On 01/15/2015 10:34 PM, Mark Rutland wrote: > On Thu, Jan 15, 2015 at 12:52:38PM +0000, Chanwoo Choi wrote: >> 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 > > Hmm. That is annoying. Your boot code should have been initialising this > already. Right, I want to resolve the issue for Exynos3250 but I don't have any information. Maybe this issue should be fixed by the architector of Exynos SoC or any samsung developer who can contact the information of ARCH timer. > >>>> 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. > > I'm not opposed to the MCT. My only concern is that a configured and > enabled architected timer is mandated by the boot protocol, and is a > prerequisite for a functioning kernel. Thanks for your opinion. As I replyed on previous mail, I agree that ARCH timer is necessary. Your initial response made it > sound like you expected the MCT alone to be sufficient. I didn't mean it. 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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