lkml.org 
[lkml]   [2019]   [May]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 0/8] NVIDIA Tegra clocksource driver improvements
From
Date
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.

\
 
 \ /
  Last update: 2019-05-31 14:35    [W:0.164 / U:0.468 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site