On 26/04/16 20:35, Grygorii Strashko wrote: > On 04/26/2016 07:02 PM, Liviu Dudau wrote: >> On Tue, Apr 26, 2016 at 06:28:52PM +0300, Grygorii Strashko wrote: >> >> Hi Grygorii, >> >> First time I'm seeing this patch, so I have a few questions, mostly >> related to the commit message: > > Hm. You are in cc for RFC. > Sry, forgot to add link [1]. > >> >>> This patch intended to fix following cases: >>> - SoC-A has ARM GT, defines DT node for ARM GT and selects >>> ARM_GLOBAL_TIMER statically in Kconfig file. SoC-B has ARM GT and >>> defines DT node for ARM GT, but do not selects ARM_GLOBAL_TIMER >>> statically in Kconfig file. In case of multiplatform build ARM GT will >>> be implicitly enabled for SoC-B. >> >> Well, SoC-B has the GT *and* the DT node, so what is the problem with >> enabling it for SoC-B? If there are reasons not to use the Global Timer >> on SoC-B, surely a better option would be to mark it in DT with status = "disabled"; > > This was rejected [2]. DT describes HW and if it is functional the status = "disabled" > is not good choice. > ARM GT can't be used as clocksource/sched_clock/clockevent when CPUFreq or > CPUIdle are enabled :(, and this is Linux specific functionality and > not HW description. It sounds to me like the cleanest option might then be to address it within the Linux-specific driver itself. How feasible would it be for the GT driver to detect at runtime whether CPUfreq/idle will be used and simply refuse to register as a clocksource if so? (I guess there are probably horrible initialisation order issues, at least...) Robin. >> >>> >>> - There is no way to disable ARM GT without modifying Kconfig file, >>> once ARM_GLOBAL_TIMER is selected statically in Kconfig file. >> >> What about disabling the DT node? >> >> Not sure I properly understand the problem you are trying to solve here. > > I'd like to have way to enable/disable ARM GT without modifying Kernel sources > (Kconfig specifically) which is now impossible. > >> >>> >>> Hence, fix above case by defining both HAVE_ARM_GLOBAL_TIMER and >>> ARM_GLOBAL_TIMER as recommended by 'Adding common features and make >>> the usage configurable' section in kconfig-language.txt. All places in >>> ARM folder where ARM_GLOBAL_TIMER was used now replaced on >>> HAVE_ARM_GLOBAL_TIMER. >> >> I'm OK with the way you have changed ARM_GLOBAL_TIMER from a sticky config >> option to a selectable one, but I would like more details on the problem >> this was causing you. >> > > The same HW (board) could be used with PM features enabled (power saving) > and disabled (-RT). Without this change it will require to have > and maintain two branches, but with it - just separate defconfig. > > [1] http://lists.infradead.org/pipermail/linux-rockchip/2016-February/007159.html > [2] http://www.spinics.net/lists/devicetree/msg102918.html > >> >>> >>> Cc: Daniel Lezcano <daniel.lezcano at linaro.org> >>> Cc: Florian Fainelli <f.fainelli at gmail.com> >>> Cc: Russell King <linux at arm.linux.org.uk> >>> Cc: Wei Xu <xuwei5 at hisilicon.com> >>> Cc: Shawn Guo <shawnguo at kernel.org> >>> Cc: Sascha Hauer <kernel at pengutronix.de> >>> Cc: Srinivas Kandagatla <srinivas.kandagatla at gmail.com> >>> Cc: Maxime Coquelin <maxime.coquelin at st.com> >>> Cc: Masahiro Yamada <yamada.masahiro at socionext.com> >>> Cc: Liviu Dudau <liviu.dudau at arm.com> >>> Cc: Sudeep Holla <sudeep.holla at arm.com> >>> Cc: Jun Nie <jun.nie at linaro.org> >>> Cc: Michal Simek <michal.simek at xilinx.com> >>> Cc: Jesper Nilsson <jesper.nilsson at axis.com> >>> Cc: Lars Persson <lars.persson at axis.com> >>> Cc: Mike Looijmans <mike.looijmans at topic.nl> >>> Acked-by: S?ren Brinkmann <soren.brinkmann at xilinx.com> >>> Acked-by: Moritz Fischer <moritz.fischer at ettus.com> >>> Signed-off-by: Grygorii Strashko <grygorii.strashko at ti.com> >>> --- >>> Changes is v1: >>> - updated mach-artpec >>> - rebased on top of tip: timers/core >>> commit: 86d3473 time: Introduce do_sys_settimeofday64() >>> >>> arch/arm/mach-artpec/Kconfig | 2 +- >>> arch/arm/mach-bcm/Kconfig | 4 ++-- >>> arch/arm/mach-hisi/Kconfig | 2 +- >>> arch/arm/mach-imx/Kconfig | 2 +- >>> arch/arm/mach-rockchip/Kconfig | 2 +- >>> arch/arm/mach-sti/Kconfig | 2 +- >>> arch/arm/mach-uniphier/Kconfig | 2 +- >>> arch/arm/mach-vexpress/Kconfig | 2 +- >>> arch/arm/mach-zx/Kconfig | 2 +- >>> arch/arm/mach-zynq/Kconfig | 2 +- >>> drivers/clocksource/Kconfig | 7 ++++++- >>> 11 files changed, 17 insertions(+), 12 deletions(-) >>> >>> diff --git a/arch/arm/mach-artpec/Kconfig b/arch/arm/mach-artpec/Kconfig >>> index 6cbe5a2..6cbca77 100644 >>> --- a/arch/arm/mach-artpec/Kconfig >>> +++ b/arch/arm/mach-artpec/Kconfig >>> @@ -9,7 +9,7 @@ config MACH_ARTPEC6 >>> depends on ARCH_MULTI_V7 >>> select ARM_AMBA >>> select ARM_GIC >>> - select ARM_GLOBAL_TIMER > > [...] >
