BeagleBoneBlack SPI hardware support (custom SPI driver) - cu-ecen-aeld/buildroot-assignments-base GitHub Wiki

Kernel and Device Tree modifications for BeagleBoneBlack SPI support

spi_no_idle.patch - https://github.com/cu-ecen-aeld/final-project-SundarKrishnakumar/blob/master/base_external/patches/linux/spi_no_idle.patch

Info: https://github.com/cu-ecen-aeld/final-project-SundarKrishnakumar/issues/13

devtree.patch - https://github.com/cu-ecen-aeld/final-project-SundarKrishnakumar/blob/master/base_external/patches/linux/devtree.patch

Info: https://github.com/cu-ecen-aeld/final-project-SundarKrishnakumar/issues/12

What is .patch file? You have made a few changes to the kernel and you want to share them with your team members, you can create something called a patch file that contains the just the changes you have made.

Creating your own patch file

spi_no_idle.patch creation is shown in a step-by-step manner below. Similar steps can be followed to create patch files for any new kernel modifications.

  • Change directory to the repository that contains the linux source code.
  • Before making our changes, we should checkout a new branch.
host$ cd bb-kernel/KERNEL
host$ git status
# On branch master
nothing to commit (working directory clean)

host$ git checkout -b patchdemo
host$ git status
# On branch patchdemo
nothing to commit (working directory clean)

(We have created a new branch called 'patchdemo' and have checked out to our new branch. Now we can start making changes to the kernel code.)

  • We are making changes to the file /arch/arm/mach-omap2/omap_hwmod_33xx_43xx_ipblock_data.c
  • We will be adding the following line to the variables 'am33xx_spi0_hwmod' and 'am33xx_spi1_hwmod'
.flags		= HWMOD_NO_IDLE // Do not idle the hwmod at all
  • Add the files that were modified and commit them
host$ git add ./arch/arm/mach-omap2/omap_hwmod_33xx_43xx_ipblock_data.c
host$ git commit -m"idling disabled for spi0 and spi1 hwmod"
  • Finally, we can create the patch file.
host$ git format-patch master --stdout > spi_no_idle.patch

(The spi_no_idle.patch file will be created in the current directory.)

  • If we inspect the file, we will see the changes that we made.