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SubjectRe: [PATCH v3 0/8] NVIDIA Tegra clocksource driver improvements
31.05.2019 11:26, Peter De Schrijver пишет:
> On Fri, May 24, 2019 at 06:32:45PM +0300, Dmitry Osipenko wrote:
>> Hello,
>> This series primarily unifies the driver code across all Tegra SoC
>> generations. In a result the clocksources are allocated per-CPU on
>> older Tegra's and have a higher rating than the arch-timer, the newer
>> Tegra210 is getting support for microsecond clocksource and the driver's
>> code is getting much cleaner. Note that arch-timer usage is discouraged on
>> all Tegra's due to the time jitter caused by the CPU frequency scaling.
> I think the limitations are more as follows:
> Chip timer suffers cpu dvfs jitter can wakeup from cc7
> T20 us-timer No Yes
> T20 twd timer Yes No?
> T30 us-timer No Yes
> T30 twd timer Yes No?
> T114 us-timer No Yes
> T114 arch timer No Yes
> T124 us-timer No Yes
> T124 arch timer No Yes
> T210 us-timer No Yes
> T210 arch timer No No
> T210 clk_m timer No Yes
> right?

Doesn't arch timer run off the CPU clock? If yes (that's what I
assumed), then it should be affected by the DVFS. Otherwise I'll lower
the clocksource's rating for T114/124/132.

TWD can't wake CPU from the power-down state, so it's a solid "No" for
TWD in the "can wakeup from cc7" column.

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