linux-kernel - Re: [PATCH V10 7/7] arm64: dts: qcom: sa8775p: Add CPU OPP tables to scale DDR/L3

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Message-ID: <xyqax25jrm3hsairpv7ovqe6zkzaab757zq44o4dgcnsdco3go@ktsgnry6h6za>
Date: Wed, 26 Mar 2025 19:42:24 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Raviteja Laggyshetty <quic_rlaggysh@...cinc.com>
Cc: Georgi Djakov <djakov@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Odelu Kukatla <quic_okukatla@...cinc.com>,
        Mike Tipton <quic_mdtipton@...cinc.com>,
        Jagadeesh Kona <quic_jkona@...cinc.com>,
        Jeff Johnson <jeff.johnson@....qualcomm.com>,
        Sibi Sankar <quic_sibis@...cinc.com>, linux-arm-msm@...r.kernel.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Shivnandan Kumar <quic_kshivnan@...cinc.com>
Subject: Re: [PATCH V10 7/7] arm64: dts: qcom: sa8775p: Add CPU OPP tables to
 scale DDR/L3

On Mon, Mar 24, 2025 at 06:32:03PM +0000, Raviteja Laggyshetty wrote:
> From: Jagadeesh Kona <quic_jkona@...cinc.com>
> 
> Add OPP tables required to scale DDR and L3 per freq-domain
> on SA8775P platform.
> 
> If a single OPP table is used for both CPU domains, then
> _allocate_opp_table() won't be invoked for CPU4 but instead
> CPU4 will be added as device under the CPU0 OPP table. Due
> to this, dev_pm_opp_of_find_icc_paths() won't be invoked for
> CPU4 device and hence CPU4 won't be able to independently scale
> it's interconnects. Both CPU0 and CPU4 devices will scale the
> same ICC path which can lead to one device overwriting the BW
> vote placed by other device. Hence CPU0 and CPU4 require separate
> OPP tables to allow independent scaling of DDR and L3 frequencies
> for each CPU domain, with the final DDR and L3 frequencies being
> an aggregate of both.
> 
> Co-developed-by: Shivnandan Kumar <quic_kshivnan@...cinc.com>
> Signed-off-by: Shivnandan Kumar <quic_kshivnan@...cinc.com>
> Signed-off-by: Raviteja Laggyshetty <quic_rlaggysh@...cinc.com>
> Signed-off-by: Jagadeesh Kona <quic_jkona@...cinc.com>
> ---
>  arch/arm64/boot/dts/qcom/sa8775p.dtsi | 210 ++++++++++++++++++++++++++
>  1 file changed, 210 insertions(+)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>

-- 
With best wishes
Dmitry