Re: [PATCH v5 3/8] ARM: dts: rockchip: add timer entries to rk3188 SoC

From: Alexander Kochetkov <al.kochet@gmail.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Heiko Stuebner <heiko@sntech.de>,
	LKML <linux-kernel@vger.kernel.org>,
	devicetree@vger.kernel.org,
	LAK <linux-arm-kernel@lists.infradead.org>,
	linux-rockchip@lists.infradead.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Rob Herring <robh+dt@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Caesar Wang <wxt@rock-chips.com>,
	Huang Tao <huangtao@rock-chips.com>
Subject: Re: [PATCH v5 3/8] ARM: dts: rockchip: add timer entries to rk3188 SoC
Date: Mon, 30 Jan 2017 16:13:07 +0300	[thread overview]
Message-ID: <046978C2-808F-4EC3-9429-063BC1A7CE7B@gmail.com> (raw)
In-Reply-To: <20170130120444.GE2206@mai>

> 30 янв. 2017 г., в 15:04, Daniel Lezcano <daniel.lezcano@linaro.org> написал(а):
> 
> There is no case when the rockchip timer is used for the clockevent.
The is already timer entry for rk3228 in the DT. And it act as clockevent. I guess it work as backup,
but I cannot test it also. In order to not break DT compatibility I had to provide one timer to be
initialized as clockevent. And implemented implicit rule the driver (first DT timer - clockevent,
second DT timer - clocksource) already exists for other timers.

> If I'm not wrong, you can check /proc/interrupts and see there is no interrupt
> on the rockchip timer.

Yes, you right here. I’ve temporary disable smp_twd to test rockchip timer interrupts.
There is no interrupt on the rockchip timer during normal work.

> - when the CPU enters a deep idle state. But such state does not exist on rk3188
ARM chip/revision specific?

> - when the system goes to suspend. But the timers are stopped in any case and
>   CPU0 is always on.
There is timer for rk3228 in the DT. I guess there are situations where it can be used.
May be the situations are also acceptable for rk3188? May be something like suspend to RAM or
suspend to HDD? I am not expert in that questions. I can do some tests if you give hint/link.

So, as I understood you suggest to leave only one timer what can be used as clocksource
only. I can implement that, but there should be DT rule what allow to setup timer
as clocksource only. I cannot do more without timer framework support.
Looks, like I have to wait your patch to implement that.

Alexander.