BeagleBone patchset for mainline Linux kernel

5 Dec 2015

After my last post Build fbtft drivers for Linux 4.4 on BeagleBone Black, I was curious what patches are needed to run mainline Linux kernel on BeagleBoard. Here's what I've found so far:

Mainline Linux kernel

"Mainline" refers to Linus Torvald's linux.git repo hosted on kernel.org:
Kernel version currently in development is Linux 4.4
Linux 4.4 is now in the release candidate phase
Most recent release candidate is: Linux 4.4-rc3

Robert C. Nelson's bb-kernel repo

bb-kernel repo is maintained by the most excellent Robert C. Nelson:

"This git repo contains just scripts/patches to build a specific kernel for some ARM devices. The kernel source will be downloaded when you run any of the build scripts"

Most recent branch is: am33x-v4.4
Most recent tag: 4.4-rc3-bone0
build_kernel.sh will clone Linus Torvald's linux.git repo into ignore/linux-src dir
The repo in ignore/linux-src will then be cloned into KERNEL dir
BeagleBone patchset will then be applied to that KERNEL repo

Patchset for BeagleBone:

Robert maintains a BeagleBone patchset for the mainline Linux kernel
102 patches applied when I run the build script
patch.sh script calls:
- reverts () function to apply 1 patch
- ti () function to apply 24 patches for cpu_freq and 3 patches for iodelay
- pru ()function to apply 2 patches
- bbb_overlays () function to apply 44 patches
- beaglebone () function to apply 31 patches
- quieter () function to apply 1 patch

BeagleBone Cape Manager (bone_capemgr):

[PATCH 1/5] misc: Beaglebone capemanager by Pantelis Antoniou
Recent Google+ discussion about mainline and the current bone_capemgr patchset
eLinux wiki: capemgr
- in-kernel mechanism for dynamically loading Device Tree fragments from userspace.
- completely implemented in the kernel with no userspace component
- implementation is currently located in the BeagleBone kernel patch set at Linux 3.8 and Linux 4.1.
Device Tree Overlays from bb.org-overlays repo
slots: /sys/devices/platform/bone_capemgr/slots
enable/disable cmdline:
- bone_capemgr.enable_partno=
- bone_capemgr.disable_partno=

Workaround: Disable DMA for SPI driver:

bbb: add spi pio mode
- https://github.com/RobertCNelson/bb-kernel/commit/cef1661f6d27847b7a1f37ab6db2aec397e6388c
config: CONFIG_SPI_DEBUG is actually useful
- https://github.com/RobertCNelson/bb-kernel/commit/3596145f3ee2b0ddc7e1832257b1deea4db7afa2
config: spidev to module
- https://github.com/RobertCNelson/bb-kernel/commit/37a51d3db7c9ee4a500493ba9a189685dfcfaf7e

Related GitHub Gists:

bb-kernel am33x-v4.4: patches just bbb_overlays & beaglebone
- https://gist.github.com/pdp7/f314ba20db5eb2e91d65
BeagleBone Black am33x-v4.4 with fbtft drivers
- https://gist.github.com/pdp7/37b3c355ea18e13cfc79