Book Image

Mastering Linux Device Driver Development

By : John Madieu
Book Image

Mastering Linux Device Driver Development

By: John Madieu

Overview of this book

Linux is one of the fastest-growing operating systems around the world, and in the last few years, the Linux kernel has evolved significantly to support a wide variety of embedded devices with its improved subsystems and a range of new features. With this book, you’ll find out how you can enhance your skills to write custom device drivers for your Linux operating system. Mastering Linux Device Driver Development provides complete coverage of kernel topics, including video and audio frameworks, that usually go unaddressed. You’ll work with some of the most complex and impactful Linux kernel frameworks, such as PCI, ALSA for SoC, and Video4Linux2, and discover expert tips and best practices along the way. In addition to this, you’ll understand how to make the most of frameworks such as NVMEM and Watchdog. Once you’ve got to grips with Linux kernel helpers, you’ll advance to working with special device types such as Multi-Function Devices (MFD) followed by video and audio device drivers. By the end of this book, you’ll be able to write feature-rich device drivers and integrate them with some of the most complex Linux kernel frameworks, including V4L2 and ALSA for SoC.
Table of Contents (19 chapters)
1
Section 1:Kernel Core Frameworks for Embedded Device Driver Development
6
Section 2: Multimedia and Power Saving in Embedded Linux Systems
13
Section 3: Staying Up to Date with Other Linux Kernel Subsystems

Chapter 8: Integrating with V4L2 Async and Media Controller Frameworks

Over time, media support has become a must and a saling argument for System on Chips (SoCs), which keep becoming more and more complex. The complexity of those media IP cores is such that grabbing sensor data requires a whole pipeline (made of several sub-devices) to be set up by the software. The asynchronous nature of a device tree-based system means the setup and probing of those sub-devices are not straightforward. Thus entered the async framework, which addresses the unordered probing of sub-devices in order for the media device to be popped on time, when all of the media sub-devices are ready. Last but not least, because of the complexity of the media pipe, it became necessary to find a way to ease the configuration of the sub-devices it is made of. Thus came the media controller framework, which wraps the whole media pipe in a single element, the media device. It comes with some abstractions, one of which...