Re: CPUIdle for Exynos5422 Odroid-XU3/XU4 boards.

[Krzysztof Kozlowski <k.kozlowski@samsung.com>]

W dniu 28.08.2015 o 17:35, Javier Martinez Canillas pisze:
> Hello Bartlomiej and Lorenzo,
> 
> Thanks a lot for your explanations.
> 
> On 08/27/2015 06:58 PM, Bartlomiej Zolnierkiewicz wrote:
>
>> If somebody wants to implement a separate Exynos542x/Exynos5800
>> big.LITTLE cpuidle driver for them I see no problem with it and I'm
>> willing to help in maintaining it.
>>
> 
> Ok, I'll see if I can take a look what is needed to implement a Exynos542x CPUidle
> driver. I'm quite busy with other stuff right now but I should be less busy in a
> couple of weeks.

The only useful users of Exynos542x cpuidle would be Chromebooks.
Probably the same goes with suspend to RAM. Non-mobile devices could
leave without it.

In the same time cpuidle and S2R would require a significant amount of
work. Testing would have to be performed on Chromebooks. I have doubts
it would work on Odroid XU3.

I dug into S2R issues on Odroid XU3 and after fixing trivial imprecise
abort I don't have clue. It just dies somewhere in firmware/bootloader.
Vendor code has a lot more stuff related to suspend and testing it
one-by-one whether it fixes the issue is frustrating.

Do we really need cpuidle or S2R on Exynos542x/5800?

> 
> Maybe is a little bit out of topic but since Anand also asked about CPUFreq support,
> are you planning on re-posting your "cpufreq: add generic cpufreq driver support
> for Exynos5250/5800 platforms" [0] series?

That would be useful. Bartlomiej, do you have plans for continuing the work?

Best regards,
Krzysztof