[PATCH 21.02] ipq806x: backport cpufreq changes to 5.4

[Shane Synan]

On 6/27/21 6:10 PM, Ansuel Smith wrote:
> Il giorno dom 27 giu 2021 alle ore 23:41 Baptiste Jonglez
> <baptiste at bitsofnetworks.org> ha scritto:
>>
>> Ansuel, do you have any feedback on this backport?  It seems to help things.
>>
> It's good but consider that also the dts changes are required and also there
> is a pending pr that has to be merged or ipq8065 device will run at lower speed.
> The new cpufreq have changed the node definition
> This is the pr I'm talking about.
> https://github.com/openwrt/openwrt/pull/4192
> 
> So in short this backport lacks the dts changes and the pr4192 is mandatory or
> we will introduce perf regression in 21
> 

Thank you for pointing out the details of the DTS changes and CPU
performance.  Originally I was trying to achieve the smallest
backport, but in hindsight, it makes far more sense to avoid
frankensteining with partial changes.  I appreciate your patience and
advice!

Meanwhile, until PR #4192 can be reviewed/merged to master (so there's
commits to actually backport), I've thrown together a rough draft of
what changes would need backported:

https://github.com/openwrt/openwrt/compare/openwrt-21.02...digitalcircuit:openwrt-21.02-cpufreq-dtsivolt-cache
Cherry-pick of existing DTS changes and commits in PR #4192:
https://github.com/openwrt/openwrt/pull/4192
[NOTE: I might be missing commits!]

This isn't a real backport, it's just so I can try out these changes
right now.  So far, it builds and runs, and I've started the first
seven-hour SFTP backup test as described in FS#3099.

If there's anything I'm overlooking, or anything else I could try that
would be helpful, let me know!

No disrespect meant, either.  I realize the scope of these changes
means this might need to wait for 21.02.1, and meanwhile I'm happy to
continue making and testing custom builds.