[elrepo] el7: Intel Braswell i2c host adapter support

[Björn Gerhart]

> Am 16.01.2016 um 17:09 schrieb Phil Perry <phil at elrepo.org>:
> 
>> On 15/01/16 18:12, Phil Perry wrote:
>>> On 15/01/16 17:16, Akemi Yagi wrote:
>>>> On Fri, Jan 15, 2016 at 6:19 AM, Björn Gerhart <gerhart at posteo.de> wrote:
>>>> 
>>>> Hi folks,
>>>> 
>>>> afaik the el7 kernel yet doesn't support the i2c host adapter of the
>>>> Braswell chipset by Intel. However, it's possible to simply compile a newer
>>>> release (taken from 3.19) of the i2c-i801 source code against the el7
>>>> kernel, and the module seems to work properly.
>>>> 
>>>> Is anybody out there already working on a kmod-i2c-i801 rpm package, or
>>>> otherwise: does it make sense to contribute it for general availability in
>>>> elrepo?
>>>> 
>>>> General rpmbuild knowledge available on my side, but not into contributing
>>>> for elrepo yet.
>>>> 
>>>> Best - Björn
>>> 
>>> We always welcome contributions.
>>> 
>>> You can send it to us as an srpm file. Or if you are comfortable with git,
>>> please submit it through our git ( https://github.com/elrepo/packages ) by
>>> following the procedure shown in http://elrepo.org/tiki/GitHub .
>>> 
>>> Thank you,
>>> Akemi
>> 
>> Or this is something I could pick up for you, if you're happy to assist
>> / test as you've already done most of the hard work by confirming that
>> the kernel-3.19 source code compiles cleanly and works.
>> 
>> The only thing I'd add is I'd rather run with code backported from a
>> kernel that is still supported longterm so we can easily continue to
>> backport any upstream security fixes and maintain the package in elrepo.
>> Thus, either 3.18 (if it contains support), or 4.1 (if it compiles
>> cleanly) kernels would be possible candidates. Your thoughts welcome as
>> you clearly have more experience with the module code than me.
> 
> I've built the package for you and just released it to the elrepo
> repository - it should show up on the mirrors shortly.
> 
> 
> kmod-i2c-i801-0.0-2.el7.elrepo.x86_64.rpm
> i2c-i801-kmod-0.0-2.el7.elrepo.src.rpm
> 
That's very kind of you Phil, thanks so much! What would be an appropriate versioning scheme to give a hint pointing to the origin module's source code revision in the kernel tree? I saw that e.g. the nct6775 module package uses the related git revision within the rpm release data.

> The required Braswell support first appeared in kernel-3.19, so I've
> backported the module from kernel-4.1.15. As 4.1 is a longterm kernel
> branch it should be easy to maintain the module for the supported life
> of that kernel.
> 
Sounds good.

> It's probably worth filing a bug with Red Hat requesting the module be
> updated in the RHEL kernel. State what you've done (i.e, simple backport
> from 4.1 works) as proof of principle and someone might pick it up for you.
> 
Thanks, I'll go for that.

> I'd appreciate if you could test and confirm the package works as expected.
> 
The package gets installed properly on my CentOS 7.2, and the module detects the hardware properly. Excellent!

Best - Björn