linux-kernel - Re: [PATCH 7/9] clocksource/drivers/rockchip

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Date:   Thu, 24 Nov 2016 16:05:55 +0300
From:   Alexander Kochetkov <al.kochet@...il.com>
To:     Heiko Stübner <heiko@...ech.de>
Cc:     daniel.lezcano@...aro.org, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH 7/9] clocksource/drivers/rockchip_timer: implement clocksource timer

Hello Heiko!

> 24 нояб. 2016 г., в 15:17, Heiko Stübner <heiko@...ech.de> написал(а):
> 
> In your dts-patch you reuse the rk3288-timer compatible value, which is also 
> non-ideal.

rockchip,rk-timer.txt states what I should use rockchip,rk3288-timer for rk3188 timers:

Required properties:
- compatible: shall be one of:
  "rockchip,rk3288-timer" - for rk3066, rk3036, rk3188, rk322x, rk3288, rk3368

Should I add "rockchip,rk3188-timer» (or better "rockchip,rk3036-timer») ? Or may be second
approach should be used?

> What you may want to do is introduce a rockchip,rk3188-timer compatible and 
> then make the timer-driver act accordingly, as you then know you are on a 
> rk3188-board ... see drivers attaching specific structs to the of_device_id 
> entries. From the documentation

May be it is better to prepend compatible string with "rockchip,rk3188-timer» in the dts
file only? elinux[1] recommend build compatible string from "exact device» string and
«other devices» that the device is compatible with.

As «other devices» string defined already, I use it.

[1] http://elinux.org/Device_Tree_Usage#Understanding_the_compatible_Property

	timer0: timer@...38000 {
		compatible = "rockchip,rk3188-timer", "rockchip,rk3288-timer»;
                …
	};

Just found what rk3036 already declared such way:

rk3036.dtsi:	timer: timer@...44000 {
rk3036.dtsi:		compatible = "rockchip,rk3036-timer", "rockchip,rk3288-timer»;

> 
> it also shouldn't really matter which timer 
> you use as clocksource, as on the rk3188 it seems all of them act the same way 
> (except timer3 being always on).

You are right.

I sent dts file with general timer settings, without clockevent enabled, so one could pick
up timer and setup it in the board dts (radxarock, for example) like:

&timer0 {
    rockchip,clocksource;
    status = «okay»;
};

> When touching devicetree-properties, please also adapt the binding document
> 	Documentation/devicetree/bindings/timer,rockchip,rk-timer.txt
> in this case and also include the devicetree maintainers.

If the patch[2] ok, I'll resend it and include devicetree maintainers.

[2] http://lists.infradead.org/pipermail/linux-rockchip/2016-November/013148.html

Regards,
Alexander.