diff options
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/dma-buf.rst | 13 | ||||
| -rw-r--r-- | Documentation/driver-api/fpga/fpga-bridge.rst | 10 | ||||
| -rw-r--r-- | Documentation/driver-api/fpga/fpga-mgr.rst | 12 | ||||
| -rw-r--r-- | Documentation/driver-api/fpga/fpga-programming.rst | 8 | ||||
| -rw-r--r-- | Documentation/driver-api/fpga/fpga-region.rst | 20 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/consumer.rst | 10 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/driver.rst | 11 | ||||
| -rw-r--r-- | Documentation/driver-api/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/driver-api/lightnvm-pblk.rst | 21 | ||||
| -rw-r--r-- | Documentation/driver-api/media/camera-sensor.rst | 45 | ||||
| -rw-r--r-- | Documentation/driver-api/media/cec-core.rst | 9 | ||||
| -rw-r--r-- | Documentation/driver-api/media/csi2.rst | 94 | ||||
| -rw-r--r-- | Documentation/driver-api/media/index.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/media/tx-rx.rst | 133 | ||||
| -rw-r--r-- | Documentation/driver-api/nfc/nfc-hci.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/thermal/nouveau_thermal.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/vfio.rst | 4 |
17 files changed, 213 insertions, 184 deletions
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index 7f21425d9435..f5ac4c90b237 100644 --- a/Documentation/driver-api/dma-buf.rst +++ b/Documentation/driver-api/dma-buf.rst @@ -88,6 +88,9 @@ consider though: - The DMA buffer FD is also pollable, see `Implicit Fence Poll Support`_ below for details. +- The DMA buffer FD also supports a few dma-buf-specific ioctls, see + `DMA Buffer ioctls`_ below for details. + Basic Operation and Device DMA Access ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -106,6 +109,16 @@ Implicit Fence Poll Support .. kernel-doc:: drivers/dma-buf/dma-buf.c :doc: implicit fence polling +DMA-BUF statistics +~~~~~~~~~~~~~~~~~~ +.. kernel-doc:: drivers/dma-buf/dma-buf-sysfs-stats.c + :doc: overview + +DMA Buffer ioctls +~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/uapi/linux/dma-buf.h + Kernel Functions and Structures Reference ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/Documentation/driver-api/fpga/fpga-bridge.rst b/Documentation/driver-api/fpga/fpga-bridge.rst index 198aadafd3e7..8d650b4e2ce6 100644 --- a/Documentation/driver-api/fpga/fpga-bridge.rst +++ b/Documentation/driver-api/fpga/fpga-bridge.rst @@ -4,11 +4,11 @@ FPGA Bridge API to implement a new FPGA bridge ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -* struct fpga_bridge — The FPGA Bridge structure -* struct fpga_bridge_ops — Low level Bridge driver ops -* devm_fpga_bridge_create() — Allocate and init a bridge struct -* fpga_bridge_register() — Register a bridge -* fpga_bridge_unregister() — Unregister a bridge +* struct fpga_bridge - The FPGA Bridge structure +* struct fpga_bridge_ops - Low level Bridge driver ops +* devm_fpga_bridge_create() - Allocate and init a bridge struct +* fpga_bridge_register() - Register a bridge +* fpga_bridge_unregister() - Unregister a bridge .. kernel-doc:: include/linux/fpga/fpga-bridge.h :functions: fpga_bridge diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst index 917ee22db429..4d926b452cb3 100644 --- a/Documentation/driver-api/fpga/fpga-mgr.rst +++ b/Documentation/driver-api/fpga/fpga-mgr.rst @@ -101,12 +101,12 @@ in state. API for implementing a new FPGA Manager driver ---------------------------------------------- -* ``fpga_mgr_states`` — Values for :c:expr:`fpga_manager->state`. -* struct fpga_manager — the FPGA manager struct -* struct fpga_manager_ops — Low level FPGA manager driver ops -* devm_fpga_mgr_create() — Allocate and init a manager struct -* fpga_mgr_register() — Register an FPGA manager -* fpga_mgr_unregister() — Unregister an FPGA manager +* ``fpga_mgr_states`` - Values for :c:expr:`fpga_manager->state`. +* struct fpga_manager - the FPGA manager struct +* struct fpga_manager_ops - Low level FPGA manager driver ops +* devm_fpga_mgr_create() - Allocate and init a manager struct +* fpga_mgr_register() - Register an FPGA manager +* fpga_mgr_unregister() - Unregister an FPGA manager .. kernel-doc:: include/linux/fpga/fpga-mgr.h :functions: fpga_mgr_states diff --git a/Documentation/driver-api/fpga/fpga-programming.rst b/Documentation/driver-api/fpga/fpga-programming.rst index 002392dab04f..fb4da4240e96 100644 --- a/Documentation/driver-api/fpga/fpga-programming.rst +++ b/Documentation/driver-api/fpga/fpga-programming.rst @@ -84,10 +84,10 @@ will generate that list. Here's some sample code of what to do next:: API for programming an FPGA --------------------------- -* fpga_region_program_fpga() — Program an FPGA -* fpga_image_info() — Specifies what FPGA image to program -* fpga_image_info_alloc() — Allocate an FPGA image info struct -* fpga_image_info_free() — Free an FPGA image info struct +* fpga_region_program_fpga() - Program an FPGA +* fpga_image_info() - Specifies what FPGA image to program +* fpga_image_info_alloc() - Allocate an FPGA image info struct +* fpga_image_info_free() - Free an FPGA image info struct .. kernel-doc:: drivers/fpga/fpga-region.c :functions: fpga_region_program_fpga diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst index 363a8171ab0a..2636a27c11b2 100644 --- a/Documentation/driver-api/fpga/fpga-region.rst +++ b/Documentation/driver-api/fpga/fpga-region.rst @@ -45,19 +45,19 @@ An example of usage can be seen in the probe function of [#f2]_. API to add a new FPGA region ---------------------------- -* struct fpga_region — The FPGA region struct -* devm_fpga_region_create() — Allocate and init a region struct -* fpga_region_register() — Register an FPGA region -* fpga_region_unregister() — Unregister an FPGA region +* struct fpga_region - The FPGA region struct +* devm_fpga_region_create() - Allocate and init a region struct +* fpga_region_register() - Register an FPGA region +* fpga_region_unregister() - Unregister an FPGA region The FPGA region's probe function will need to get a reference to the FPGA Manager it will be using to do the programming. This usually would happen during the region's probe function. -* fpga_mgr_get() — Get a reference to an FPGA manager, raise ref count -* of_fpga_mgr_get() — Get a reference to an FPGA manager, raise ref count, +* fpga_mgr_get() - Get a reference to an FPGA manager, raise ref count +* of_fpga_mgr_get() - Get a reference to an FPGA manager, raise ref count, given a device node. -* fpga_mgr_put() — Put an FPGA manager +* fpga_mgr_put() - Put an FPGA manager The FPGA region will need to specify which bridges to control while programming the FPGA. The region driver can build a list of bridges during probe time @@ -66,11 +66,11 @@ the list of bridges to program just before programming (:c:expr:`fpga_region->get_bridges`). The FPGA bridge framework supplies the following APIs to handle building or tearing down that list. -* fpga_bridge_get_to_list() — Get a ref of an FPGA bridge, add it to a +* fpga_bridge_get_to_list() - Get a ref of an FPGA bridge, add it to a list -* of_fpga_bridge_get_to_list() — Get a ref of an FPGA bridge, add it to a +* of_fpga_bridge_get_to_list() - Get a ref of an FPGA bridge, add it to a list, given a device node -* fpga_bridges_put() — Given a list of bridges, put them +* fpga_bridges_put() - Given a list of bridges, put them .. kernel-doc:: include/linux/fpga/fpga-region.h :functions: fpga_region diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst index 3366a991b4aa..47869ca8ccf0 100644 --- a/Documentation/driver-api/gpio/consumer.rst +++ b/Documentation/driver-api/gpio/consumer.rst @@ -72,6 +72,10 @@ for the GPIO. Values can be: * GPIOD_OUT_HIGH_OPEN_DRAIN same as GPIOD_OUT_HIGH but also enforce the line to be electrically used with open drain. +Note that the initial value is *logical* and the physical line level depends on +whether the line is configured active high or active low (see +:ref:`active_low_semantics`). + The two last flags are used for use cases where open drain is mandatory, such as I2C: if the line is not already configured as open drain in the mappings (see board.txt), then open drain will be enforced anyway and a warning will be @@ -252,6 +256,8 @@ that can't be accessed from hardIRQ handlers, these calls act the same as the spinlock-safe calls. +.. _active_low_semantics: + The active low and open drain semantics --------------------------------------- As a consumer should not have to care about the physical line level, all of the @@ -309,9 +315,11 @@ work on the raw line value:: void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value) int gpiod_direction_output_raw(struct gpio_desc *desc, int value) -The active low state of a GPIO can also be queried using the following call:: +The active low state of a GPIO can also be queried and toggled using the +following calls:: int gpiod_is_active_low(const struct gpio_desc *desc) + void gpiod_toggle_active_low(struct gpio_desc *desc) Note that these functions should only be used with great moderation; a driver should not have to care about the physical line level or open drain semantics. diff --git a/Documentation/driver-api/gpio/driver.rst b/Documentation/driver-api/gpio/driver.rst index d6b0d779859b..bbc53920d4dd 100644 --- a/Documentation/driver-api/gpio/driver.rst +++ b/Documentation/driver-api/gpio/driver.rst @@ -547,13 +547,10 @@ To use the helpers please keep the following in mind: the irqchip can initialize. E.g. .dev and .can_sleep shall be set up properly. -- Nominally set all handlers to handle_bad_irq() in the setup call and pass - handle_bad_irq() as flow handler parameter in gpiochip_irqchip_add() if it is - expected for GPIO driver that irqchip .set_type() callback will be called - before using/enabling each GPIO IRQ. Then set the handler to - handle_level_irq() and/or handle_edge_irq() in the irqchip .set_type() - callback depending on what your controller supports and what is requested - by the consumer. +- Nominally set gpio_irq_chip.handler to handle_bad_irq. Then, if your irqchip + is cascaded, set the handler to handle_level_irq() and/or handle_edge_irq() + in the irqchip .set_type() callback depending on what your controller + supports and what is requested by the consumer. Locking IRQ usage diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index f5a3207aa7fa..c57c609ad2eb 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -85,7 +85,6 @@ available subsections can be seen below. io-mapping io_ordering generic-counter - lightnvm-pblk memory-devices/index men-chameleon-bus ntb diff --git a/Documentation/driver-api/lightnvm-pblk.rst b/Documentation/driver-api/lightnvm-pblk.rst deleted file mode 100644 index 1040ed1cec81..000000000000 --- a/Documentation/driver-api/lightnvm-pblk.rst +++ /dev/null @@ -1,21 +0,0 @@ -pblk: Physical Block Device Target -================================== - -pblk implements a fully associative, host-based FTL that exposes a traditional -block I/O interface. Its primary responsibilities are: - - - Map logical addresses onto physical addresses (4KB granularity) in a - logical-to-physical (L2P) table. - - Maintain the integrity and consistency of the L2P table as well as its - recovery from normal tear down and power outage. - - Deal with controller- and media-specific constrains. - - Handle I/O errors. - - Implement garbage collection. - - Maintain consistency across the I/O stack during synchronization points. - -For more information please refer to: - - http://lightnvm.io - -which maintains updated FAQs, manual pages, technical documentation, tools, -contacts, etc. diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst index 7160336aa475..c7d4891bd24e 100644 --- a/Documentation/driver-api/media/camera-sensor.rst +++ b/Documentation/driver-api/media/camera-sensor.rst @@ -3,10 +3,10 @@ Writing camera sensor drivers ============================= -CSI-2 ------ +CSI-2 and parallel (BT.601 and BT.656) busses +--------------------------------------------- -Please see what is written on :ref:`MIPI_CSI_2`. +Please see :ref:`transmitter-receiver`. Handling clocks --------------- @@ -26,15 +26,16 @@ user. ACPI ~~~~ -Read the "clock-frequency" _DSD property to denote the frequency. The driver can -rely on this frequency being used. +Read the ``clock-frequency`` _DSD property to denote the frequency. The driver +can rely on this frequency being used. Devicetree ~~~~~~~~~~ -The currently preferred way to achieve this is using "assigned-clock-rates" -property. See Documentation/devicetree/bindings/clock/clock-bindings.txt for -more information. The driver then gets the frequency using clk_get_rate(). +The currently preferred way to achieve this is using ``assigned-clocks``, +``assigned-clock-parents`` and ``assigned-clock-rates`` properties. See +``Documentation/devicetree/bindings/clock/clock-bindings.txt`` for more +information. The driver then gets the frequency using ``clk_get_rate()``. This approach has the drawback that there's no guarantee that the frequency hasn't been modified directly or indirectly by another driver, or supported by @@ -55,7 +56,7 @@ processing pipeline as one or more sub-devices with different cropping and scaling configurations. The output size of the device is the result of a series of cropping and scaling operations from the device's pixel array's size. -An example of such a driver is the smiapp driver (see drivers/media/i2c/smiapp). +An example of such a driver is the CCS driver (see ``drivers/media/i2c/ccs``). Register list based drivers ~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -67,7 +68,7 @@ level are independent. How a driver picks such configuration is based on the format set on a source pad at the end of the device's internal pipeline. Most sensor drivers are implemented this way, see e.g. -drivers/media/i2c/imx319.c for an example. +``drivers/media/i2c/imx319.c`` for an example. Frame interval configuration ---------------------------- @@ -94,9 +95,10 @@ large variety of devices beyond camera sensors. Devices that have no analogue crop, use the full source image size, i.e. pixel array size. Horizontal and vertical blanking are specified by ``V4L2_CID_HBLANK`` and -``V4L2_CID_VBLANK``, respectively. The unit of these controls are lines. The -pixel rate is specified by ``V4L2_CID_PIXEL_RATE`` in the same sub-device. The -unit of that control is Hz. +``V4L2_CID_VBLANK``, respectively. The unit of the ``V4L2_CID_HBLANK`` control +is pixels and the unit of the ``V4L2_CID_VBLANK`` is lines. The pixel rate in +the sensor's **pixel array** is specified by ``V4L2_CID_PIXEL_RATE`` in the same +sub-device. The unit of that control is pixels per second. Register list based drivers need to implement read-only sub-device nodes for the purpose. Devices that are not register list based need these to configure the @@ -125,14 +127,14 @@ general, the device must be powered on at least when its registers are being accessed and when it is streaming. Existing camera sensor drivers may rely on the old -:c:type:`v4l2_subdev_core_ops`->s_power() callback for bridge or ISP drivers to +struct v4l2_subdev_core_ops->s_power() callback for bridge or ISP drivers to manage their power state. This is however **deprecated**. If you feel you need to begin calling an s_power from an ISP or a bridge driver, instead please add runtime PM support to the sensor driver you are using. Likewise, new drivers should not use s_power. Please see examples in e.g. ``drivers/media/i2c/ov8856.c`` and -``drivers/media/i2c/smiapp/smiapp-core.c``. The two drivers work in both ACPI +``drivers/media/i2c/ccs/ccs-core.c``. The two drivers work in both ACPI and DT based systems. Control framework @@ -149,16 +151,3 @@ used to obtain device's power state after the power state transition: The function returns a non-zero value if it succeeded getting the power count or runtime PM was disabled, in either of which cases the driver may proceed to access the device. - -Controls --------- - -For camera sensors that are connected to a bus where transmitter and receiver -require common configuration set by drivers, such as CSI-2 or parallel (BT.601 -or BT.656) bus, the ``V4L2_CID_LINK_FREQ`` control is mandatory on transmitter -drivers. Receiver drivers can use the ``V4L2_CID_LINK_FREQ`` to query the -frequency used on the bus. - -The transmitter drivers should also implement ``V4L2_CID_PIXEL_RATE`` control in -order to tell the maximum pixel rate to the receiver. This is required on raw -camera sensors. diff --git a/Documentation/driver-api/media/cec-core.rst b/Documentation/driver-api/media/cec-core.rst index 56345eae9a26..c6194ee81c41 100644 --- a/Documentation/driver-api/media/cec-core.rst +++ b/Documentation/driver-api/media/cec-core.rst @@ -130,9 +130,12 @@ To enable/disable the hardware:: int (*adap_enable)(struct cec_adapter *adap, bool enable); This callback enables or disables the CEC hardware. Enabling the CEC hardware -means powering it up in a state where no logical addresses are claimed. This -op assumes that the physical address (adap->phys_addr) is valid when enable is -true and will not change while the CEC adapter remains enabled. The initial +means powering it up in a state where no logical addresses are claimed. The +physical address will always be valid if CEC_CAP_NEEDS_HPD is set. If that +capability is not set, then the physical address can change while the CEC +hardware is enabled. CEC drivers should not set CEC_CAP_NEEDS_HPD unless +the hardware design requires that as this will make it impossible to wake +up displays that pull the HPD low when in standby mode. The initial state of the CEC adapter after calling cec_allocate_adapter() is disabled. Note that adap_enable must return 0 if enable is false. diff --git a/Documentation/driver-api/media/csi2.rst b/Documentation/driver-api/media/csi2.rst deleted file mode 100644 index 11c52b0be8b8..000000000000 --- a/Documentation/driver-api/media/csi2.rst +++ /dev/null @@ -1,94 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 - -.. _MIPI_CSI_2: - -MIPI CSI-2 -========== - -CSI-2 is a data bus intended for transferring images from cameras to -the host SoC. It is defined by the `MIPI alliance`_. - -.. _`MIPI alliance`: http://www.mipi.org/ - -Media bus formats ------------------ - -See :ref:`v4l2-mbus-pixelcode` for details on which media bus formats should -be used for CSI-2 interfaces. - -Transmitter drivers -------------------- - -CSI-2 transmitter, such as a sensor or a TV tuner, drivers need to -provide the CSI-2 receiver with information on the CSI-2 bus -configuration. These include the V4L2_CID_LINK_FREQ and -V4L2_CID_PIXEL_RATE controls and -(:c:type:`v4l2_subdev_video_ops`->s_stream() callback). These -interface elements must be present on the sub-device represents the -CSI-2 transmitter. - -The V4L2_CID_LINK_FREQ control is used to tell the receiver driver the -frequency (and not the symbol rate) of the link. The V4L2_CID_PIXEL_RATE -control may be used by the receiver to obtain the pixel rate the transmitter -uses. The :c:type:`v4l2_subdev_video_ops`->s_stream() callback provides an -ability to start and stop the stream. - -The value of the V4L2_CID_PIXEL_RATE is calculated as follows:: - - pixel_rate = link_freq * 2 * nr_of_lanes * 16 / k / bits_per_sample - -where - -.. list-table:: variables in pixel rate calculation - :header-rows: 1 - - * - variable or constant - - description - * - link_freq - - The value of the V4L2_CID_LINK_FREQ integer64 menu item. - * - nr_of_lanes - - Number of data lanes used on the CSI-2 link. This can - be obtained from the OF endpoint configuration. - * - 2 - - Two bits are transferred per clock cycle per lane. - * - bits_per_sample - - Number of bits per sample. - * - k - - 16 for D-PHY and 7 for C-PHY - -The transmitter drivers must, if possible, configure the CSI-2 -transmitter to *LP-11 mode* whenever the transmitter is powered on but -not active, and maintain *LP-11 mode* until stream on. Only at stream -on should the transmitter activate the clock on the clock lane and -transition to *HS mode*. - -Some transmitters do this automatically but some have to be explicitly -programmed to do so, and some are unable to do so altogether due to -hardware constraints. - -Stopping the transmitter -^^^^^^^^^^^^^^^^^^^^^^^^ - -A transmitter stops sending the stream of images as a result of -calling the ``.s_stream()`` callback. Some transmitters may stop the -stream at a frame boundary whereas others stop immediately, -effectively leaving the current frame unfinished. The receiver driver -should not make assumptions either way, but function properly in both -cases. - -Receiver drivers ----------------- - -Before the receiver driver may enable the CSI-2 transmitter by using -the :c:type:`v4l2_subdev_video_ops`->s_stream(), it must have powered -the transmitter up by using the -:c:type:`v4l2_subdev_core_ops`->s_power() callback. This may take -place either indirectly by using :c:func:`v4l2_pipeline_pm_get` or -directly. - -Formats -------- - -The media bus pixel codes document parallel formats. Should the pixel data be -transported over a serial bus, the media bus pixel code that describes a -parallel format that transfers a sample on a single clock cycle is used. diff --git a/Documentation/driver-api/media/index.rst b/Documentation/driver-api/media/index.rst index 813d7db59da7..08e206567408 100644 --- a/Documentation/driver-api/media/index.rst +++ b/Documentation/driver-api/media/index.rst @@ -37,7 +37,7 @@ Documentation/userspace-api/media/index.rst rc-core mc-core cec-core - csi2 + tx-rx camera-sensor drivers/index diff --git a/Documentation/driver-api/media/tx-rx.rst b/Documentation/driver-api/media/tx-rx.rst new file mode 100644 index 000000000000..e1e9258dd862 --- /dev/null +++ b/Documentation/driver-api/media/tx-rx.rst @@ -0,0 +1,133 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _transmitter-receiver: + +Pixel data transmitter and receiver drivers +=========================================== + +V4L2 supports various devices that transmit and receive pixel data. Examples of +these devices include a camera sensor, a TV tuner and a parallel or a CSI-2 +receiver in an SoC. + +Bus types +--------- + +The following busses are the most common. This section discusses these two only. + +MIPI CSI-2 +^^^^^^^^^^ + +CSI-2 is a data bus intended for transferring images from cameras to +the host SoC. It is defined by the `MIPI alliance`_. + +.. _`MIPI alliance`: https://www.mipi.org/ + +Parallel +^^^^^^^^ + +`BT.601`_ and `BT.656`_ are the most common parallel busses. + +.. _`BT.601`: https://en.wikipedia.org/wiki/Rec._601 +.. _`BT.656`: https://en.wikipedia.org/wiki/ITU-R_BT.656 + +Transmitter drivers +------------------- + +Transmitter drivers generally need to provide the receiver drivers with the +configuration of the transmitter. What is required depends on the type of the +bus. These are common for both busses. + +Media bus pixel code +^^^^^^^^^^^^^^^^^^^^ + +See :ref:`v4l2-mbus-pixelcode`. + +Link frequency +^^^^^^^^^^^^^^ + +The :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` control is used to tell the +receiver the frequency of the bus (i.e. it is not the same as the symbol rate). + +``.s_stream()`` callback +^^^^^^^^^^^^^^^^^^^^^^^^ + +The struct struct v4l2_subdev_video_ops->s_stream() callback is used by the +receiver driver to control the transmitter driver's streaming state. + + +CSI-2 transmitter drivers +------------------------- + +Pixel rate +^^^^^^^^^^ + +The pixel rate on the bus is calculated as follows:: + + pixel_rate = link_freq * 2 * nr_of_lanes * 16 / k / bits_per_sample + +where + +.. list-table:: variables in pixel rate calculation + :header-rows: 1 + + * - variable or constant + - description + * - link_freq + - The value of the ``V4L2_CID_LINK_FREQ`` integer64 menu item. + * - nr_of_lanes + - Number of data lanes used on the CSI-2 link. This can + be obtained from the OF endpoint configuration. + * - 2 + - Data is transferred on both rising and falling edge of the signal. + * - bits_per_sample + - Number of bits per sample. + * - k + - 16 for D-PHY and 7 for C-PHY + +.. note:: + + The pixel rate calculated this way is **not** the same thing as the + pixel rate on the camera sensor's pixel array which is indicated by the + :ref:`V4L2_CID_PIXEL_RATE <v4l2-cid-pixel-rate>` control. + +LP-11 and LP-111 modes +^^^^^^^^^^^^^^^^^^^^^^ + +As part of transitioning to high speed mode, a CSI-2 transmitter typically +briefly sets the bus to LP-11 or LP-111 state, depending on the PHY. This period +may be as short as 100 µs, during which the receiver observes this state and +proceeds its own part of high speed mode transition. + +Most receivers are capable of autonomously handling this once the software has +configured them to do so, but there are receivers which require software +involvement in observing LP-11 or LP-111 state. 100 µs is a brief period to hit +in software, especially when there is no interrupt telling something is +happening. + +One way to address this is to configure the transmitter side explicitly to LP-11 +or LP-111 mode, which requires support from the transmitter hardware. This is +not universally available. Many devices return to this state once streaming is +stopped while the state after power-on is LP-00 or LP-000. + +The ``.pre_streamon()`` callback may be used to prepare a transmitter for +transitioning to streaming state, but not yet start streaming. Similarly, the +``.post_streamoff()`` callback is used to undo what was done by the +``.pre_streamon()`` callback. The caller of ``.pre_streamon()`` is thus required +to call ``.post_streamoff()`` for each successful call of ``.pre_streamon()``. + +In the context of CSI-2, the ``.pre_streamon()`` callback is used to transition +the transmitter to the LP-11 or LP-111 mode. This also requires powering on the +device, so this should be only done when it is needed. + +Receiver drivers that do not need explicit LP-11 or LP-111 mode setup are waived +from calling the two callbacks. + +Stopping the transmitter +^^^^^^^^^^^^^^^^^^^^^^^^ + +A transmitter stops sending the stream of images as a result of +calling the ``.s_stream()`` callback. Some transmitters may stop the +stream at a frame boundary whereas others stop immediately, +effectively leaving the current frame unfinished. The receiver driver +should not make assumptions either way, but function properly in both +cases. diff --git a/Documentation/driver-api/nfc/nfc-hci.rst b/Documentation/driver-api/nfc/nfc-hci.rst index eb8a1a14e919..f10fe53aa9fe 100644 --- a/Documentation/driver-api/nfc/nfc-hci.rst +++ b/Documentation/driver-api/nfc/nfc-hci.rst @@ -181,7 +181,7 @@ xmit_from_hci(): The llc must be registered with nfc before it can be used. Do that by calling:: - nfc_llc_register(const char *name, struct nfc_llc_ops *ops); + nfc_llc_register(const char *name, const struct nfc_llc_ops *ops); Again, note that the llc does not handle the physical link. It is thus very easy to mix any physical link with any llc for a given chip driver. diff --git a/Documentation/driver-api/thermal/nouveau_thermal.rst b/Documentation/driver-api/thermal/nouveau_thermal.rst index 79ece266cf6d..aa10db6df309 100644 --- a/Documentation/driver-api/thermal/nouveau_thermal.rst +++ b/Documentation/driver-api/thermal/nouveau_thermal.rst @@ -90,7 +90,7 @@ Bug reports ----------- Thermal management on Nouveau is new and may not work on all cards. If you have -inquiries, please ping mupuf on IRC (#nouveau, freenode). +inquiries, please ping mupuf on IRC (#nouveau, OFTC). Bug reports should be filled on Freedesktop's bug tracker. Please follow https://nouveau.freedesktop.org/wiki/Bugs diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst index 606eed8823ce..c663b6f97825 100644 --- a/Documentation/driver-api/vfio.rst +++ b/Documentation/driver-api/vfio.rst @@ -255,11 +255,13 @@ vfio_unregister_group_dev() respectively:: void vfio_init_group_dev(struct vfio_device *device, struct device *dev, const struct vfio_device_ops *ops); + void vfio_uninit_group_dev(struct vfio_device *device); int vfio_register_group_dev(struct vfio_device *device); void vfio_unregister_group_dev(struct vfio_device *device); The driver should embed the vfio_device in its own structure and call -vfio_init_group_dev() to pre-configure it before going to registration. +vfio_init_group_dev() to pre-configure it before going to registration +and call vfio_uninit_group_dev() after completing the un-registration. vfio_register_group_dev() indicates to the core to begin tracking the iommu_group of the specified dev and register the dev as owned by a VFIO bus driver. Once vfio_register_group_dev() returns it is possible for userspace to |