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

[Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>]

Hi,

On Friday, August 28, 2015 09:42:35 PM Krzysztof Kozlowski wrote:
> 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?

Yes.  It is still on my TODO but may take a while (1-2 weeks) before
I find some time to actually do it.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics