From: kgene.kim@samsung.com (Kukjin Kim) Date: Wed, 25 Jun 2014 19:14:53 +0900 Subject: [PATCH v2] arm: exynos: Support cluster power off on exynos5420/5800 In-Reply-To: <7hy4wsvdsm.fsf@paris.lan> References: <1403104722-14848-1-git-send-email-a.kesavan@samsung.com> <1403181617-19743-1-git-send-email-a.kesavan@samsung.com> <7hy4wsvdsm.fsf@paris.lan> Message-ID: <01b501cf905e$4e95cf00$ebc16d00$@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Kevin Hilman wrote: > > Abhilash Kesavan writes: > Hi, > > Turning off a cluster when all 4 cores of the cluster are powered off > > saves power significantly. Powering off the A15 L2 alone gives around > > 100mW in savings. Add support for powering off the A15/A7 clusters on > > exynos5420/5800. > > > > The patch enables specific register bits which ensure that: > > - cluster L2 will be turned on before the first man is powered up. > > - last man will be turned off before the cluster L2 is turned off. > > - core is powered down before powering it up. > > > > Remove the exynos_cluster_power_control function completely as we can > > rely on the above mentioned bits rather than polling the cluster power > > status register. > > > > Signed-off-by: Abhilash Kesavan > > Acked-by: Nicolas Pitre > > --- > > Change in v2: > > Added a macro for the COMMON_OPTION register and used it in the MCPM > > back-end. > > > > The patch is based on Linux-next 20140619. It has been tested on an > > exynos5420-based chromebook using the "/dev/bL_switcher" interface as > > well as the script provided by Nicolas Pitre and Dave Martin [1]. > > > > Patch depends on: > > [v2] ARM: EXYNOS: mcpm: Don't rely on firmware's secondary_cpu_start > > > > [1] http://www.spinics.net/lists/linux-samsung-soc/msg31257.html > > Tested on exynos5800/Chromebook2 along with the dependency patch and using > the script from Dave and Nico. > > Tested-by: Kevin Hilman > Kevin, thanks for your test on the board ;-) Applied into samsung tree. Thanks, Kukjin