Commit c6f7b0f2 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
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doc-rst: dev-subdev: fix some format issues 



The conversion from DocBook made somethings look ugly.
Improve them.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 41dbe0c1

Documentation/linux_tv/media/v4l/dev-subdev.rst

+8 −8
Original line number Diff line number Diff line
@@ -118,14 +118,14 @@ every point in the pipeline explicitly. 
Drivers that implement the :ref:`media API <media-controller-intro>`

can expose pad-level image format configuration to applications. When

they do, applications can use the

:ref:`VIDIOC_SUBDEV_G_FMT` and

:ref:`VIDIOC_SUBDEV_G_FMT <VIDIOC_SUBDEV_G_FMT>` and

:ref:`VIDIOC_SUBDEV_S_FMT <VIDIOC_SUBDEV_G_FMT>` ioctls. to

negotiate formats on a per-pad basis.



Applications are responsible for configuring coherent parameters on the

whole pipeline and making sure that connected pads have compatible

formats. The pipeline is checked for formats mismatch at

:ref:`VIDIOC_STREAMON` time, and an ``EPIPE`` error

:ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` time, and an ``EPIPE`` error

code is then returned if the configuration is invalid.



Pad-level image format configuration support can be tested by calling
@@ -145,8 +145,8 @@ formats enumeration only. A format negotiation mechanism is required. 


Central to the format negotiation mechanism are the get/set format

operations. When called with the ``which`` argument set to

``V4L2_SUBDEV_FORMAT_TRY``, the

:ref:`VIDIOC_SUBDEV_G_FMT` and

:ref:`V4L2_SUBDEV_FORMAT_TRY <VIDIOC_SUBDEV_G_FMT>`, the

:ref:`VIDIOC_SUBDEV_G_FMT <VIDIOC_SUBDEV_G_FMT>` and

:ref:`VIDIOC_SUBDEV_S_FMT <VIDIOC_SUBDEV_G_FMT>` ioctls operate on

a set of formats parameters that are not connected to the hardware

configuration. Modifying those 'try' formats leaves the device state
@@ -155,7 +155,7 @@ and the hardware state stored in the device itself). 


While not kept as part of the device state, try formats are stored in

the sub-device file handles. A

:ref:`VIDIOC_SUBDEV_G_FMT` call will return

:ref:`VIDIOC_SUBDEV_G_FMT <VIDIOC_SUBDEV_G_FMT>` call will return

the last try format set *on the same sub-device file handle*. Several

applications querying the same sub-device at the same time will thus not

interact with each other.
@@ -443,7 +443,7 @@ selection will refer to the sink pad format dimensions instead. 
    :alt:    subdev-image-processing-crop.svg

    :align:  center



    Image processing in subdevs: simple crop example

    **Figure 4.5. Image processing in subdevs: simple crop example**



In the above example, the subdev supports cropping on its sink pad. To

configure it, the user sets the media bus format on the subdev's sink
@@ -460,7 +460,7 @@ pad. 
    :alt:    subdev-image-processing-scaling-multi-source.svg

    :align:  center



    Image processing in subdevs: scaling with multiple sources

    **Figure 4.6. Image processing in subdevs: scaling with multiple sources**



In this example, the subdev is capable of first cropping, then scaling

and finally cropping for two source pads individually from the resulting
@@ -476,7 +476,7 @@ an area at location specified by the source crop rectangle from it. 
    :alt:    subdev-image-processing-full.svg

    :align:  center



    Image processing in subdevs: scaling and composition with multiple sinks and sources

    **Figure 4.7. Image processing in subdevs: scaling and composition with multiple sinks and sources**



The subdev driver supports two sink pads and two source pads. The images

from both of the sink pads are individually cropped, then scaled and