \
!(grpid) || sd->grp_id == (grpid), o, f , ##args)
#endif
generated by cgit v1.2.3 (git 2.25.1) at 2025-01-05 04:25:35 +0000