On 31/05/2019 14:33, Dmitry Osipenko wrote:
> 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.

Wouldn't make sense to rename the timer-tegra20.c to timer-tegra.c now ?


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