linux-kernel - Re: [PATCH v4 1/3] arm64: dts: qcom: sc7280: Add proxy interconnect requirements for modem

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Message-ID: <CAE-0n53hDDoetQW0Bz7noq4peuNCyrGsXaJdjFj=4sMkGeZFgw@mail.gmail.com>
Date:   Fri, 20 May 2022 12:07:20 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Sibi Sankar <quic_sibis@...cinc.com>
Cc:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        ohad@...ery.com, agross@...nel.org, mathieu.poirier@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        mka@...omium.org
Subject: Re: [PATCH v4 1/3] arm64: dts: qcom: sc7280: Add proxy interconnect
 requirements for modem

Quoting Sibi Sankar (2022-05-20 11:08:52)
> Hey Bjorn,
> Thanks for taking time to review the series.
>
> On 5/20/22 2:05 AM, Bjorn Andersson wrote:
> > On Thu 19 May 09:47 PDT 2022, Sibi Sankar wrote:
> >
> >> Add interconnects that are required to be proxy voted upon during modem
> >> bootup on SC7280 SoCs.
> >
> > This looks reasonable, but how come the vote is only for DDR frequency?
> > What about the buses between modem and ddr?
>
> The proxy votes that are put in aren't for perf related reasons, the
> modem was getting llcc timeouts while trying to read contents from
> memory. The hw team recommended the proxy votes as the fix.

Presumably the bootloader sets up some initial modem and ddr bus
bandwidth requests? Or the modem bootloader stage (MSA?) handles that
part?