Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20180515102715.GO29062@mai>
References: <cover.1526285602.git.baolin.wang@linaro.org> <20180515102715.GO29062@mai>
From:   Baolin Wang <baolin.wang@linaro.org>
Date:   Wed, 16 May 2018 10:20:17 +0800
Message-ID: <CAMz4kuJjhhty7HigPEA6Gm4HtFk_3t1aCwbX3c0mLLQF8SZBLw@mail.gmail.com>
Subject: Re: [RFC PATCH 00/10] Add persistent clock support
To:     Daniel Lezcano <daniel.lezcano@linaro.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        John Stultz <john.stultz@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Tony Lindgren <tony@atomide.com>, aaro.koskinen@iki.fi,
        linux@armlinux.org.uk, Mark Rutland <mark.rutland@arm.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Mark Brown <broonie@kernel.org>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        mlichvar@redhat.com, rdunlap@infradead.org,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jon Hunter <jonathanh@nvidia.com>,
        =?UTF-8?Q?Heiko_St=C3=BCbner?= <heiko@sntech.de>,
        Linus Walleij <linus.walleij@linaro.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Ingo Molnar <mingo@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, peterz@infradead.org,
        douly.fnst@cn.fujitsu.com, len.brown@intel.com,
        rajvi.jingar@intel.com,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        x86@kernel.org, Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-tegra@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        linux-omap@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Daniel,

On 15 May 2018 at 18:27, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
> On Mon, May 14, 2018 at 04:55:26PM +0800, Baolin Wang wrote:
>> Hi,
>>
>> We will meet below issues when compensating the suspend time for the timekeeping.
>>
>> 1. We have too many different ways of dealing with persistent timekeeping
>> across architectures, so it is hard for one driver to compatable with different
>> architectures.
>>
>> 2. On some platforms (such as Spreadtrum platform), we registered the high
>> resolution timer as one clocksource to update the OS time, but the high
>> resolution timer will be stopped in suspend state. So we use another one
>> always-on timer (but low resolution) to calculate the suspend time to
>> compensate the OS time. Though we can register the always-on timer as one
>> clocksource, we need re-calculate the mult/shift with one larger conversion
>> range to calculate the suspend time and need update the clock in case of
>> running over the always-on timer.
>
> First, can you elaborate what you mean by 'suspend state' ? On which power

What I mean is the high resolution timer will be stopped when the
system goes into suspend state.

> domain the clocksource belongs to?

On Spreadtrum platform, It belongs to one power domain named
"APCPU_TOP", that will be power down when the system goes into suspend
state.

-- 
Baolin.wang
Best Regards