linux-kernel - Re: [PATCH] arm64: dts: qcom: sm8350: fix BAM DMA crash and reboot

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Message-ID: <7b909a56-1b3d-79fb-0286-b10117982dc3@linaro.org>
Date:   Mon, 26 Jun 2023 14:46:20 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Luca Weiss <luca.weiss@...rphone.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bhupesh Sharma <bhupesh.sharma@...aro.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: Re: [PATCH] arm64: dts: qcom: sm8350: fix BAM DMA crash and reboot

On 26/06/2023 13:32, Luca Weiss wrote:
> Hi Krzysztof,
> 
> On Wed Jun 21, 2023 at 4:36 PM CEST, Krzysztof Kozlowski wrote:
>> SM8350 HDK and MTP boards were silently dying and rebooting during BAM
>> DMA probe:
>>
>>   [    1.574304] vreg_bob: Setting 3008000-3960000uV
>>   [    1.576918] bam-dFormat: Log Type - Time(microsec) - Message -
>>   Optional Info
>>   Log Type: B - Since Boot(Power On Reset),  D - Delta,  S - Statistic
>>   S - QC_IMAGE_VERSION_STRING=BOOT.MXF.1.0-00637.1-LAHAINA-1
>>   S - IMAGE_VARIANT_STRING=SocLahainaLAA
>>   S - OEM_IMAGE_VERSION_STRING=crm-ubuntu77
>>   S - Boot Interface: UFS
>>
>> It seems that BAM DMA is locally controller (not by firmware) and
>> requires proper initialization by the driver prior to use, at least on
>> HDK8350 and MTP8350, but probably on all boards.
> 
> Are you sure that the bam (and subsequent the qce) actually probes with
> this change? From reading the code I don't see how the bam should probe
> without either qcom,controlled-remotely or qcom,powered-remotely but no

Why the binding does not require either this or that? Eh, buggy stuff...


> clocks supplied. I think the probe just fails with this change, right?

I will need to double check. I was happy enough to be able to boot my
device instead of having crashes, but indeed it would be nice to fix it
fully.


Best regards,
Krzysztof