Em Fri, 6 Oct 2017 13:22:29 +0300 Sakari Ailus <sakari.ailus@xxxxxx> escreveu: > Hi Mauro, > > Thanks for continuing the work on this! > > On Wed, Sep 27, 2017 at 07:23:43PM -0300, Mauro Carvalho Chehab wrote: > > Add a glossary of terms for V4L2, as several concepts are complex > > enough to cause misunderstandings. > > > > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> > > --- > > Documentation/media/uapi/v4l/glossary.rst | 136 ++++++++++++++++++++++++++++++ > > Documentation/media/uapi/v4l/v4l2.rst | 1 + > > 2 files changed, 137 insertions(+) > > create mode 100644 Documentation/media/uapi/v4l/glossary.rst > > > > diff --git a/Documentation/media/uapi/v4l/glossary.rst b/Documentation/media/uapi/v4l/glossary.rst > > new file mode 100644 > > index 000000000000..b6767da1a46e > > --- /dev/null > > +++ b/Documentation/media/uapi/v4l/glossary.rst > > @@ -0,0 +1,136 @@ > > +======== > > +Glossary > > +======== > > + > > +.. note:: > > + > > + This goal of section is to standardize the terms used within the V4L2 > > + documentation. It is written incrementally as they are standardized in > > + the V4L2 documentation. So, it is a Work In Progress. > > + > > +.. Please keep the glossary entries in alphabetical order > > + > > +.. glossary:: > > + > > + Bridge driver > > + The same as V4L2 main driver. > > Not all V4L2 main drivers can be bridge drivers. Mem-to-mem devices, for > instance. How about: > > A driver for a device receiving image data from another device (or > transmitting it to a sub-device) controlled by a sub-device driver. Bridge > drivers typically act as V4L2 main drivers. > > > + > > + Device Node > > + A character device node in the file system used to control and do > > + input/output data transfers from/to a Kernel driver. > > + > > + Digital Signal Processor - DSP > > + A specialized microprocessor, with its architecture optimized for > > + the operational needs of digital signal processing. > > + > > + Driver > > + The part of the Linux Kernel that implements support > > + for a hardware component. > > + > > + Field-programmable Gate Array - FPGA > > + A field-programmable gate array (FPGA) is an integrated circuit > > + designed to be configured by a customer or a designer after > > + manufacturing. > > + > > + See https://en.wikipedia.org/wiki/Field-programmable_gate_array. > > + > > + Hardware component > > + A subset of the media hardware. For example an I²C or SPI device, > > + or an IP block inside an SoC or FPGA. > > + > > + Image Signal Processor - ISP > > + A specialised processor that implements a set of algorithms for > > + processing image data. ISPs may implement algorithms for lens > > + shading correction, demosaic, scaling and pixel format conversion > > + as well as produce statistics for the use of the control > > + algorithms (e.g. automatic exposure, white balance and focus). > > And perhaps add: > > ISP drivers often contain a receiver for image data from external source > such as a sensor and act as V4L2 main driver. OK. > > > + > > + Inter-Integrated Circuit - I²C > > + A multi-master, multi-slave, packet switched, single-ended, > > + serial computer bus used to control V4L2 sub-devices. > > + > > + See http://www.nxp.com/docs/en/user-guide/UM10204.pdf. > > + > > + Integrated circuit - IC > > + A set of electronic circuits on one small flat piece of > > + semiconductor material, normally silicon. > > + > > + Also known as chip. > > + > > + Intellectual property core - IP core > > + In electronic design a semiconductor intellectual property core, > > + is a reusable unit of logic, cell, or integrated circuit layout > > + design that is the intellectual property of one party. > > + IP cores may be licensed to another party or can be owned > > + and used by a single party alone. > > + > > + See https://en.wikipedia.org/wiki/Semiconductor_intellectual_property_core). > > + > > + IP block > > + The same as IP core. > > + > > + MC-centric > > + V4L2 hardware that requires a Media controller. > > + > > + See :ref:`v4l2_hardware_control`. > > + > > + Media Controller > > + An API designed to expose and control devices and sub-devices > > + relationships to applications. > > + > > + See :ref:`media_controller`. > > + > > + Media hardware > > + A group of hardware components that together make a larger > > + user-facing functional media hardware. For instance the SoC ISP IP > > + cores and external camera sensors together make a > > + camera media hardware. > > + > > + Media hardware control > > + Type of control for a media hardware supported by V4L2 drivers. > > + > > + See :ref:`v4l2_hardware_control`. > > + > > + Microprocessor > > + An electronic circuitry that carries out the instructions > > + of a computer program by performing the basic arithmetic, logical, > > + control and input/output (I/O) operations specified by the > > + instructions on a single integrated circuit. > > + > > + SMBus > > + A subset of I²C, with defines a stricter usage of the bus. > > + > > + Serial Peripheral Interface Bus - SPI > > + Synchronous serial communication interface specification used for > > + short distance communication, primarily in embedded systems. > > + > > + System on a Chip - SoC > > + An integrated circuit that integrates all components of a computer > > + or other electronic systems. > > + > > + V4L2 device node > > + A device node that is associated to a V4L2 main driver, > > + as specified in :ref:`v4l2_device_naming`. > > + > > + V4L2 hardware > > + A hardware used to on a media device supported by the V4L2 > > + subsystem. > > I'm not sure what this means. Nor I think the proposed term is good for the > reasons elaborated earlier. "Media hardware" above has similar issues. > > What we would need a name for is a device that consists of other devices > that are not usable individually, but instead as an ensemble. > > I think "aggregate device", for instance, would be good as it catches the > essence of the nature of the system. We'd have "Media aggregate device" and > "V4L2 aggregate device". > > An alternative would be simply to leave this out for now, but then we'll > have issues elsewhere. I'm certainly open for better options if someone can > come up with a better name. I liked Hans proposal for it: V4L2 hardware Hardware that is controlled by a V4L2 main driver or a V4L2 sub-device driver. V4L2 hardware is a subset of the Media hardware. Often the two are the same, but Media hardware can also contain other non-V4L2 hardware such as DVB hardware. Perhaps we could change it a little bit to contain the word "ensemble", e. g.: V4L2 hardware Ensembles the hardware that is controlled by a V4L2 main driver and by the associated V4L2 sub-device drivers. V4L2 hardware is a subset of the Media hardware. Often the two are the same, but Media hardware can also contain other non-V4L2 hardware such as DVB hardware. > > > + > > + V4L2 main driver > > + The V4L2 device driver that implements the main logic to talk with > > + the V4L2 hardware. > > + > > + Also known as bridge driver. > > + > > + See :ref:`v4l2_hardware_control`. > > + > > + V4L2 sub-device > > + Part of the media hardware that is implemented via a > > + V4L2 sub-device driver. > > + > > + See :ref:`subdev`. > > + > > + Vdevnode-centric > > I think this looks quite awkward. How about "Video device node centric" or > "Video node centric"? I don't think it'd be too long. I'll add the full name here and for MC-centric. > > > + V4L2 hardware that it is controlled via V4L2 device nodes. > > + > > + See :ref:`v4l2_hardware_control`. > > diff --git a/Documentation/media/uapi/v4l/v4l2.rst b/Documentation/media/uapi/v4l/v4l2.rst > > index 2128717299b3..698c060939f0 100644 > > --- a/Documentation/media/uapi/v4l/v4l2.rst > > +++ b/Documentation/media/uapi/v4l/v4l2.rst > > @@ -32,6 +32,7 @@ This part describes the Video for Linux API version 2 (V4L2 API) specification. > > videodev > > capture-example > > v4l2grab-example > > + glossary > > biblio > > > > > I'm enclosing the diff, against v7, that should hopefully cover all the points that both you and Hans mentioned. Thanks, Mauro diff --git a/Documentation/media/uapi/v4l/glossary.rst b/Documentation/media/uapi/v4l/glossary.rst index b6767da1a46e..08980e9cb98e 100644 --- a/Documentation/media/uapi/v4l/glossary.rst +++ b/Documentation/media/uapi/v4l/glossary.rst @@ -13,15 +13,20 @@ Glossary .. glossary:: Bridge driver - The same as V4L2 main driver. + A driver that provides a bridge between the CPU's bus to the + data and control buses of a media hardware. Often, the + bridge driver is the same as V4L2 main driver. + + Chip: + See: Integrated circuit. Device Node - A character device node in the file system used to control and do - input/output data transfers from/to a Kernel driver. + A character device node in the file system used to control and/or + do input/output data transfers from/to a Kernel driver. Digital Signal Processor - DSP A specialized microprocessor, with its architecture optimized for - the operational needs of digital signal processing. + the operational requirements of digital signal processing. Driver The part of the Linux Kernel that implements support @@ -45,9 +50,13 @@ Glossary as well as produce statistics for the use of the control algorithms (e.g. automatic exposure, white balance and focus). + ISP drivers often contain a receiver for image data from external + sources such as sensors and act as V4L2 main driver. + Inter-Integrated Circuit - I²C A multi-master, multi-slave, packet switched, single-ended, - serial computer bus used to control V4L2 sub-devices. + serial computer bus. Most V4L2 sub-devices are controlled + via this bus. See http://www.nxp.com/docs/en/user-guide/UM10204.pdf. @@ -67,23 +76,23 @@ Glossary See https://en.wikipedia.org/wiki/Semiconductor_intellectual_property_core). IP block - The same as IP core. - - MC-centric - V4L2 hardware that requires a Media controller. - - See :ref:`v4l2_hardware_control`. + See: IP core. Media Controller - An API designed to expose and control devices and sub-devices - relationships to applications. + An API designed to expose and control the relationships of the Media + Harware to applications. See :ref:`media_controller`. + Media Controller centric - MC-centric + V4L2 hardware that requires a Media controller. + + See :ref:`v4l2_hardware_control`. + Media hardware - A group of hardware components that together make a larger - user-facing functional media hardware. For instance the SoC ISP IP - cores and external camera sensors together make a + A group of hardware components that together form the + functional media hardware. For instance the SoC ISP IP + cores and external camera sensors together form the camera media hardware. Media hardware control @@ -113,8 +122,10 @@ Glossary as specified in :ref:`v4l2_device_naming`. V4L2 hardware - A hardware used to on a media device supported by the V4L2 - subsystem. + Hardware that is controlled by a V4L2 main driver or a V4L2 + sub-device driver. V4L2 hardware is a subset of the + Media hardware. Often the two are the same, but Media hardware + can also contain other non-V4L2 hardware such as DVB hardware. V4L2 main driver The V4L2 device driver that implements the main logic to talk with @@ -125,12 +136,15 @@ Glossary See :ref:`v4l2_hardware_control`. V4L2 sub-device - Part of the media hardware that is implemented via a - V4L2 sub-device driver. + See: :ref:`V4L2 sub-device driver` + + V4L2 sub-device driver + A driver for a media component whose bus(es) connects it + to the hardware controlled via the V4L2 main driver. See :ref:`subdev`. - Vdevnode-centric - V4L2 hardware that it is controlled via V4L2 device nodes. + Video device node centric - Vdevnode-centric + V4L2 hardware that is controlled via V4L2 device nodes. See :ref:`v4l2_hardware_control`.
