From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Subject: Re: CPUIdle for Exynos5422 Odroid-XU3/XU4 boards. Date: Fri, 28 Aug 2015 14:50:32 +0200 Message-ID: <2001174.gNo7Q8ZTrR@amdc1976> References: <55E01D61.8020706@osg.samsung.com> <55E0573B.4060604@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit Return-path: In-reply-to: <55E0573B.4060604@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org To: Krzysztof Kozlowski Cc: Javier Martinez Canillas , Lorenzo Pieralisi , Anand Moon , Daniel Lezcano , Kukjin Kim , "linux-samsung-soc@vger.kernel.org" , Przemyslaw Marczak , Kevin Hilman , "linux-pm@vger.kernel.org" List-Id: linux-pm@vger.kernel.org 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