linux-kernel - Re: [PATCH] ARM64: dts: rockchip: add core dtsi file for RK3399 SoCs

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Message-ID: <571E0D1B.9080909@rock-chips.com>
Date:	Mon, 25 Apr 2016 20:27:07 +0800
From:	"Huang, Tao" <huangtao@...k-chips.com>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Marc Zyngier <marc.zyngier@....com>, devicetree@...r.kernel.org,
	davidriley@...omium.org, heiko@...ech.de, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, catalin.marinas@....com,
	will.deacon@....com, dianders@...omium.org, smbarber@...omium.org,
	linux-rockchip@...ts.infradead.org, robh+dt@...nel.org,
	galak@...eaurora.org, jwerner@...omium.org,
	linux-kernel@...r.kernel.org, Jianqun Xu <jay.xu@...k-chips.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] ARM64: dts: rockchip: add core dtsi file for RK3399 SoCs

Hi, Mark:
On 2016年04月25日 18:47, Mark Rutland wrote:
> On Mon, Apr 25, 2016 at 06:19:28PM +0800, Huang, Tao wrote:
>> Hi, Mark:
>> On 2016年04月25日 18:05, Mark Rutland wrote:
>>> On Mon, Apr 25, 2016 at 05:48:51PM +0800, Huang, Tao wrote:
>>>> and pmu define as:
>>>>     pmu_a53 {
>>>>         compatible = "arm,cortex-a53-pmu";
>>>>         interrupts = <GIC_PPI 7 IRQ_TYPE_LEVEL_LOW &part0>;
>>>>         interrupt-affinity = <&cpu_l0>,
>>>>                      <&cpu_l1>,
>>>>                      <&cpu_l2>,
>>>>                      <&cpu_l3>;
>>>>     };
>>>>
>>>>     pmu_a72 {
>>>>         compatible = "arm,cortex-a72-pmu", "arm,cortex-a57-pmu";
>>> That Cortex-A57 PMU fallback should just go. We already have Cortex-A72
>>> PMU support upstream, and I believe there are sufficient differences
>>> such that the Cortex-A72 PMU is not a strict superset of the Cortex-A57
>>> PMU.
>> As I say, I tested on v4.4, I don't back port
>> arch/arm64/kernel/perf_event.c, so I use "arm,cortex-a57-pmu". Upstream
>> will use "arm,cortex-a72-pmu" only.
>> BTW, I don't see any differences between A72/A57 in source code:
> The PMU name is exposed to userspace, so the user will be told they have
> a Cortex-A57 PMU, with all of the IMPLEMENTATION DEFINED events that
> implies.
>
> We don't handle those IMPLEMENTATION DEFINED events in the kernel, but
> for the sake of the userspace ABI, we should not expose the Cortex-A72
> PMU as a Cortex-A57 PMU.
>
> Given the code is otherwise identical, it should be relatively simple to
> backport the A72 support.
>
Understood, thank you!

Huang, Tao