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Date:   Wed, 24 Nov 2021 17:17:38 +0530
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Subject: Re: [PATCH 1/4] dt-bindings: arm: qcom: Document qcom,sc7280-crd
 board
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To:     Matthias Kaehlcke <mka@chromium.org>
Cc:     agross@kernel.org, bjorn.andersson@linaro.org, robh+dt@kernel.org,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, sboyd@codeaurora.org,
        dianders@chromium.org, kgodara@codeaurora.org
References: <1637650813-16654-1-git-send-email-rnayak@codeaurora.org>
 <1637650813-16654-2-git-send-email-rnayak@codeaurora.org>
 <YZ0AZQDB6VPUAt8s@google.com>
From:   Rajendra Nayak <rnayak@codeaurora.org>
In-Reply-To: <YZ0AZQDB6VPUAt8s@google.com>
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On 11/23/2021 8:23 PM, Matthias Kaehlcke wrote:
> On Tue, Nov 23, 2021 at 12:30:10PM +0530, Rajendra Nayak wrote:
>> Document the qcom,sc7280-crd board based off sc7280 SoC,
>> The board is also known as hoglin in the Chrome OS builds,
>> and given there would be multiple (at least one more) rev
>> of this board document the google,hoglin-rev0 compatible as well.
>>
>> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
>> ---
>>   Documentation/devicetree/bindings/arm/qcom.yaml | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/qcom.yaml b/Documentation/devicetree/bindings/arm/qcom.yaml
>> index c8808e0..2abfd28 100644
>> --- a/Documentation/devicetree/bindings/arm/qcom.yaml
>> +++ b/Documentation/devicetree/bindings/arm/qcom.yaml
>> @@ -203,6 +203,8 @@ properties:
>>             - enum:
>>                 - qcom,sc7280-idp
>>                 - qcom,sc7280-idp2
>> +              - qcom,sc7280-crd
>> +              - google,hoglin-rev0
> 
> I think we also want the generic 'google,hoglin' compatible string, analogous to
> for example 'google,lazor' and 'google,lazor-revN'. For lazor there are no
> explicit compatible entries for rev3 and above, there were no DT relevant
> hardware changes for rev > 3, hence the 'google,lazor' compatible string is
> used, without the need to modify the DT for each new HW revision.
> 
> Also on my CRD the bootloader thinks it is running on a rev4:
> 
>    Compat preference: google,hoglin-rev4 google,hoglin
> 
> The board still boots thanks to the 'google,hoglin' entry in my device tree,
> but it seems you need to add more revN entries, or start with rev4 if you
> don't really care about supporting older revisions. In the later case you
> coul only have 'google,hoglin' for now, and add 'rev4' when you add support
> for the next revision (supposing it has DT relevant hardware changes). The
> sc7180-trogdor boards can serve as an example on how to deal with board
> revisions.

Sure, i think i will perhaps go with just the google,hoglin compatible
for now and add revs as and when needed, the fact that these boards have
a few initial revs not used at all seem to make it really confusing

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