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Diffstat (limited to 'Documentation/media/uapi/v4l/vidioc-querycap.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/vidioc-querycap.rst | 581 |
1 files changed, 208 insertions, 373 deletions
diff --git a/Documentation/media/uapi/v4l/vidioc-querycap.rst b/Documentation/media/uapi/v4l/vidioc-querycap.rst index b10fed313f99..165d8314327e 100644 --- a/Documentation/media/uapi/v4l/vidioc-querycap.rst +++ b/Documentation/media/uapi/v4l/vidioc-querycap.rst @@ -15,7 +15,8 @@ VIDIOC_QUERYCAP - Query device capabilities Synopsis ======== -.. cpp:function:: int ioctl( int fd, int request, struct v4l2_capability *argp ) +.. c:function:: int ioctl( int fd, VIDIOC_QUERYCAP, struct v4l2_capability *argp ) + :name: VIDIOC_QUERYCAP Arguments @@ -24,9 +25,6 @@ Arguments ``fd`` File descriptor returned by :ref:`open() <func-open>`. -``request`` - VIDIOC_QUERYCAP - ``argp`` @@ -36,389 +34,226 @@ Description All V4L2 devices support the ``VIDIOC_QUERYCAP`` ioctl. It is used to identify kernel devices compatible with this specification and to obtain information about driver and hardware capabilities. The ioctl takes a -pointer to a struct :ref:`v4l2_capability <v4l2-capability>` which is +pointer to a struct :c:type:`v4l2_capability` which is filled by the driver. When the driver is not compatible with this specification the ioctl returns an ``EINVAL`` error code. -.. _v4l2-capability: +.. tabularcolumns:: |p{1.5cm}|p{2.5cm}|p{13cm}| + +.. c:type:: v4l2_capability .. flat-table:: struct v4l2_capability :header-rows: 0 :stub-columns: 0 - :widths: 1 1 2 - - - - .. row 1 - - - __u8 - - - ``driver``\ [16] - - - Name of the driver, a unique NUL-terminated ASCII string. For - example: "bttv". Driver specific applications can use this - information to verify the driver identity. It is also useful to - work around known bugs, or to identify drivers in error reports. - - Storing strings in fixed sized arrays is bad practice but - unavoidable here. Drivers and applications should take precautions - to never read or write beyond the end of the array and to make - sure the strings are properly NUL-terminated. - - - .. row 2 - - - __u8 - - - ``card``\ [32] - - - Name of the device, a NUL-terminated UTF-8 string. For example: - "Yoyodyne TV/FM". One driver may support different brands or - models of video hardware. This information is intended for users, - for example in a menu of available devices. Since multiple TV - cards of the same brand may be installed which are supported by - the same driver, this name should be combined with the character - device file name (e. g. ``/dev/video2``) or the ``bus_info`` - string to avoid ambiguities. - - - .. row 3 - - - __u8 - - - ``bus_info``\ [32] - - - Location of the device in the system, a NUL-terminated ASCII - string. For example: "PCI:0000:05:06.0". This information is - intended for users, to distinguish multiple identical devices. If - no such information is available the field must simply count the - devices controlled by the driver ("platform:vivi-000"). The - bus_info must start with "PCI:" for PCI boards, "PCIe:" for PCI - Express boards, "usb-" for USB devices, "I2C:" for i2c devices, - "ISA:" for ISA devices, "parport" for parallel port devices and - "platform:" for platform devices. - - - .. row 4 - - - __u32 - - - ``version`` - - - Version number of the driver. - - Starting with kernel 3.1, the version reported is provided by the - V4L2 subsystem following the kernel numbering scheme. However, it - may not always return the same version as the kernel if, for - example, a stable or distribution-modified kernel uses the V4L2 - stack from a newer kernel. - - The version number is formatted using the ``KERNEL_VERSION()`` - macro: - - - .. row 5 - - - :cspan:`2` - - - .. code-block:: c - - #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c)) - - __u32 version = KERNEL_VERSION(0, 8, 1); - - printf ("Version: %u.%u.%u\\n", - (version >> 16) & 0xFF, - (version >> 8) & 0xFF, - version & 0xFF); - - - .. row 6 - - - __u32 - - - ``capabilities`` - - - Available capabilities of the physical device as a whole, see - :ref:`device-capabilities`. The same physical device can export - multiple devices in /dev (e.g. /dev/videoX, /dev/vbiY and - /dev/radioZ). The ``capabilities`` field should contain a union of - all capabilities available around the several V4L2 devices - exported to userspace. For all those devices the ``capabilities`` - field returns the same set of capabilities. This allows - applications to open just one of the devices (typically the video - device) and discover whether video, vbi and/or radio are also - supported. - - - .. row 7 - - - __u32 - - - ``device_caps`` - - - Device capabilities of the opened device, see - :ref:`device-capabilities`. Should contain the available - capabilities of that specific device node. So, for example, - ``device_caps`` of a radio device will only contain radio related - capabilities and no video or vbi capabilities. This field is only - set if the ``capabilities`` field contains the - ``V4L2_CAP_DEVICE_CAPS`` capability. Only the ``capabilities`` - field can have the ``V4L2_CAP_DEVICE_CAPS`` capability, - ``device_caps`` will never set ``V4L2_CAP_DEVICE_CAPS``. - - - .. row 8 - - - __u32 - - - ``reserved``\ [3] - - - Reserved for future extensions. Drivers must set this array to - zero. - - + :widths: 3 4 20 + + * - __u8 + - ``driver``\ [16] + - Name of the driver, a unique NUL-terminated ASCII string. For + example: "bttv". Driver specific applications can use this + information to verify the driver identity. It is also useful to + work around known bugs, or to identify drivers in error reports. + + Storing strings in fixed sized arrays is bad practice but + unavoidable here. Drivers and applications should take precautions + to never read or write beyond the end of the array and to make + sure the strings are properly NUL-terminated. + * - __u8 + - ``card``\ [32] + - Name of the device, a NUL-terminated UTF-8 string. For example: + "Yoyodyne TV/FM". One driver may support different brands or + models of video hardware. This information is intended for users, + for example in a menu of available devices. Since multiple TV + cards of the same brand may be installed which are supported by + the same driver, this name should be combined with the character + device file name (e. g. ``/dev/video2``) or the ``bus_info`` + string to avoid ambiguities. + * - __u8 + - ``bus_info``\ [32] + - Location of the device in the system, a NUL-terminated ASCII + string. For example: "PCI:0000:05:06.0". This information is + intended for users, to distinguish multiple identical devices. If + no such information is available the field must simply count the + devices controlled by the driver ("platform:vivi-000"). The + bus_info must start with "PCI:" for PCI boards, "PCIe:" for PCI + Express boards, "usb-" for USB devices, "I2C:" for i2c devices, + "ISA:" for ISA devices, "parport" for parallel port devices and + "platform:" for platform devices. + * - __u32 + - ``version`` + - Version number of the driver. + + Starting with kernel 3.1, the version reported is provided by the + V4L2 subsystem following the kernel numbering scheme. However, it + may not always return the same version as the kernel if, for + example, a stable or distribution-modified kernel uses the V4L2 + stack from a newer kernel. + + The version number is formatted using the ``KERNEL_VERSION()`` + macro: + * - :cspan:`2` + + ``#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))`` + + ``__u32 version = KERNEL_VERSION(0, 8, 1);`` + + ``printf ("Version: %u.%u.%u\\n",`` + + ``(version >> 16) & 0xFF, (version >> 8) & 0xFF, version & 0xFF);`` + * - __u32 + - ``capabilities`` + - Available capabilities of the physical device as a whole, see + :ref:`device-capabilities`. The same physical device can export + multiple devices in /dev (e.g. /dev/videoX, /dev/vbiY and + /dev/radioZ). The ``capabilities`` field should contain a union of + all capabilities available around the several V4L2 devices + exported to userspace. For all those devices the ``capabilities`` + field returns the same set of capabilities. This allows + applications to open just one of the devices (typically the video + device) and discover whether video, vbi and/or radio are also + supported. + * - __u32 + - ``device_caps`` + - Device capabilities of the opened device, see + :ref:`device-capabilities`. Should contain the available + capabilities of that specific device node. So, for example, + ``device_caps`` of a radio device will only contain radio related + capabilities and no video or vbi capabilities. This field is only + set if the ``capabilities`` field contains the + ``V4L2_CAP_DEVICE_CAPS`` capability. Only the ``capabilities`` + field can have the ``V4L2_CAP_DEVICE_CAPS`` capability, + ``device_caps`` will never set ``V4L2_CAP_DEVICE_CAPS``. + * - __u32 + - ``reserved``\ [3] + - Reserved for future extensions. Drivers must set this array to + zero. + + + +.. tabularcolumns:: |p{6cm}|p{2.2cm}|p{8.8cm}| .. _device-capabilities: +.. cssclass:: longtable + .. flat-table:: Device Capabilities Flags :header-rows: 0 :stub-columns: 0 :widths: 3 1 4 - - - .. row 1 - - - ``V4L2_CAP_VIDEO_CAPTURE`` - - - 0x00000001 - - - The device supports the single-planar API through the - :ref:`Video Capture <capture>` interface. - - - .. row 2 - - - ``V4L2_CAP_VIDEO_CAPTURE_MPLANE`` - - - 0x00001000 - - - The device supports the :ref:`multi-planar API <planar-apis>` - through the :ref:`Video Capture <capture>` interface. - - - .. row 3 - - - ``V4L2_CAP_VIDEO_OUTPUT`` - - - 0x00000002 - - - The device supports the single-planar API through the - :ref:`Video Output <output>` interface. - - - .. row 4 - - - ``V4L2_CAP_VIDEO_OUTPUT_MPLANE`` - - - 0x00002000 - - - The device supports the :ref:`multi-planar API <planar-apis>` - through the :ref:`Video Output <output>` interface. - - - .. row 5 - - - ``V4L2_CAP_VIDEO_M2M`` - - - 0x00004000 - - - The device supports the single-planar API through the Video - Memory-To-Memory interface. - - - .. row 6 - - - ``V4L2_CAP_VIDEO_M2M_MPLANE`` - - - 0x00008000 - - - The device supports the :ref:`multi-planar API <planar-apis>` - through the Video Memory-To-Memory interface. - - - .. row 7 - - - ``V4L2_CAP_VIDEO_OVERLAY`` - - - 0x00000004 - - - The device supports the :ref:`Video Overlay <overlay>` - interface. A video overlay device typically stores captured images - directly in the video memory of a graphics card, with hardware - clipping and scaling. - - - .. row 8 - - - ``V4L2_CAP_VBI_CAPTURE`` - - - 0x00000010 - - - The device supports the :ref:`Raw VBI Capture <raw-vbi>` - interface, providing Teletext and Closed Caption data. - - - .. row 9 - - - ``V4L2_CAP_VBI_OUTPUT`` - - - 0x00000020 - - - The device supports the :ref:`Raw VBI Output <raw-vbi>` - interface. - - - .. row 10 - - - ``V4L2_CAP_SLICED_VBI_CAPTURE`` - - - 0x00000040 - - - The device supports the :ref:`Sliced VBI Capture <sliced>` - interface. - - - .. row 11 - - - ``V4L2_CAP_SLICED_VBI_OUTPUT`` - - - 0x00000080 - - - The device supports the :ref:`Sliced VBI Output <sliced>` - interface. - - - .. row 12 - - - ``V4L2_CAP_RDS_CAPTURE`` - - - 0x00000100 - - - The device supports the :ref:`RDS <rds>` capture interface. - - - .. row 13 - - - ``V4L2_CAP_VIDEO_OUTPUT_OVERLAY`` - - - 0x00000200 - - - The device supports the :ref:`Video Output Overlay <osd>` (OSD) - interface. Unlike the *Video Overlay* interface, this is a - secondary function of video output devices and overlays an image - onto an outgoing video signal. When the driver sets this flag, it - must clear the ``V4L2_CAP_VIDEO_OVERLAY`` flag and vice - versa. [#f1]_ - - - .. row 14 - - - ``V4L2_CAP_HW_FREQ_SEEK`` - - - 0x00000400 - - - The device supports the - :ref:`VIDIOC_S_HW_FREQ_SEEK` ioctl - for hardware frequency seeking. - - - .. row 15 - - - ``V4L2_CAP_RDS_OUTPUT`` - - - 0x00000800 - - - The device supports the :ref:`RDS <rds>` output interface. - - - .. row 16 - - - ``V4L2_CAP_TUNER`` - - - 0x00010000 - - - The device has some sort of tuner to receive RF-modulated video - signals. For more information about tuner programming see - :ref:`tuner`. - - - .. row 17 - - - ``V4L2_CAP_AUDIO`` - - - 0x00020000 - - - The device has audio inputs or outputs. It may or may not support - audio recording or playback, in PCM or compressed formats. PCM - audio support must be implemented as ALSA or OSS interface. For - more information on audio inputs and outputs see :ref:`audio`. - - - .. row 18 - - - ``V4L2_CAP_RADIO`` - - - 0x00040000 - - - This is a radio receiver. - - - .. row 19 - - - ``V4L2_CAP_MODULATOR`` - - - 0x00080000 - - - The device has some sort of modulator to emit RF-modulated - video/audio signals. For more information about modulator - programming see :ref:`tuner`. - - - .. row 20 - - - ``V4L2_CAP_SDR_CAPTURE`` - - - 0x00100000 - - - The device supports the :ref:`SDR Capture <sdr>` interface. - - - .. row 21 - - - ``V4L2_CAP_EXT_PIX_FORMAT`` - - - 0x00200000 - - - The device supports the struct - :ref:`v4l2_pix_format <v4l2-pix-format>` extended fields. - - - .. row 22 - - - ``V4L2_CAP_SDR_OUTPUT`` - - - 0x00400000 - - - The device supports the :ref:`SDR Output <sdr>` interface. - - - .. row 23 - - - ``V4L2_CAP_READWRITE`` - - - 0x01000000 - - - The device supports the :ref:`read() <rw>` and/or - :ref:`write() <rw>` I/O methods. - - - .. row 24 - - - ``V4L2_CAP_ASYNCIO`` - - - 0x02000000 - - - The device supports the :ref:`asynchronous <async>` I/O methods. - - - .. row 25 - - - ``V4L2_CAP_STREAMING`` - - - 0x04000000 - - - The device supports the :ref:`streaming <mmap>` I/O method. - - - .. row 26 - - - ``V4L2_CAP_DEVICE_CAPS`` - - - 0x80000000 - - - The driver fills the ``device_caps`` field. This capability can - only appear in the ``capabilities`` field and never in the - ``device_caps`` field. + * - ``V4L2_CAP_VIDEO_CAPTURE`` + - 0x00000001 + - The device supports the single-planar API through the + :ref:`Video Capture <capture>` interface. + * - ``V4L2_CAP_VIDEO_CAPTURE_MPLANE`` + - 0x00001000 + - The device supports the :ref:`multi-planar API <planar-apis>` + through the :ref:`Video Capture <capture>` interface. + * - ``V4L2_CAP_VIDEO_OUTPUT`` + - 0x00000002 + - The device supports the single-planar API through the + :ref:`Video Output <output>` interface. + * - ``V4L2_CAP_VIDEO_OUTPUT_MPLANE`` + - 0x00002000 + - The device supports the :ref:`multi-planar API <planar-apis>` + through the :ref:`Video Output <output>` interface. + * - ``V4L2_CAP_VIDEO_M2M`` + - 0x00004000 + - The device supports the single-planar API through the Video + Memory-To-Memory interface. + * - ``V4L2_CAP_VIDEO_M2M_MPLANE`` + - 0x00008000 + - The device supports the :ref:`multi-planar API <planar-apis>` + through the Video Memory-To-Memory interface. + * - ``V4L2_CAP_VIDEO_OVERLAY`` + - 0x00000004 + - The device supports the :ref:`Video Overlay <overlay>` + interface. A video overlay device typically stores captured images + directly in the video memory of a graphics card, with hardware + clipping and scaling. + * - ``V4L2_CAP_VBI_CAPTURE`` + - 0x00000010 + - The device supports the :ref:`Raw VBI Capture <raw-vbi>` + interface, providing Teletext and Closed Caption data. + * - ``V4L2_CAP_VBI_OUTPUT`` + - 0x00000020 + - The device supports the :ref:`Raw VBI Output <raw-vbi>` + interface. + * - ``V4L2_CAP_SLICED_VBI_CAPTURE`` + - 0x00000040 + - The device supports the :ref:`Sliced VBI Capture <sliced>` + interface. + * - ``V4L2_CAP_SLICED_VBI_OUTPUT`` + - 0x00000080 + - The device supports the :ref:`Sliced VBI Output <sliced>` + interface. + * - ``V4L2_CAP_RDS_CAPTURE`` + - 0x00000100 + - The device supports the :ref:`RDS <rds>` capture interface. + * - ``V4L2_CAP_VIDEO_OUTPUT_OVERLAY`` + - 0x00000200 + - The device supports the :ref:`Video Output Overlay <osd>` (OSD) + interface. Unlike the *Video Overlay* interface, this is a + secondary function of video output devices and overlays an image + onto an outgoing video signal. When the driver sets this flag, it + must clear the ``V4L2_CAP_VIDEO_OVERLAY`` flag and vice + versa. [#f1]_ + * - ``V4L2_CAP_HW_FREQ_SEEK`` + - 0x00000400 + - The device supports the + :ref:`VIDIOC_S_HW_FREQ_SEEK` ioctl + for hardware frequency seeking. + * - ``V4L2_CAP_RDS_OUTPUT`` + - 0x00000800 + - The device supports the :ref:`RDS <rds>` output interface. + * - ``V4L2_CAP_TUNER`` + - 0x00010000 + - The device has some sort of tuner to receive RF-modulated video + signals. For more information about tuner programming see + :ref:`tuner`. + * - ``V4L2_CAP_AUDIO`` + - 0x00020000 + - The device has audio inputs or outputs. It may or may not support + audio recording or playback, in PCM or compressed formats. PCM + audio support must be implemented as ALSA or OSS interface. For + more information on audio inputs and outputs see :ref:`audio`. + * - ``V4L2_CAP_RADIO`` + - 0x00040000 + - This is a radio receiver. + * - ``V4L2_CAP_MODULATOR`` + - 0x00080000 + - The device has some sort of modulator to emit RF-modulated + video/audio signals. For more information about modulator + programming see :ref:`tuner`. + * - ``V4L2_CAP_SDR_CAPTURE`` + - 0x00100000 + - The device supports the :ref:`SDR Capture <sdr>` interface. + * - ``V4L2_CAP_EXT_PIX_FORMAT`` + - 0x00200000 + - The device supports the struct + :c:type:`v4l2_pix_format` extended fields. + * - ``V4L2_CAP_SDR_OUTPUT`` + - 0x00400000 + - The device supports the :ref:`SDR Output <sdr>` interface. + * - ``V4L2_CAP_READWRITE`` + - 0x01000000 + - The device supports the :ref:`read() <rw>` and/or + :ref:`write() <rw>` I/O methods. + * - ``V4L2_CAP_ASYNCIO`` + - 0x02000000 + - The device supports the :ref:`asynchronous <async>` I/O methods. + * - ``V4L2_CAP_STREAMING`` + - 0x04000000 + - The device supports the :ref:`streaming <mmap>` I/O method. + * - ``V4L2_CAP_TOUCH`` + - 0x10000000 + - This is a touch device. + * - ``V4L2_CAP_DEVICE_CAPS`` + - 0x80000000 + - The driver fills the ``device_caps`` field. This capability can + only appear in the ``capabilities`` field and never in the + ``device_caps`` field. Return Value @@ -429,6 +264,6 @@ appropriately. The generic error codes are described at the :ref:`Generic Error Codes <gen-errors>` chapter. .. [#f1] - The struct :ref:`v4l2_framebuffer <v4l2-framebuffer>` lacks an - enum :ref:`v4l2_buf_type <v4l2-buf-type>` field, therefore the + The struct :c:type:`v4l2_framebuffer` lacks an + enum :c:type:`v4l2_buf_type` field, therefore the type of overlay is implied by the driver capabilities. |