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Date: Tue, 07 Apr 2020 15:16:35 +0530 From: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org> To: Mike Leach <mike.leach@...aro.org> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>, Suzuki K Poulose <suzuki.poulose@....com>, Leo Yan <leo.yan@...aro.org>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Stephen Boyd <swboyd@...omium.org>, linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org Subject: Re: [RFC PATCH] coresight: dynamic-replicator: Fix handling of multiple connections Hi Mike, Thanks for taking a look. On 2020-04-06 16:25, Mike Leach wrote: > Hi, > > The programmable replicator hardware by design enables trace through > both ports on reset. (see 1, section 4.4, 9.11) The replicator driver > overrides this functionality to disable output, until the Coresight > infrastructure chooses a path from source to sink. > Now given that the hardware design is such that we must be able to > allow trace to be sent to both ports, a generic patch to prevent this > does not seem appropriate here. > > I think this needs further investigation - to determine why this > appears to be failing in this particular instance. > Yes, this probably needs further investigation, but CPU hardlock stack trace doesnt help much. I could always trigger this hard lockup without this patch on SC7180 SoC and this is only seen when ETR is used as the sink. The only difference I could see between non working case (on SC7180 [1]) and the working case (on SDM845 [2]) is the path from source to sink. SC7180 source to sink path(Not working): ---------------------------------------- etm0_out | apss_funnel_in0 | apss_merge_funnel_in | funnel1_in4 | merge_funnel_in1 | swao_funnel_in | etf_in | swao_replicator_in | replicator_in | etr_in SDM845 source to sink path(Working): ------------------------------------ etm0_out | apss_funnel_in0 | apss_merge_funnel_in | funnel2_in5 | merge_funnel_in2 | etf_in | replicator_in | etr_in [1] - https://lore.kernel.org/patchwork/patch/1212946/ [2] - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/qcom/sdm845.dtsi?h=v5.6#n1910 Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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