Messages in this thread | | | Subject | Re: [PATCH V5 2/7] clocksource: tegra: add Tegra210 timer support | From | Joseph Lo <> | Date | Sun, 3 Feb 2019 00:07:09 +0800 |
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On 2/2/19 9:38 PM, Dmitry Osipenko wrote: > 02.02.2019 2:53, Joseph Lo пишет: >> On 2/2/19 2:08 AM, Dmitry Osipenko wrote: >>> 01.02.2019 18:37, Joseph Lo пишет: >>>> On 2/1/19 11:13 PM, Dmitry Osipenko wrote: >>>>> 01.02.2019 17:13, Joseph Lo пишет: >>>>>> On 2/1/19 9:54 PM, Jon Hunter wrote: >>>>>>> >>>>>>> On 01/02/2019 13:11, Dmitry Osipenko wrote: >>>>>>>> 01.02.2019 16:06, Dmitry Osipenko пишет: >>>>>>>>> 01.02.2019 6:36, Joseph Lo пишет: >>>>>>>>>> Add support for the Tegra210 timer that runs at oscillator clock >>>>>>>>>> (TMR10-TMR13). We need these timers to work as clock event device and to >>>>>>>>>> replace the ARMv8 architected timer due to it can't survive across the >>>>>>>>>> power cycle of the CPU core or CPUPORESET signal. So it can't be a wake-up >>>>>>>>>> source when CPU suspends in power down state. >>>>>>>>>> >>>>>>>>>> Also convert the original driver to use timer-of API. >>>>>>>>>> >>>>>>>>>> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> >>>>>>>>>> Cc: Thomas Gleixner <tglx@linutronix.de> >>>>>>>>>> Cc: linux-kernel@vger.kernel.org >>>>>>>>>> Signed-off-by: Joseph Lo <josephl@nvidia.com> >>>>>>>>>> Acked-by: Thierry Reding <treding@nvidia.com> >>>>>>>>>> --- >>>> snip. >>>>>>>>>> +} >>>>>>>>>> +TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra210_timer_init); >>>>>>>>>> +#else /* CONFIG_ARM */ >>>>>>>>>> +static int __init tegra20_init_timer(struct device_node *np) >>>>>>>>>> +{ >>>>>>>>> What about T132? Isn't it ARM64 which uses tegra20-timer IP? At least T132 DT suggests so and seems this change will break it. >>>>>>>>> >>>>>>>>> [snip] >>>>>>>>> >>>>>>>> >>>>>>>> Ah, noticed the "depends on ARM" in Kconfig.. Seems okay then. >>>>>>>> >>>>>>> >>>>>>> >>>>>>> This is a good point, because even though we had 'depends on ARM', this >>>>>>> still means that the Tegra132 DT is incorrect. >>>>>>> >>>>>>> Joseph, can you take a quick look at Tegra132? >>>>>> >>>>>> Hi Jon and Dmitry, >>>>>> >>>>>> No worry about T132, T132 uses arch timer (v7). The tegra20 timer driver has never been used. We should fix the dtsi file later. >>>>> >>>>> Hi Joseph, >>>>> >>>>> So is T132 HW actually incompatible with the tegra20-timer? If it's compatible, then I think the driver's code should be made more universal to support T132. >>>>> >>>> >>>> From HW point of view, the TIMER1 ~ TIMER4 is compatible with "nvidia,tegra20-timer". But Tegra132 actually has 10 timers which are exactly the same as Tegra30. So it should backward compatible with "nvidia,tegra30-timer", which is tegra_wdt driver now. And Tegra132 should never use this driver. >>>> >>>> The Tegra timer driver should only be used on Tegra20/30/210, three platforms only. Others use arch timer driver for system timer driver. >>>> >>>> So we don't really need to take care the usage on other Tegra platforms. >>> >>> Doesn't Linux kernel put in use all of available timers? If yes, then we probably would want to expose all available timers. It looks to me that right now tegra20-timer exposes only a single-shared timer to the system [please correct me if I'm wrong]. Wouldn't make sense at least to give a timer per CPU core? >>> >> >> No, only one timer driver works at a time. ( see /proc/timer_list to check which timer is working.) > > Okay, thanks for the clarification. > >>> It looks to me that right now tegra20-timer exposes only a single-shared timer to the system [please correct me if I'm wrong]. Wouldn't make sense at least to give a timer per CPU core? >> >> Yes, it's correct. the timer-tegra20 only provides a single-shared timer. And yes, ,it should provide a timer per CPU core. But that is another task, this patch only introduce the timer support for Tegra210. Others that originally from timer-tegra20 driver still remain the same. > > I may take a look at it. Could be better for older Tegra's to use tegra20-timer for the per-CPU timer since TWD timer has some time-jitter due to DVFS. >
That would be great, thank you. Joseph
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