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Message-ID: <20190531082634.GA6070@pdeschrijver-desktop.Nvidia.com>
Date: Fri, 31 May 2019 11:26:34 +0300
From: Peter De Schrijver <pdeschrijver@...dia.com>
To: Dmitry Osipenko <digetx@...il.com>
CC: Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Joseph Lo <josephl@...dia.com>,
Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Nicolas Chauvet <kwizart@...il.com>
Subject: Re: [PATCH v3 0/8] NVIDIA Tegra clocksource driver improvements
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?
Peter.
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