From: Andre Przywara <andre.przywara@arm.com>
To: samuel@sholland.org, Maxime Ripard <maxime.ripard@bootlin.com>,
Icenowy Zheng <icenowy@aosc.io>
Cc: Chen-Yu Tsai <wens@csie.org>,
Linus Walleij <linus.walleij@linaro.org>,
linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
linux-sunxi@googlegroups.com
Subject: Re: [linux-sunxi] Re: [PATCH v3 6/7] arm64: allwinner: h6: add the basical Allwinner H6 DTSI file
Date: Wed, 28 Feb 2018 11:08:07 +0000 [thread overview]
Message-ID: <4c9cb1c9-922b-655e-cf31-c09b5b20d829@arm.com> (raw)
In-Reply-To: <b9bc5944-b9e3-91d7-8012-c87a2b2d17fa@sholland.org>
Hi,
On 26/02/18 15:54, Samuel Holland wrote:
> On 02/26/18 03:26, Maxime Ripard wrote:
>> On Fri, Feb 23, 2018 at 11:22:06PM +0800, Icenowy Zheng wrote:
>>>>> + psci {
>>>>> + compatible = "arm,psci-0.2";
>>>>> + method = "smc";
>>>>> + };
>>>>
>>>> Is it needed? The bootloader should fill it with whatever version it
>>>> has, shouldn't it?
>>>
>>> But we now use ATF rather than U-Boot PSCI. U-Boot will not fill ATF
>>> info.
>>>
>>> See A64/H5 device trees.
>>
>> So if the PSCI version implemented in ATF ever changes, we would have
>> to update all the DT everywhere, but only if you're running the new
>> version?
>
> Yes but no. PSCI 1.0 is generally backward compatible with PSCI 0.2. In fact,
> the Linux driver treats them exactly the same:
>
> { .compatible = "arm,psci-0.2", .data = psci_0_2_init},
> { .compatible = "arm,psci-1.0", .data = psci_0_2_init},
Yeah, it's actually unclear why we have that new compatible name in the
first place, since starting with PSCI v0.2 the version can be perfectly
read using the mandatory PSCI_VERSION call. And DT aims to only cover
things that are not discoverable.
> For the H6, however, the oldest ATF source available (which I believe was the
> one in use during bringup) is based on mainline 1.4, and is already at PSCI
> version 1.1:
>
> [ 0.000000] psci: probing for conduit method from DT.
> [ 0.000000] psci: PSCIv1.1 detected in firmware.
> [ 0.000000] psci: Using standard PSCI v0.2 function IDs
> [ 0.000000] psci: MIGRATE_INFO_TYPE not supported.
>
> So we could go ahead and bump the compatible to "arm,psci-1.0".
I'd rather leave it at "arm,psci-0.2", since this improves compatibility
to other OSes or DT users.
Cheers,
Andre.
next prev parent reply other threads:[~2018-02-28 11:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-23 12:35 [PATCH v3 5/7] clk: sunxi-ng: add support for the Allwinner H6 CCU Icenowy Zheng
2018-02-23 12:35 ` [PATCH v3 6/7] arm64: allwinner: h6: add the basical Allwinner H6 DTSI file Icenowy Zheng
2018-02-23 15:20 ` Maxime Ripard
2018-02-23 15:22 ` Icenowy Zheng
2018-02-26 9:26 ` Maxime Ripard
2018-02-26 15:54 ` Samuel Holland
2018-02-28 11:08 ` Andre Przywara [this message]
2018-02-23 12:35 ` [PATCH v3 7/7] arm64: allwinner: h6: add support for Pine H64 board Icenowy Zheng
2018-03-01 9:29 ` [PATCH v3 5/7] clk: sunxi-ng: add support for the Allwinner H6 CCU Maxime Ripard
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