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| author | Kees Cook <kees+treewide@kernel.org> | 2026-09-02 15:31:14 -0700 |
|---|---|---|
| committer | Kees Cook <kees@kernel.org> | 2026-09-04 21:37:00 -0700 |
| commit | 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch) | |
| tree | c65086f9bdcd48c6360fb7cb4598bca084da1f32 /Documentation/admin-guide/media/vimc.rst | |
| download | linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip | |
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci
This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.
Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.
Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <kees+treewide@kernel.org>
Diffstat (limited to 'Documentation/admin-guide/media/vimc.rst')
| -rw-r--r-- | Documentation/admin-guide/media/vimc.rst | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/Documentation/admin-guide/media/vimc.rst b/Documentation/admin-guide/media/vimc.rst new file mode 100644 index 000000000..29d843a8d --- /dev/null +++ b/Documentation/admin-guide/media/vimc.rst @@ -0,0 +1,110 @@ +.. SPDX-License-Identifier: GPL-2.0 + +The Virtual Media Controller Driver (vimc) +========================================== + +The vimc driver emulates complex video hardware using the V4L2 API and the Media +API. It has a capture device and three subdevices: sensor, debayer and scaler. + +Topology +-------- + +The topology is hardcoded, although you could modify it in vimc-core and +recompile the driver to achieve your own topology. This is the default topology: + +.. _vimc_topology_graph: + +.. kernel-figure:: vimc.dot + :alt: Diagram of the default media pipeline topology + :align: center + + Media pipeline graph on vimc + +Configuring the topology +~~~~~~~~~~~~~~~~~~~~~~~~ + +Each subdevice will come with its default configuration (pixelformat, height, +width, ...). One needs to configure the topology in order to match the +configuration on each linked subdevice to stream frames through the pipeline. +If the configuration doesn't match, the stream will fail. The ``v4l-utils`` +package is a bundle of user-space applications, that comes with ``media-ctl`` and +``v4l2-ctl`` that can be used to configure the vimc configuration. This sequence +of commands fits for the default topology: + +.. code-block:: bash + + media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]' + media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]' + media-ctl -d platform:vimc -V '"Scaler":0[fmt:RGB888_1X24/640x480]' + media-ctl -d platform:vimc -V '"Scaler":0[crop:(100,50)/400x150]' + media-ctl -d platform:vimc -V '"Scaler":1[fmt:RGB888_1X24/300x700]' + v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=300,height=700 + v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81 + +Subdevices +---------- + +Subdevices define the behavior of an entity in the topology. Depending on the +subdevice, the entity can have multiple pads of type source or sink. + +vimc-sensor: + Generates images in several formats using video test pattern generator. + Exposes: + + * 1 Pad source + +vimc-lens: + Ancillary lens for a sensor. Supports auto focus control. Linked to + a vimc-sensor using an ancillary link. The lens supports FOCUS_ABSOLUTE + control. + +.. code-block:: bash + + media-ctl -p + ... + - entity 28: Lens A (0 pad, 0 link) + type V4L2 subdev subtype Lens flags 0 + device node name /dev/v4l-subdev6 + - entity 29: Lens B (0 pad, 0 link) + type V4L2 subdev subtype Lens flags 0 + device node name /dev/v4l-subdev7 + v4l2-ctl -d /dev/v4l-subdev7 -C focus_absolute + focus_absolute: 0 + + +vimc-debayer: + Transforms images in bayer format into a non-bayer format. + Exposes: + + * 1 Pad sink + * 1 Pad source + +vimc-scaler: + Re-size the image to meet the source pad resolution. E.g.: if the sync + pad is configured to 360x480 and the source to 1280x720, the image will + be stretched to fit the source resolution. Works for any resolution + within the vimc limitations (even shrinking the image if necessary). + Exposes: + + * 1 Pad sink + * 1 Pad source + +vimc-capture: + Exposes node /dev/videoX to allow userspace to capture the stream. + Exposes: + + * 1 Pad sink + * 1 Pad source + +Module options +-------------- + +Vimc has a module parameter to configure the driver. + +* ``allocator=<unsigned int>`` + + memory allocator selection, default is 0. It specifies the way buffers + will be allocated. + + - 0: vmalloc + - 1: dma-contig |
