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Asked: 2026-06-18T06:05:35+00:00

I need to add the MCP7941X RTC linux kernel driver to custom HW with

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I need to add the MCP7941X RTC linux kernel driver to custom HW with a TMS320DM368 DaVinci processor running embedded-linux 2.6. It seems this can be accomplished by adding one or more patches to the DS1307 RTC driver. As a linux newbie I’ve not added a patch to the kernel before but I am guessing what I need to do is make a plain text file from this, add the file to kernel/patches, and add a line to install the patch to the series file. I am also concerned about the following notes in this link:

patch depends on:
rtc: ds1307: comment and format cleanup 38f0a1072f
rtc: ds1307: simplify irq setup code f5af1f6ffe
rtc: ds1307: refactor chip_desc table c0920a32b7

Do these notes mean that I need to find and also add these patches to kernel/patches or should I be able to find a single latest and greatest patch that includes the MCP7941X?

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1 Answer

  1. Editorial Team

    Welcome to the sometimes frustrating but always challenging world of Linux kernel patch juggling! Unless you find someone who’s already done what you’re trying to do, you’re pretty much on your own to apply these patches and test the results. Yes, those lines likely indicate patches that must be applied before the patch in question will apply cleanly, but it’s easy enough to figure it out.

    You didn’t say where you got your kernel or what it is based on, nor how you are building it. But if you’re just building a 2.6 kernel manually from the command line, I don’t think patches are applied automatically. But patches are easy enough to apply and test out. Something like:

    $ cd top/level/kernel/dir

    $ patch -p1 < your.patch

    Note that often you can just feed patch the e-mail without having to format anything. Just try it. patch is smart enough to find the actual formatted patch within the e-mail.

    You can use the quilt tool to apply patches to a query. The man page and web searches should make that easy.

    Unfortunately, as I said, unless you happen to find someone who already has done that, you won’t know the results until you try it and test it. That’s the nature of open source.

    Finally, in case you don’t speak ‘git’, those 10-digit hex numbers after those patches in the dependency list above refer to git “commits” also called “hashes”. Of course, they refer to some specific git kernel repository that isn’t identified in your e-mail. Again, the man pages for git and the internet should guide you there.

    And as sawdust pointed out, if you don’t already have the driver configured into your kernel, you might need to add it using ‘make menuconfig’ in the kernel configuration. And if the driver isn’t there, well, that’s another story altogether, and my book “Embedded Linux Primer” has a section detailing how to add config snippets to the kernel build system to add new drivers that aren’t already present in your kernel tree.

    Good luck.

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