topic Re: imx28 best kernel to use in i.MX Processors

imx28 best kernel to use

JeromeBaron — Wed, 08 Apr 2015 15:16:15 GMT

Hi everyone,

I have a custom board based on imx28evk. Im currently using LTIB with kernel imx_2.6.35_maintain branch from linux-2.6-imx.git - Freescale i.MX Linux Tree.

Now, I want to use backport driver to integrate a wl18xx chip. I found that backport 3.10.19 support kernel 2.6.38.

I have looked into the forum to find the different kernel tree that I could use and I'm a bit confused. I don't mind going further than 2.6.38 but I already made some changes in 2.6.35 and I'm afraid to redo this work again if I use a newer kernel. If possible, I would like to keep using LTIB and only change the kernel package I use. I don't know if it's possible... So far, here's the options I found:

Yocto

With machine "m28evk". According to the documentation, it use kernel linux-fscl, 3.17+.

I've nerver used Yocto, I don't know how to define custom board/pin definition. I think it would be a big change.

Newer kernel in linux-2.6-imx.git - Freescale i.MX Linux Tree

By looking at the file tree in different branches, I can see file like mach-m28evk.c which make me thinks the imx28evk is well supported.

It can be found in the branch imx_3.5.7_1.0.1_alpha, imx_3.0.35_xxxx, imx_3.0.15_xxxx and imx_3.0.101.

This looks interesting, but Im not sure if the imx28 is "well" supported in those branch. I mean that if I look at the commit history in imx_2.6.35_maintain there's commit related to MX28 until november 2013.

But some of the branch mentionned above, like imx_3.0.15 stopped in march 2012.

So I'm afraid that not every patch related to imx28 have been ported to those branch.

Mainline kernel

I saw a post that says the TX28 board is supported in the mainline kernel. I can see some specific board file, but I'm really not used with the new architecture and the custom borad file ".dts".

Does someone have experience by switching from LTIB 2.6.35 to any of those options? Any comment or advice?

Best regards,

Jerome

Re: imx28 best kernel to use

sinanakman — Wed, 08 Apr 2015 15:56:48 GMT

Hi Jerome

My suggestions is, unless you have a very good reason,

just stick to recent mainline kernel. It may take sometime

to learn new dts etc. but it will pay off. The imx28evk board

is supported in mainline kernel so you shouldn't need big

changes for your custom board. If you are just trying things

out you can build a root file system very quickly using buildroot.

Later on when you need something more extensive you can move

to a yocto based rootfs if you prefer. Vendor specific trees might

be useful for a feature perhaps not in the mainline yet but

from my experience using mainline kernel will save you lots of

time in the long run.

Hope this helps

Sinan Akman

Re: imx28 best kernel to use

JeromeBaron — Thu, 09 Apr 2015 12:52:21 GMT

Thanks for your answer. What do you mean by "need something more extensive" that will make me move to a Yocto based rootfs.

Is it if I need more package/apps on my rootfs? In my project, I don't need much, basic shell command, alsa_lib/tools package and wifi utilities.

Re: imx28 best kernel to use

sinanakman — Fri, 10 Apr 2015 17:08:57 GMT

Hi Jerome

For what you describe, buildroot should be fine. I am not a

Yocto expert but it offers some extended distro build features

such as inter-package dependencies, layered customization

etc. I don't think from the number of packages/applications

you will see much difference for your case. I would recommend

to use a mainline kernel and generate your root file system with

build root for your basic needs in your project.

Hope this helps.

Sinan Akman