Messages in this thread | | | Subject | Re: [PATCH 1/2] clocksource/drivers/exynos_mct: Prioritise Arm arch timer on arm64 | From | Daniel Lezcano <> | Date | Mon, 21 Jun 2021 12:24:44 +0200 |
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On 21/06/2021 12:17, Marek Szyprowski wrote:
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>>>>>> I'm not sure that exynos mct is working without problem >>>>>> such as the case of 6282edb72bed. >>>>>> As described on On ,6282edb72bed the arch timer on exynos SoC >>>>>> depends on Exynos MCT device. the arch timer is not able to work >>>>>> without Exynos MCT because of using the common module. >>>>> Is it possible to change the DT to have a phandle to the exynos_mct, so >>>>> it will be probed before the arch_arm_timer ? >>>> I think that DT changes is not proper way to keep the order between >>>> exynos_mct and arch timer. >>> exynos4_mct_frc_start() is called unconditionally from probe via >>> exynos4_clocksource_init() so as long as the mct probes first, then the >>> arch timer should work, no? The rating shouldn't affect that. >> How do you ensure the exynos mct is probed before the arch timer ? >> >> The Makefile provides the right order, but the dependency is implicit. > > In my test systems based on Exynos5433, the bootloader enabled MCT, so > kernel can also start with arch_timer then switch to MCT. The probe > order also depend on the order of DT nodes, so with the current dts MCT > is probed first. This is not the best approach, but so far it works.
Right, generally assuming the firmware is doing the right thing from an initialization POV is not a good idea :/
But in our case, as pointed by Will, the cpuhotplug ordering gives the right sequence. So it should be fine.
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