Hi, On Friday, May 30, 2014 01:34:45 PM Tomasz Figa wrote: > Hi Daniel, > > On 30.05.2014 11:30, Daniel Lezcano wrote: > > On 04/24/2014 07:42 PM, Tomasz Figa wrote: > >> Hi Daniel, > >> > >> Please see my comments inline. > >> > >> Btw. Please fix your e-mail composer to properly wrap your messages > >> around 7xth column, as otherwise they're hard to read. > >> > >> On 04.04.2014 11:48, Daniel Lezcano wrote: > >>> The following driver is for exynos4210. I did not yet finished the > >>> other boards, so > >>> I created a specific driver for 4210 which could be merged later. > >>> > >>> The driver is based on Colin Cross's driver found at: > >>> > >>> https://android.googlesource.com/kernel/exynos/+/e686b1ec67423c40b4fdf811f9a4dfa3b393a010%5E%5E!/ > >>> > >>> > >>> > >>> This one was based on a 3.4 kernel and an old API. > >>> > >>> It has been refreshed, simplified and based on the recent code cleanup > >>> I sent > >>> today. > >>> > >>> The AFTR could be entered when all the cpus (except cpu0) are down. In > >>> order to > >>> reach this situation, the couple idle states are used. > >>> > >>> There is a sync barrier at the entry and the exit of the low power > >>> function. So > >>> all cpus will enter and exit the function at the same time. > >>> > >>> At this point, CPU0 knows the other cpu will power down itself. CPU0 > >>> waits for > >>> the CPU1 to be powered down and then initiate the AFTR power down > >>> sequence. > >>> > >>> No interrupts are handled by CPU1, this is why we switch to the timer > >>> broadcast > >>> even if the local timer is not impacted by the idle state. > >>> > >>> When CPU0 wakes up, it powers up CPU1 and waits for it to boot. Then > >>> they both > >>> exit the idle function. > >>> > >>> This driver allows the exynos4210 to have the same power consumption > >>> at idle > >>> time than the one when we have to unplug CPU1 in order to let CPU0 to > >>> reach > >>> the AFTR state. > >>> > >>> This patch is a RFC because, we have to find a way to remove the macros > >>> definitions and cpu powerdown function without pulling the arch > >>> dependent > >>> headers. > >>> > >>> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> > >>> --- > >>> arch/arm/mach-exynos/common.c | 11 +- > >>> drivers/cpuidle/Kconfig.arm | 8 ++ > >>> drivers/cpuidle/Makefile | 1 + > >>> drivers/cpuidle/cpuidle-exynos4210.c | 226 > >>> ++++++++++++++++++++++++++++++++++ > > > > [ ... ] > > > > > >> Otherwise, I quite like the whole idea. I need to play a bit with CPU > >> hotplug and PMU to verify that things couldn't really be simplified a > >> bit, but in general this looks reasonably. > > > > Hi Tomasz, > > > > did you have time to look at this simplification ? > > Unfortunately I got preempted with other things to do and now I'm on > vacation. I worked a bit with Bart (added on CC) on this and generally > the conclusion was that all the things are necessary. He was also > working to extend the driver to support Exynos4x12. > > Bart, has anything interesting showed up since we talked about this last > time? Since we last looked into this I have fixed the "standard" AFTR support for Exynos3250 and started to work on adding Exynos3250 support to this driver (as Exynos3250 support has bigger priority than Exynos4x12 one). Unfortunately I also got preempted with other things so it is still unfinished and doesn't work yet. Moreover I had no possibility to test the new driver on Exynos4210 based Origen yet (I hope to do this next week). Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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