On Thu, Jan 15, 2015 at 9:46 PM, Chanwoo Choi <cwchoi00@xxxxxxxxx> wrote: > Hi Mark, > > On Thu, Jan 15, 2015 at 8:29 PM, Mark Rutland <mark.rutland@xxxxxxx> wrote: >> On Wed, Jan 14, 2015 at 11:57:00PM +0000, Chanwoo Choi wrote: >>> Hi Kukjin, >>> >>> On 01/15/2015 01:02 AM, Daniel Lezcano wrote: >>> > On 01/14/2015 04:51 PM, Kukjin Kim wrote: >>> >> On 01/14/15 14:33, Chanwoo Choi wrote: >>> >> >>> >> Hi, >>> >> >>> >> + Doug, Olof >>> >> >>> >>> This patch adds the support for Exynos 64bit SoC. The delay_timer is only used >>> >>> for Exynos 32bit SoC. >>> >>> >>> >> Yes, the Exynos MCT(Multi-Core Timer) is 64bit timer and it is available >>> >> on 64bit exynos SoC such as exynos7. But basically ARMv8 architecture is >>> >> including ARM ARCH timer (ARM Generic Timer) and exynos7 also has >>> >> implemented it and additionally its access is faster than using memory >>> >> mapped register called SFR for MCT...so Doug submitted patch to use MCT >>> >> on 32bit exynos SoCs before. >>> >>> I know arch_timer. As you comment, ARCH timer would be used for system timer for ARMv8. >>> But, Exynos5433/Exynos7 (ARMv8) include MCT (Multi-Core Timer) IP. I checked it on >>> Exynos5433/EXynos7 User-manaual and tested it. >>> >>> I think that exynos_mct.c should support the Exynos 64-bit SoC >>> because Exynos5433/Exynos7 include already MCT (Multi-Core Timer) IP. >>> >>> Also, I have a problem to verify ARCH timer on Exynos SoC. Exynos User-manual never includes >>> the detailed information about for ARCH timer(e.g, clock for ARCH timer). I knew that >>> I can get the document of ARCH timer for ARM official site but I think it is insufficient >>> to implement ARCH timer on Exynos SoC. >> >> What do you mean by "insufficient to implement ARCH timer"? > > As I knew, timer must need the source clock. The clock for ARCH timer > has dependency on Exynos SoC, But I cannot find I'm so sorry about this mistake. I pressed the send button before completing reply. As I knew, timer must need the source clock. The clock for ARCH timer has dependency on Exynos SoC, But I cannot find the clock information for ARCH timer on Exynos SoC user-manual. When I tried to use ARCH timer on Exynos3250, It is not working. We can check this ARCH timer issue of Exynos3250 on following patch[1]: [1] http://www.spinics.net/lists/arm-kernel/msg322943.html > >> >> The architected timer is mandatory in ARMv8, and required by the arm64 >> kernel. >> >> Additional timers may be requried if you want to put all CPUs into low >> power states where the timer logic may be disabled and/or lose state, >> but regardless the architected timers are necessary. I agree that ARCH timer is mandatory. I just think that existing exynos-mct.c driver should support the Exynos5/7 SoC because released Exynos5/7 SoC includes already MCT IP for system timer. Best Regards, Chanwoo Choi -- 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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