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.
