Cameras in Embedded Systems: Device Tree and ACPI View
summary
Covers how camera subsystems map to firmware descriptions and what actually works today: Device Tree becomes the ARM-preferred mechanism around 2011 but V4L2 device tree support arrives over a year later, so the V4L2 async framework is used to solve probe ordering by registering notifiers and completing bindings once sensors and ISPs appear. ACPI gains DSD property and hierarchical extensions (since 5.1) and a firmware-node graph API plus V4L2 firmware-node API RFCs aim to give ACPI parity; camera-module power sequences, lens/flash links and required properties remain practical gaps.
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chapters (20)
- 0:00Intro
- 0:36A typical embedded system with a camera
- 4:17Image signal processors
- 5:05Video4 Linux and Media controller
- 6:15Example of a media graph
- 7:19Probing
- 7:54Media device setup
- 10:53V4L2 async example (ISP)
- 12:55V4L2 async (sensor)
- 15:57Device Tree standard and bindings
- 16:58Device tree graphs phandle properties can be used to refer to other nodes in the tree
- 18:07Sensor node
- 20:00ISP node board specific part
- 20:45OF graph API
- 24:11ACPI Device Specific Data
- 27:02fwnode property API
- 28:01Fwnode graph API
- 30:11Flash
- 33:17Camera module power on and power off sequences
- 40:34Firmware logistics
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