Re: [PATCH] arm64: tegra: Fix CPU compatible string for Tegra132

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

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 <josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> ---
>>   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";

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.