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Just a warning if you do embedded work with Linux (RPi, Beaglebone, etc)... this guide doesn't cover the Devicetree APIs. Doesn't even acknowledge their existe

Just a warning if you do embedded work with Linux (RPi, Beaglebone, etc)... this guide doesn't cover the Devicetree APIs. Doesn't even acknowledge their existence.

eating555 5y ago
The author is pretty open to any kind of criticisms and suggestions. It would be great if you open an issue to inform him the missing contents.
- joezydeco 5y ago
  Already did
  - jserv 5y ago
    Thanks for submitting issue(s). The motivation of updating "The Linux Kernel Module Programming Guide" was for educational purpose. I agree with the idea to mention new kernel features such as Devicetree.
deleted 5y ago
[deleted]
tajustice1 5y ago
RPi is barely embedded work. It's almost always micro-desktop Linux.
- joezydeco 5y ago
  True. But there are some of us working on ARM platforms that aren't RPi that need to hack drivers. Anyone working with a SOM, for example, will want to customize the DT for their carrier board. And then your EE finds a cheaper controller chip somewhere. And then your display supplier switches captouch parts on you mid-production. Sorry, was I venting there? (And just a tip, don't break bad on the Pi here. For many people this is the only ARM platform worth working with. And definitely don't make fun of the lack of peripherals on the thing)
  - ndesaulniers 5y ago
    You're right. I was trying to write up a cpufreq driver for the Nintendo 3DS and found that LKMPG's complete lack of DT info astounding.
  - tajustice1 5y ago
    >True. But there are some of us working on ARM platforms that aren't RPi that need to hack drivers. Which has nothing to do with RPi or embedded systems... Not sure if I understand. >And just a tip, don't break bad on the Pi here. For many people this is the only ARM platform worth working with. Ugh... Cell phones? Or any of the zillion of ARM development boards out there.
matheusmoreira 5y ago
> this guide doesn't cover the Devicetree APIs Is there a guide for that?
- mkipper 5y ago
  Read the Documentation/devicetree directory in the kernel sources and look at how a few drivers implement their documented bindings. This isn't a snarky RTFM comment. The usage model file in the kernel documentation gives good motivation for what device trees are used for and their basic structure, and the APIs to pull data from them are straightforward enough that you can probably figure them out by looking at an example.

Just a warning if you do embedded work with Linux (RPi, Beaglebone, etc)... this guide doesn't cover the Devicetree APIs. Doesn't even acknowledge their existence.

eating555 5y ago

The author is pretty open to any kind of criticisms and suggestions. It would be great if you open an issue to inform him the missing contents.

joezydeco 5y ago
Already did
- jserv 5y ago
  Thanks for submitting issue(s). The motivation of updating "The Linux Kernel Module Programming Guide" was for educational purpose. I agree with the idea to mention new kernel features such as Devicetree.

deleted 5y ago

[deleted]

tajustice1 5y ago

RPi is barely embedded work. It's almost always micro-desktop Linux.

joezydeco 5y ago
True. But there are some of us working on ARM platforms that aren't RPi that need to hack drivers. Anyone working with a SOM, for example, will want to customize the DT for their carrier board. And then your EE finds a cheaper controller chip somewhere. And then your display supplier switches captouch parts on you mid-production. Sorry, was I venting there? (And just a tip, don't break bad on the Pi here. For many people this is the only ARM platform worth working with. And definitely don't make fun of the lack of peripherals on the thing)
- ndesaulniers 5y ago
  You're right. I was trying to write up a cpufreq driver for the Nintendo 3DS and found that LKMPG's complete lack of DT info astounding.
- tajustice1 5y ago
  >True. But there are some of us working on ARM platforms that aren't RPi that need to hack drivers. Which has nothing to do with RPi or embedded systems... Not sure if I understand. >And just a tip, don't break bad on the Pi here. For many people this is the only ARM platform worth working with. Ugh... Cell phones? Or any of the zillion of ARM development boards out there.

matheusmoreira 5y ago

> this guide doesn't cover the Devicetree APIs Is there a guide for that?

mkipper 5y ago
Read the Documentation/devicetree directory in the kernel sources and look at how a few drivers implement their documented bindings. This isn't a snarky RTFM comment. The usage model file in the kernel documentation gives good motivation for what device trees are used for and their basic structure, and the APIs to pull data from them are straightforward enough that you can probably figure them out by looking at an example.