linux-kernel - Re: [PATCH v2 4/4] arm64: dts: qcom: sc7280: Add cpu and llcc BWMON (=> interconnect issue)

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Message-ID: <754f8193-09ec-8bbf-e0d4-898525dc242f@linaro.org>
Date:   Tue, 17 Jan 2023 18:33:41 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Rajendra Nayak <quic_rjendra@...cinc.com>,
        Georgi Djakov <djakov@...nel.org>, agross@...nel.org,
        andersson@...nel.org, konrad.dybcio@...ainline.org,
        robh+dt@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org, Douglas Anderson <dianders@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>
Subject: Re: [PATCH v2 4/4] arm64: dts: qcom: sc7280: Add cpu and llcc BWMON
 (=> interconnect issue)

On 17/01/2023 18:27, Matthias Kaehlcke wrote:
> 
>>> which would set the initially bandwidths to 0 and determine the actually
>>> needed bandwidth. But since the driver isn't probed the initial
>>> bandwidths stay at INT_MAX.
>>>
>>> This isn't actually an issue with this patch, but how the interconnect
>>> framework deals with devices that are registered on the bus, but aren't
>>> probed (yet). Not sure how this would be best fixed. Georgi, do you have
>>> any ideas?
>>
>> Why the device is not probed (yet)? If it is registered, it will come
>> soon during boot up.
> 
> Because CONFIG_QCOM_ICC_BWMON is not enabled for the board in question (see
> above). It could be enabled as a short term mitigtion, however we shouldn't
> require drivers to be enabled just because the DT has a corresponding node.

It's the same case as with all other interconnect leafs/consumers. The
same behavior if you do not have it enabled, right? If not, I wonder
what is here different?

Best regards,
Krzysztof