| Message ID | 20240709132906.3198927-9-dan.scally@ideasonboard.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add Arm Mali-C55 Image Signal Processor Driver | expand |
Hi Dan, Thank you for the patch. On Tue, Jul 09, 2024 at 02:28:56PM +0100, Daniel Scally wrote: > Add a documentation page for the mali-c55 driver, which gives a brief > overview of the hardware and explains how to use the driver's capture > devices and the crop/scaler functions. > > Acked-by: Nayden Kanchev <nayden.kanchev@arm.com> > Co-developed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> > Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> > Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > Changes in v6: > > - Minor formatting changes > > Changes in v5: > > - None > > Changes in v4: > - None > > Changes in v3: > - Documented the synchronised buffer sequence numbers (Sakari) > - Clarified that the downscale pipe cannot output raw data, the ISP'S > resolution limits and choice of media bus format code (Kieran) > > Changes in v2: > > - none > > .../admin-guide/media/mali-c55-graph.dot | 19 + > Documentation/admin-guide/media/mali-c55.rst | 340 ++++++++++++++++++ > .../admin-guide/media/v4l-drivers.rst | 1 + > 3 files changed, 360 insertions(+) > create mode 100644 Documentation/admin-guide/media/mali-c55-graph.dot > create mode 100644 Documentation/admin-guide/media/mali-c55.rst > > diff --git a/Documentation/admin-guide/media/mali-c55-graph.dot b/Documentation/admin-guide/media/mali-c55-graph.dot > new file mode 100644 > index 000000000000..0775ba42bf4c > --- /dev/null > +++ b/Documentation/admin-guide/media/mali-c55-graph.dot > @@ -0,0 +1,19 @@ > +digraph board { > + rankdir=TB > + n00000001 [label="{{} | mali-c55 tpg\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green] > + n00000001:port0 -> n00000003:port0 [style=dashed] > + n00000003 [label="{{<port0> 0} | mali-c55 isp\n/dev/v4l-subdev1 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green] > + n00000003:port1 -> n00000007:port0 [style=bold] > + n00000003:port2 -> n00000007:port2 [style=bold] > + n00000003:port1 -> n0000000b:port0 [style=bold] > + n00000007 [label="{{<port0> 0 | <port2> 2} | mali-c55 resizer fr\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] > + n00000007:port1 -> n0000000e [style=bold] > + n0000000b [label="{{<port0> 0} | mali-c55 resizer ds\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] > + n0000000b:port1 -> n00000012 [style=bold] > + n0000000e [label="mali-c55 fr\n/dev/video0", shape=box, style=filled, fillcolor=yellow] > + n00000012 [label="mali-c55 ds\n/dev/video1", shape=box, style=filled, fillcolor=yellow] > + n00000022 [label="{{<port0> 0} | csi2-rx\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] > + n00000022:port1 -> n00000003:port0 > + n00000027 [label="{{} | imx415 1-001a\n/dev/v4l-subdev5 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green] > + n00000027:port0 -> n00000022:port0 [style=bold] > +} > \ No newline at end of file > diff --git a/Documentation/admin-guide/media/mali-c55.rst b/Documentation/admin-guide/media/mali-c55.rst > new file mode 100644 > index 000000000000..72cdded507b3 > --- /dev/null > +++ b/Documentation/admin-guide/media/mali-c55.rst > @@ -0,0 +1,340 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +========================================== > +ARM Mali-C55 Image Signal Processor driver > +========================================== > + > +Introduction > +============ > + > +This file documents the driver for ARM's Mali-C55 Image Signal Processor. The > +driver is located under drivers/media/platform/arm/mali-c55. > + > +The Mali-C55 ISP receives data in either raw Bayer format or RGB/YUV format from > +sensors through either a parallel interface or a memory bus before processing it > +and outputting it through an internal DMA engine. Two output pipelines are > +possible (though one may not be fitted, depending on the implementation). These > +are referred to as "Full resolution" and "Downscale", but the naming is historic > +and both pipes are capable of cropping/scaling operations. The full resolution > +pipe is also capable of outputting RAW data, bypassing much of the ISP's > +processing. The downscale pipe cannot output RAW data. An integrated test > +pattern generator can be used to drive the ISP and produce image data in the > +absence of a connected camera sensor. The driver module is named mali_c55, and > +is enabled through the CONFIG_VIDEO_MALI_C55 config option. > + > +The driver implements V4L2, Media Controller and V4L2 Subdevice interfaces and > +expects camera sensors connected to the ISP to have V4L2 subdevice interfaces. > + > +Mali-C55 ISP hardware > +===================== > + > +A high level functional view of the Mali-C55 ISP is presented below. The ISP > +takes input from either a live source or through a DMA engine for memory input, > +depending on the SoC integration.:: > + > + +---------+ +----------+ +--------+ > + | Sensor |--->| CSI-2 Rx | "Full Resolution" | DMA | > + +---------+ +----------+ |\ Output +--->| Writer | > + | | \ | +--------+ > + | | \ +----------+ +------+---> Streaming I/O > + +------------+ +------->| | | | | > + | | | |-->| Mali-C55 |--+ > + | DMA Reader |--------------->| | | ISP | | > + | | | / | | | +---> Streaming I/O > + +------------+ | / +----------+ | | > + |/ +------+ > + | +--------+ > + +--->| DMA | > + "Downscaled" | Writer | > + Output +--------+ > + > +Media Controller Topology > +========================= > + > +An example of the ISP's topology (as implemented in a system with an IMX415 > +camera sensor and generic CSI-2 receiver) is below: > + > + > +.. kernel-figure:: mali-c55-graph.dot > + :alt: mali-c55-graph.dot > + :align: center > + > +The driver has 4 V4L2 subdevices: > + > +- `mali_c55 isp`: Responsible for configuring input crop and color space > + conversion > +- `mali_c55 tpg`: The test pattern generator, emulating a camera sensor. > +- `mali_c55 resizer fr`: The Full-Resolution pipe resizer > +- `mali_c55 resizer ds`: The Downscale pipe resizer > + > +The driver has 2 V4L2 video devices: > + > +- `mali-c55 fr`: The full-resolution pipe's capture device > +- `mali-c55 ds`: The downscale pipe's capture device > + > +Frame sequences are synchronised across to two capture devices, meaning if one > +pipe is started later than the other the sequence numbers returned in its > +buffers will match those of the other pipe rather than starting from zero. > + > +Idiosyncrasies > +-------------- > + > +**mali-c55 isp** > +The `mali-c55 isp` subdevice has a single sink pad to which all sources of data > +should be connected. The active source is selected by enabling the appropriate > +media link and disabling all others. The ISP has two source pads, reflecting the > +different paths through which it can internally route data. Tap points within > +the ISP allow users to divert data to avoid processing by some or all of the > +hardware's processing steps. The diagram below is intended only to highlight how > +the bypassing works and is not a true reflection of those processing steps; for > +a high-level functional block diagram see ARM's developer page for the > +ISP [3]_:: > + > + +--------------------------------------------------------------+ > + | Possible Internal ISP Data Routes | > + | +------------+ +----------+ +------------+ | > + +---+ | | | | | Colour | +---+ > + | 0 |--+-->| Processing |->| Demosaic |->| Space |--->| 1 | > + +---+ | | | | | | Conversion | +---+ > + | | +------------+ +----------+ +------------+ | > + | | +---+ > + | +---------------------------------------------------| 2 | > + | +---+ > + | | > + +--------------------------------------------------------------+ > + > + > +.. flat-table:: > + :header-rows: 1 > + > + * - Pad > + - Direction > + - Purpose > + > + * - 0 > + - sink > + - Data input, connected to the TPG and camera sensors > + > + * - 1 > + - source > + - RGB/YUV data, connected to the FR and DS V4L2 subdevices > + > + * - 2 > + - source > + - RAW bayer data, connected to the FR V4L2 subdevices > + > +The ISP is limited to both input and output resolutions between 640x480 and > +8192x8192, and this is reflected in the ISP and resizer subdevice's .set_fmt() > +operations. > + > +**mali-c55 resizer fr** > +The `mali-c55 resizer fr` subdevice has two _sink_ pads to reflect the different > +insertion points in the hardware (either RAW or demosaiced data): > + > +.. flat-table:: > + :header-rows: 1 > + > + * - Pad > + - Direction > + - Purpose > + > + * - 0 > + - sink > + - Data input connected to the ISP's demosaiced stream. > + > + * - 1 > + - source > + - Data output connected to the capture video device > + > + * - 2 > + - sink > + - Data input connected to the ISP's raw data stream > + > +The data source in use is selected through the routing API; two routes each of a > +single stream are available: > + > +.. flat-table:: > + :header-rows: 1 > + > + * - Sink Pad > + - Source Pad > + - Purpose > + > + * - 0 > + - 1 > + - Demosaiced data route > + > + * - 2 > + - 1 > + - Raw data route > + > + > +If the demosaiced route is active then the FR pipe is only capable of output > +in RGB/YUV formats. If the raw route is active then the output reflects the > +input (which may be either Bayer or RGB/YUV data). > + > +Using the driver to capture video > +================================= > + > +Using the media controller APIs we can configure the input source and ISP to > +capture images in a variety of formats. In the examples below, configuring the > +media graph is done with the v4l-utils [1]_ package's media-ctl utility. > +Capturing the images is done with yavta [2]_. > + > +Configuring the input source > +---------------------------- > + > +The first step is to set the input source that we wish by enabling the correct > +media link. Using the example topology above, we can select the TPG as follows: > + > +.. code-block:: none > + > + media-ctl -l "'lte-csi2-rx':1->'mali-c55 isp':0[0]" > + media-ctl -l "'mali-c55 tpg':0->'mali-c55 isp':0[1]" > + > +Configuring which video devices will stream data > +------------------------------------------------ > + > +The driver will wait for all video devices to have their VIDIOC_STREAMON ioctl > +called before it tells the sensor to start streaming. To facilitate this we need > +to enable links to the video devices that we want to use. In the example below > +we enable the links to both of the image capture video devices > + > +.. code-block:: none > + > + media-ctl -l "'mali-c55 resizer fr':1->'mali-c55 fr':0[1]" > + media-ctl -l "'mali-c55 resizer ds':1->'mali-c55 ds':0[1]" > + > +Capturing bayer data from the source and processing to RGB/YUV > +-------------------------------------------------------------- > + > +To capture 1920x1080 bayer data from the source and push it through the ISP's > +full processing pipeline, we configure the data formats appropriately on the > +source, ISP and resizer subdevices and set the FR resizer's routing to select > +processed data. The media bus format on the resizer's source pad will be either > +RGB121212_1X36 or YUV10_1X30, depending on whether you want to capture RGB or > +YUV. The ISP's debayering block outputs RGB data natively, setting the source > +pad format to YUV10_1X30 enables the colour space conversion block. > + > +In this example we target RGB565 output, so select RGB121212_1X36 as the resizer > +source pad's format: > + > +.. code-block:: none > + > + # Set formats on the TPG and ISP > + media-ctl -V "'mali-c55 tpg':0[fmt:SRGGB20_1X20/1920x1080]" > + media-ctl -V "'mali-c55 isp':0[fmt:SRGGB20_1X20/1920x1080]" > + media-ctl -V "'mali-c55 isp':1[fmt:SRGGB20_1X20/1920x1080]" > + > + # Set routing on the FR resizer > + media-ctl -R "'mali-c55 resizer fr'[0/0->1/0[1],2/0->1/0[0]]" > + > + # Set format on the resizer, must be done AFTER the routing. > + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/1920x1080]" > + > +The downscale output can also be used to stream data at the same time. In this > +case since only processed data can be captured through the downscale output no > +routing need be set: > + > +.. code-block:: none > + > + # Set format on the resizer > + media-ctl -V "'mali-c55 resizer ds':1[fmt:RGB121212_1X36/1920x1080]" > + > +Following which images can be captured from both the FR and DS output's video > +devices (simultaneously, if desired): > + > +.. code-block:: none > + > + yavta -f RGB565 -s 1920x1080 -c10 /dev/video0 > + yavta -f RGB565 -s 1920x1080 -c10 /dev/video1 > + > +Cropping the image > +~~~~~~~~~~~~~~~~~~ > + > +Both the full resolution and downscale pipes can crop to a minimum resolution of > +640x480. To crop the image simply configure the resizer's sink pad's crop and > +compose rectangles and set the format on the video device: > + > +.. code-block:: none > + > + media-ctl -V "'mali-c55 resizer fr':0[fmt:RGB121212_1X36/1920x1080 crop:(480,270)/640x480 compose:(0,0)/640x480]" > + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/640x480]" > + yavta -f RGB565 -s 640x480 -c10 /dev/video0 > + > +Downscaling the image > +~~~~~~~~~~~~~~~~~~~~~ > + > +Both the full resolution and downscale pipes can downscale the image by up to 8x > +provided the minimum 640x480 output resolution is adhered to. For the best image > +result the scaling ratio for each direction should be the same. To configure > +scaling we use the compose rectangle on the resizer's sink pad: > + > +.. code-block:: none > + > + media-ctl -V "'mali-c55 resizer fr':0[fmt:RGB121212_1X36/1920x1080 crop:(0,0)/1920x1080 compose:(0,0)/640x480]" > + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/640x480]" > + yavta -f RGB565 -s 640x480 -c10 /dev/video0 > + > +Capturing images in YUV formats > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +If we need to output YUV data rather than RGB the color space conversion block > +needs to be active, which is achieved by setting MEDIA_BUS_FMT_YUV10_1X30 on the > +resizer's source pad. We can then configure a capture format like NV12 (here in > +its multi-planar variant) > + > +.. code-block:: none > + > + media-ctl -V "'mali-c55 resizer fr':1[fmt:YUV10_1X30/1920x1080]" > + yavta -f NV12M -s 1920x1080 -c10 /dev/video0 > + > +Capturing RGB data from the source and processing it with the resizers > +---------------------------------------------------------------------- > + > +The Mali-C55 ISP can work with sensors capable of outputting RGB data. In this > +case although none of the image quality blocks would be used it can still > +crop/scale the data in the usual way. For this reason RGB data input to the ISP > +still goes through the ISP subdevice's pad 1 to the resizer. > + > +To achieve this, the ISP's sink pad's format is set to > +MEDIA_BUS_FMT_RGB202020_1X60 - this reflects the format that data must be in to > +work with the ISP. Converting the camera sensor's output to that format is the > +responsibility of external hardware. > + > +In this example we ask the test pattern generator to give us RGB data instead of > +bayer. > + > +.. code-block:: none > + > + media-ctl -V "'mali-c55 tpg':0[fmt:RGB202020_1X60/1920x1080]" > + media-ctl -V "'mali-c55 isp':0[fmt:RGB202020_1X60/1920x1080]" > + > +Cropping or scaling the data can be done in exactly the same way as outlined > +earlier. > + > +Capturing raw data from the source and outputting it unmodified > +----------------------------------------------------------------- > + > +The ISP can additionally capture raw data from the source and output it on the > +full resolution pipe only, completely unmodified. In this case the downscale > +pipe can still process the data normally and be used at the same time. > + > +To configure raw bypass the FR resizer's subdevice's routing table needs to be > +configured, followed by formats in the appropriate places: > + > +.. code-block:: none > + > + media-ctl -R "'mali-c55 resizer fr'[0/0->1/0[0],2/0->1/0[1]]" > + media-ctl -V "'mali-c55 isp':0[fmt:RGB202020_1X60/1920x1080]" > + media-ctl -V "'mali-c55 resizer fr':2[fmt:RGB202020_1X60/1920x1080]" > + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB202020_1X60/1920x1080]" > + > + # Set format on the video device and stream > + yavta -f RGB565 -s 1920x1080 -c10 /dev/video0 > + > +References > +========== > +.. [1] https://git.linuxtv.org/v4l-utils.git/ > +.. [2] https://git.ideasonboard.org/yavta.git > +.. [3] https://developer.arm.com/Processors/Mali-C55 > diff --git a/Documentation/admin-guide/media/v4l-drivers.rst b/Documentation/admin-guide/media/v4l-drivers.rst > index 4120eded9a13..1d9485860d93 100644 > --- a/Documentation/admin-guide/media/v4l-drivers.rst > +++ b/Documentation/admin-guide/media/v4l-drivers.rst > @@ -18,6 +18,7 @@ Video4Linux (V4L) driver-specific documentation > ipu3 > ipu6-isys > ivtv > + mali-c55 > mgb4 > omap3isp > omap4_camera
diff --git a/Documentation/admin-guide/media/mali-c55-graph.dot b/Documentation/admin-guide/media/mali-c55-graph.dot new file mode 100644 index 000000000000..0775ba42bf4c --- /dev/null +++ b/Documentation/admin-guide/media/mali-c55-graph.dot @@ -0,0 +1,19 @@ +digraph board { + rankdir=TB + n00000001 [label="{{} | mali-c55 tpg\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green] + n00000001:port0 -> n00000003:port0 [style=dashed] + n00000003 [label="{{<port0> 0} | mali-c55 isp\n/dev/v4l-subdev1 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green] + n00000003:port1 -> n00000007:port0 [style=bold] + n00000003:port2 -> n00000007:port2 [style=bold] + n00000003:port1 -> n0000000b:port0 [style=bold] + n00000007 [label="{{<port0> 0 | <port2> 2} | mali-c55 resizer fr\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] + n00000007:port1 -> n0000000e [style=bold] + n0000000b [label="{{<port0> 0} | mali-c55 resizer ds\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] + n0000000b:port1 -> n00000012 [style=bold] + n0000000e [label="mali-c55 fr\n/dev/video0", shape=box, style=filled, fillcolor=yellow] + n00000012 [label="mali-c55 ds\n/dev/video1", shape=box, style=filled, fillcolor=yellow] + n00000022 [label="{{<port0> 0} | csi2-rx\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green] + n00000022:port1 -> n00000003:port0 + n00000027 [label="{{} | imx415 1-001a\n/dev/v4l-subdev5 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green] + n00000027:port0 -> n00000022:port0 [style=bold] +} \ No newline at end of file diff --git a/Documentation/admin-guide/media/mali-c55.rst b/Documentation/admin-guide/media/mali-c55.rst new file mode 100644 index 000000000000..72cdded507b3 --- /dev/null +++ b/Documentation/admin-guide/media/mali-c55.rst @@ -0,0 +1,340 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================== +ARM Mali-C55 Image Signal Processor driver +========================================== + +Introduction +============ + +This file documents the driver for ARM's Mali-C55 Image Signal Processor. The +driver is located under drivers/media/platform/arm/mali-c55. + +The Mali-C55 ISP receives data in either raw Bayer format or RGB/YUV format from +sensors through either a parallel interface or a memory bus before processing it +and outputting it through an internal DMA engine. Two output pipelines are +possible (though one may not be fitted, depending on the implementation). These +are referred to as "Full resolution" and "Downscale", but the naming is historic +and both pipes are capable of cropping/scaling operations. The full resolution +pipe is also capable of outputting RAW data, bypassing much of the ISP's +processing. The downscale pipe cannot output RAW data. An integrated test +pattern generator can be used to drive the ISP and produce image data in the +absence of a connected camera sensor. The driver module is named mali_c55, and +is enabled through the CONFIG_VIDEO_MALI_C55 config option. + +The driver implements V4L2, Media Controller and V4L2 Subdevice interfaces and +expects camera sensors connected to the ISP to have V4L2 subdevice interfaces. + +Mali-C55 ISP hardware +===================== + +A high level functional view of the Mali-C55 ISP is presented below. The ISP +takes input from either a live source or through a DMA engine for memory input, +depending on the SoC integration.:: + + +---------+ +----------+ +--------+ + | Sensor |--->| CSI-2 Rx | "Full Resolution" | DMA | + +---------+ +----------+ |\ Output +--->| Writer | + | | \ | +--------+ + | | \ +----------+ +------+---> Streaming I/O + +------------+ +------->| | | | | + | | | |-->| Mali-C55 |--+ + | DMA Reader |--------------->| | | ISP | | + | | | / | | | +---> Streaming I/O + +------------+ | / +----------+ | | + |/ +------+ + | +--------+ + +--->| DMA | + "Downscaled" | Writer | + Output +--------+ + +Media Controller Topology +========================= + +An example of the ISP's topology (as implemented in a system with an IMX415 +camera sensor and generic CSI-2 receiver) is below: + + +.. kernel-figure:: mali-c55-graph.dot + :alt: mali-c55-graph.dot + :align: center + +The driver has 4 V4L2 subdevices: + +- `mali_c55 isp`: Responsible for configuring input crop and color space + conversion +- `mali_c55 tpg`: The test pattern generator, emulating a camera sensor. +- `mali_c55 resizer fr`: The Full-Resolution pipe resizer +- `mali_c55 resizer ds`: The Downscale pipe resizer + +The driver has 2 V4L2 video devices: + +- `mali-c55 fr`: The full-resolution pipe's capture device +- `mali-c55 ds`: The downscale pipe's capture device + +Frame sequences are synchronised across to two capture devices, meaning if one +pipe is started later than the other the sequence numbers returned in its +buffers will match those of the other pipe rather than starting from zero. + +Idiosyncrasies +-------------- + +**mali-c55 isp** +The `mali-c55 isp` subdevice has a single sink pad to which all sources of data +should be connected. The active source is selected by enabling the appropriate +media link and disabling all others. The ISP has two source pads, reflecting the +different paths through which it can internally route data. Tap points within +the ISP allow users to divert data to avoid processing by some or all of the +hardware's processing steps. The diagram below is intended only to highlight how +the bypassing works and is not a true reflection of those processing steps; for +a high-level functional block diagram see ARM's developer page for the +ISP [3]_:: + + +--------------------------------------------------------------+ + | Possible Internal ISP Data Routes | + | +------------+ +----------+ +------------+ | + +---+ | | | | | Colour | +---+ + | 0 |--+-->| Processing |->| Demosaic |->| Space |--->| 1 | + +---+ | | | | | | Conversion | +---+ + | | +------------+ +----------+ +------------+ | + | | +---+ + | +---------------------------------------------------| 2 | + | +---+ + | | + +--------------------------------------------------------------+ + + +.. flat-table:: + :header-rows: 1 + + * - Pad + - Direction + - Purpose + + * - 0 + - sink + - Data input, connected to the TPG and camera sensors + + * - 1 + - source + - RGB/YUV data, connected to the FR and DS V4L2 subdevices + + * - 2 + - source + - RAW bayer data, connected to the FR V4L2 subdevices + +The ISP is limited to both input and output resolutions between 640x480 and +8192x8192, and this is reflected in the ISP and resizer subdevice's .set_fmt() +operations. + +**mali-c55 resizer fr** +The `mali-c55 resizer fr` subdevice has two _sink_ pads to reflect the different +insertion points in the hardware (either RAW or demosaiced data): + +.. flat-table:: + :header-rows: 1 + + * - Pad + - Direction + - Purpose + + * - 0 + - sink + - Data input connected to the ISP's demosaiced stream. + + * - 1 + - source + - Data output connected to the capture video device + + * - 2 + - sink + - Data input connected to the ISP's raw data stream + +The data source in use is selected through the routing API; two routes each of a +single stream are available: + +.. flat-table:: + :header-rows: 1 + + * - Sink Pad + - Source Pad + - Purpose + + * - 0 + - 1 + - Demosaiced data route + + * - 2 + - 1 + - Raw data route + + +If the demosaiced route is active then the FR pipe is only capable of output +in RGB/YUV formats. If the raw route is active then the output reflects the +input (which may be either Bayer or RGB/YUV data). + +Using the driver to capture video +================================= + +Using the media controller APIs we can configure the input source and ISP to +capture images in a variety of formats. In the examples below, configuring the +media graph is done with the v4l-utils [1]_ package's media-ctl utility. +Capturing the images is done with yavta [2]_. + +Configuring the input source +---------------------------- + +The first step is to set the input source that we wish by enabling the correct +media link. Using the example topology above, we can select the TPG as follows: + +.. code-block:: none + + media-ctl -l "'lte-csi2-rx':1->'mali-c55 isp':0[0]" + media-ctl -l "'mali-c55 tpg':0->'mali-c55 isp':0[1]" + +Configuring which video devices will stream data +------------------------------------------------ + +The driver will wait for all video devices to have their VIDIOC_STREAMON ioctl +called before it tells the sensor to start streaming. To facilitate this we need +to enable links to the video devices that we want to use. In the example below +we enable the links to both of the image capture video devices + +.. code-block:: none + + media-ctl -l "'mali-c55 resizer fr':1->'mali-c55 fr':0[1]" + media-ctl -l "'mali-c55 resizer ds':1->'mali-c55 ds':0[1]" + +Capturing bayer data from the source and processing to RGB/YUV +-------------------------------------------------------------- + +To capture 1920x1080 bayer data from the source and push it through the ISP's +full processing pipeline, we configure the data formats appropriately on the +source, ISP and resizer subdevices and set the FR resizer's routing to select +processed data. The media bus format on the resizer's source pad will be either +RGB121212_1X36 or YUV10_1X30, depending on whether you want to capture RGB or +YUV. The ISP's debayering block outputs RGB data natively, setting the source +pad format to YUV10_1X30 enables the colour space conversion block. + +In this example we target RGB565 output, so select RGB121212_1X36 as the resizer +source pad's format: + +.. code-block:: none + + # Set formats on the TPG and ISP + media-ctl -V "'mali-c55 tpg':0[fmt:SRGGB20_1X20/1920x1080]" + media-ctl -V "'mali-c55 isp':0[fmt:SRGGB20_1X20/1920x1080]" + media-ctl -V "'mali-c55 isp':1[fmt:SRGGB20_1X20/1920x1080]" + + # Set routing on the FR resizer + media-ctl -R "'mali-c55 resizer fr'[0/0->1/0[1],2/0->1/0[0]]" + + # Set format on the resizer, must be done AFTER the routing. + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/1920x1080]" + +The downscale output can also be used to stream data at the same time. In this +case since only processed data can be captured through the downscale output no +routing need be set: + +.. code-block:: none + + # Set format on the resizer + media-ctl -V "'mali-c55 resizer ds':1[fmt:RGB121212_1X36/1920x1080]" + +Following which images can be captured from both the FR and DS output's video +devices (simultaneously, if desired): + +.. code-block:: none + + yavta -f RGB565 -s 1920x1080 -c10 /dev/video0 + yavta -f RGB565 -s 1920x1080 -c10 /dev/video1 + +Cropping the image +~~~~~~~~~~~~~~~~~~ + +Both the full resolution and downscale pipes can crop to a minimum resolution of +640x480. To crop the image simply configure the resizer's sink pad's crop and +compose rectangles and set the format on the video device: + +.. code-block:: none + + media-ctl -V "'mali-c55 resizer fr':0[fmt:RGB121212_1X36/1920x1080 crop:(480,270)/640x480 compose:(0,0)/640x480]" + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/640x480]" + yavta -f RGB565 -s 640x480 -c10 /dev/video0 + +Downscaling the image +~~~~~~~~~~~~~~~~~~~~~ + +Both the full resolution and downscale pipes can downscale the image by up to 8x +provided the minimum 640x480 output resolution is adhered to. For the best image +result the scaling ratio for each direction should be the same. To configure +scaling we use the compose rectangle on the resizer's sink pad: + +.. code-block:: none + + media-ctl -V "'mali-c55 resizer fr':0[fmt:RGB121212_1X36/1920x1080 crop:(0,0)/1920x1080 compose:(0,0)/640x480]" + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/640x480]" + yavta -f RGB565 -s 640x480 -c10 /dev/video0 + +Capturing images in YUV formats +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +If we need to output YUV data rather than RGB the color space conversion block +needs to be active, which is achieved by setting MEDIA_BUS_FMT_YUV10_1X30 on the +resizer's source pad. We can then configure a capture format like NV12 (here in +its multi-planar variant) + +.. code-block:: none + + media-ctl -V "'mali-c55 resizer fr':1[fmt:YUV10_1X30/1920x1080]" + yavta -f NV12M -s 1920x1080 -c10 /dev/video0 + +Capturing RGB data from the source and processing it with the resizers +---------------------------------------------------------------------- + +The Mali-C55 ISP can work with sensors capable of outputting RGB data. In this +case although none of the image quality blocks would be used it can still +crop/scale the data in the usual way. For this reason RGB data input to the ISP +still goes through the ISP subdevice's pad 1 to the resizer. + +To achieve this, the ISP's sink pad's format is set to +MEDIA_BUS_FMT_RGB202020_1X60 - this reflects the format that data must be in to +work with the ISP. Converting the camera sensor's output to that format is the +responsibility of external hardware. + +In this example we ask the test pattern generator to give us RGB data instead of +bayer. + +.. code-block:: none + + media-ctl -V "'mali-c55 tpg':0[fmt:RGB202020_1X60/1920x1080]" + media-ctl -V "'mali-c55 isp':0[fmt:RGB202020_1X60/1920x1080]" + +Cropping or scaling the data can be done in exactly the same way as outlined +earlier. + +Capturing raw data from the source and outputting it unmodified +----------------------------------------------------------------- + +The ISP can additionally capture raw data from the source and output it on the +full resolution pipe only, completely unmodified. In this case the downscale +pipe can still process the data normally and be used at the same time. + +To configure raw bypass the FR resizer's subdevice's routing table needs to be +configured, followed by formats in the appropriate places: + +.. code-block:: none + + media-ctl -R "'mali-c55 resizer fr'[0/0->1/0[0],2/0->1/0[1]]" + media-ctl -V "'mali-c55 isp':0[fmt:RGB202020_1X60/1920x1080]" + media-ctl -V "'mali-c55 resizer fr':2[fmt:RGB202020_1X60/1920x1080]" + media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB202020_1X60/1920x1080]" + + # Set format on the video device and stream + yavta -f RGB565 -s 1920x1080 -c10 /dev/video0 + +References +========== +.. [1] https://git.linuxtv.org/v4l-utils.git/ +.. [2] https://git.ideasonboard.org/yavta.git +.. [3] https://developer.arm.com/Processors/Mali-C55 diff --git a/Documentation/admin-guide/media/v4l-drivers.rst b/Documentation/admin-guide/media/v4l-drivers.rst index 4120eded9a13..1d9485860d93 100644 --- a/Documentation/admin-guide/media/v4l-drivers.rst +++ b/Documentation/admin-guide/media/v4l-drivers.rst @@ -18,6 +18,7 @@ Video4Linux (V4L) driver-specific documentation ipu3 ipu6-isys ivtv + mali-c55 mgb4 omap3isp omap4_camera