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Date:   Fri, 16 Dec 2022 01:01:18 +0000
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Alex Elder <elder@linaro.org>
Cc:     robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        andersson@kernel.org, konrad.dybcio@linaro.org, agross@kernel.org,
        quic_sibis@quicinc.com, elder@kernel.org,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arm64: dts: qcom: sc7280: enable IPA in
 sc7280-herobrine-lte-sku.dtsi
Message-ID: <Y5vDXm4oo2cn3etX@google.com>
References: <20221215224552.1232449-1-elder@linaro.org>
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On Thu, Dec 15, 2022 at 04:45:52PM -0600, Alex Elder wrote:

> Subject: arm64: dts: qcom: sc7280: enable IPA in sc7280-herobrine-lte-sku.dtsi

nit: that sounds as if IPA wasn't enabled previously. It would be
clearer to say something like: "sc7280: only enable IPA for boards
with a modem".

> IPA is only needed on a platform if it includes a modem, and not all
> SC7280 SoC variants do.  The file "sc7280-herobrine-lte-sku.dtsi" is
> used to encapsulate definitions related to Chrome OS SC7280 devices
> where a modem is present, and that's the proper place for the IPA
> node to be enabled.
> 
> Currently IPA is enabled in "sc7280-idp.dtsi", which is included by
> DTS files for Qualcomm reference platforms (all of which include the
> modem).  That also includes "sc7280-herobrine-lte-sku.dtsi", so
> enabling IPA there would make it unnecessary for "sc7280-idp.dtsi"
> to enable it.
> 
> The only other place IPA is enabled is "sc7280-qcard.dtsi".
> That file is included only by "sc7280-herobrine.dtsi", which
> is (eventually) included only by these top-level DTS files:
>   sc7280-herobrine-crd.dts
>   sc7280-herobrine-herobrine-r1.dts
>   sc7280-herobrine-evoker.dts
>   sc7280-herobrine-evoker-lte.dts
>   sc7280-herobrine-villager-r0.dts
>   sc7280-herobrine-villager-r1.dts
>   sc7280-herobrine-villager-r1-lte.dts
> All of but two of these include "sc7280-herobrine-lte-sku.dtsi", and
> for those cases, enabling IPA there means there is no need for it to
> be enabled in "sc7280-qcard.dtsi".
> 
> The two remaining cases will no longer enable IPA as a result of
> this change:
>   sc7280-herobrine-evoker.dts
>   sc7280-herobrine-villager-r1.dts
> Both of these have "lte" counterparts, and are meant to represent
> board variants that do *not* have a modem.
> 
> This is exactly the desired configuration.
> 
> Signed-off-by: Alex Elder <elder@linaro.org>
> Reviewed-by: Sibi Sankar <quic_sibis@quicinc.com>
> Tested-by: Sibi Sankar <quic_sibis@quicinc.com>

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>