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Date:   Tue, 13 Dec 2022 22:43:56 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     andersson@kernel.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, bp@alien8.de,
        tony.luck@intel.com, quic_saipraka@quicinc.com,
        konrad.dybcio@linaro.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, james.morse@arm.com,
        mchehab@kernel.org, rric@kernel.org, linux-edac@vger.kernel.org,
        quic_ppareek@quicinc.com, luca.weiss@fairphone.com,
        stable@vger.kernel.org
Subject: Re: [PATCH v2 03/13] arm64: dts: qcom: sdm845: Fix the base
 addresses of LLCC banks
Message-ID: <20221213171356.GD4862@thinkpad>
References: <20221212123311.146261-1-manivannan.sadhasivam@linaro.org>
 <20221212123311.146261-4-manivannan.sadhasivam@linaro.org>
 <038e6569-9f8f-3b59-0243-af6dcf0c2d80@linaro.org>
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On Tue, Dec 13, 2022 at 05:27:45PM +0100, Krzysztof Kozlowski wrote:
> On 12/12/2022 13:33, Manivannan Sadhasivam wrote:
> > The LLCC block has several banks each with a different base address
> > and holes in between. So it is not a correct approach to cover these
> > banks with a single offset/size. Instead, the individual bank's base
> > address needs to be specified in devicetree with the exact size.
> > 
> > Also, let's get rid of reg-names property as it is not needed anymore.
> > The driver is expected to parse the reg field based on index to get the
> > addresses of each LLCC banks.
> > 
> > Cc: <stable@vger.kernel.org> # 5.4
> 
> No, you cannot backport it. You will break users.
> 

If the driver change gets backported, it will break users, isn't it?

> > Fixes: ba0411ddd133 ("arm64: dts: sdm845: Add device node for Last level cache controller")
> > Reported-by: Parikshit Pareek <quic_ppareek@quicinc.com>
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> >  arch/arm64/boot/dts/qcom/sdm845.dtsi | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > index 65032b94b46d..683b861e060d 100644
> > --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > @@ -2132,8 +2132,9 @@ uart15: serial@a9c000 {
> >  
> >  		llcc: system-cache-controller@1100000 {
> >  			compatible = "qcom,sdm845-llcc";
> > -			reg = <0 0x01100000 0 0x31000>, <0 0x01300000 0 0x50000>;
> > -			reg-names = "llcc_base", "llcc_broadcast_base";
> 
> Once property was made required, you cannot remove it. What if other
> bindings user depends on it?
> 
> Please instead keep/update the reg-names and/or mark it as deprecated.
> It must stay in DTS for some time.
> 

Fair enough. I will mark it as deprecated in binding and will keep it in dts.

Thanks,
Mani

> Best regards,
> Krzysztof
> 

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