linux-kernel - Re: [PATCH 3/4] arm64: dts: Add mediatek MT8173 SoC and evaluation board dts and Makefile

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Date:	Thu, 11 Dec 2014 14:02:53 +0100
From:	Matthias Brugger <matthias.bgg@...il.com>
To:	Eddie Huang <eddie.huang@...iatek.com>
Cc:	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Rob Herring <robh+dt@...nel.org>,
	Jason Cooper <jason@...edaemon.net>,
	srv_heupstream <srv_heupstream@...iatek.com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Olof Johansson <olof@...om.net>,
	Robert Richter <rrichter@...ium.com>,
	Mark Brown <broonie@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	YH Chen (陳昱豪) <yh.chen@...iatek.com>
Subject: Re: [PATCH 3/4] arm64: dts: Add mediatek MT8173 SoC and evaluation
 board dts and Makefile

Hi Eddie,

2014-12-11 13:47 GMT+01:00 Eddie Huang <eddie.huang@...iatek.com>:
> On Wed, 2014-12-10 at 15:50 +0100, Matthias Brugger wrote:
>> 2014-12-10 15:27 GMT+01:00 Yingjoe Chen <yingjoe.chen@...iatek.com>:
>> >
>> > Hi,
>> >
>> > On Wed, 2014-12-10 at 18:50 +0800, Eddie Huang wrote:
>> > <...>
>> >> diff --git a/arch/arm64/boot/dts/mt8173-evb.dts b/arch/arm64/boot/dts/mt8173-evb.dts
>> >> new file mode 100644
>> >> index 0000000..adf26dd
>> >> --- /dev/null
>> >> +++ b/arch/arm64/boot/dts/mt8173-evb.dts
>> > <...>
>> >> +     timer {
>> >> +             compatible = "arm,armv8-timer";
>> >> +             interrupt-parent = <&gic>;
>> >> +             interrupts = <1 13 0x8>,
>> >> +                          <1 14 0x8>,
>> >> +                          <1 11 0x8>,
>> >> +                          <1 10 0x8>;
>> >> +             clock-frequency = <13000000>;
>> >
>> > I believe our firmware doesn't need this line. Please remove it.
>>
>> The point here would be to know if you need to enable a special timer
>> from the mtk-timer block to get the arch timer working.
>> In any case, you will need some sort of timer. This dts does not
>> describe the mtk-timer (may in the mt8173 it does not exist) but
>> defines the clocks clk26m and clk32k. So if you don't use the
>> mtk-timer, please remove the clocks as there isn't a block using them.
>>
>
> MT8173 has two timer set: CPUGPT and APBGPT, and use CPUGPT to enable
> arch_timer. Previous series only have APBGPT. MT8173 still need enable
> CPUGPT to get arch timer working, we put this in loader, and transparent
> to kernel. So I will remove clk26m and clk32k in next version.

Ok, so if this is done in the bootloader, there shouldn't be a problem
then. Perfect.

Just one more comment on the dts nodes. Can you use the makros defined
for the interrupt type
e.g "GIC_PPI 14 IRQ_TYPE_LEVEL_LOW" instead of "1 14 0x8". This makes
the dts easier to read.

Thanks,
Matthias

>



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