From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH] arm64: tegra: Fix CPU compatible string for Tegra132 Date: Thu, 26 May 2016 10:29:12 -0600 Message-ID: <57472458.1010802@wwwdotorg.org> References: <20160523074221.7135-1-josephl@nvidia.com> <574509E7.4030208@nvidia.com> <5745C7E4.2050908@wwwdotorg.org> <5746C1F1.6070703@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5746C1F1.6070703-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Joseph Lo Cc: Thierry Reding , Alexandre Courbot , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Catalin Marinas , Will Deacon , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On 05/26/2016 03:29 AM, Joseph Lo wrote: > On 05/25/2016 11:42 PM, Stephen Warren wrote: >> On 05/24/2016 08:11 PM, Joseph Lo wrote: >>> On 05/23/2016 03:42 PM, Joseph Lo wrote: >>>> As per commit f634da375fc96 ("Documentation: DT bindings: add nvidia, >>>> tegra132-denver compatible string"), fixing the CPU compatible string >>>> for >>>> Tegra132 to match the binding document currently. >>>> >>>> Signed-off-by: Joseph Lo >>>> --- >>>> arch/arm64/boot/dts/nvidia/tegra132.dtsi | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/arch/arm64/boot/dts/nvidia/tegra132.dtsi >>>> b/arch/arm64/boot/dts/nvidia/tegra132.dtsi >>>> index 2013f8916084..7b1cdc029de3 100644 >>>> --- a/arch/arm64/boot/dts/nvidia/tegra132.dtsi >>>> +++ b/arch/arm64/boot/dts/nvidia/tegra132.dtsi >>>> @@ -964,13 +964,13 @@ >>>> >>>> cpu@0 { >>>> device_type = "cpu"; >>>> - compatible = "nvidia,denver", "arm,armv8"; >>>> + compatible = "nvidia,tegra132-denver", "arm,armv8"; >>> >>> Hi Stephen, Thierry, >>> >>> Should we fix this or fix the compatible string in the binding document >>> as just "nvidia,denver" to represent all the Devner CPU revisions just >>> like some other CPUs did? e.g. arm,cortex-a57, which represents all the >>> A57 revisions. >> >> I would expect compatible to be: >> >> compatible = "nvidia,tegra132-denver", "nvidia,denver", "arm,armv8"; > > Because we don't have "nvidia,denver" binding in the document, to do > what you said, supposely I should add that first and fix the binding for > Tegra132, right? Yes. >> The "nvidia,denver" entry is already present, and hence probably >> shouldn't be removed. It can represent "Denver 1.0". We should add the >> T132 entry to indicate the specific implementation. Admittedly right now >> there's a 1:1 relation between SoC and Denver version. Either/both of >> those could in theory be required to trigger specific bug-fixes/WARs. >> >> For later chips which have a different Denver version, I'd expect to see >> something like: >> >> compatible = "nvidia,tegraNNN-denver", "nvidia,denverMMM", "arm,armv8"; >> >> ... where NNN is the SoC version/name and MMM is the Denver version. >> There could be extra entries in the property if the new versions are >> backwards-compatible with old versions. > > Because it's 1:1 relationship, if we have new cores coming later, we > should add both of the compatible string of SoC version and CPU core > version in the ARM CPU binding document, is that correct? Yes. I suspect that on some future SoCs, it won't be a 1:1 relation; we'll re-use a Denver version across multiple SoCs, just like we do with some ARM CPU models, but we'll see.