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. > >> 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. Your initial response made it sound like you expected the MCT alone to be sufficient. Thanks, Mark. -- 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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