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Tue, 28 Apr 2020 12:23:17 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id A17AEC433F2; Tue, 28 Apr 2020 12:23:17 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id 1F6D1C433D2; Tue, 28 Apr 2020 12:23:17 +0000 (UTC) MIME-Version: 1.0 Date: Tue, 28 Apr 2020 17:53:17 +0530 From: Sai Prakash Ranjan To: Suzuki K Poulose , mike.leach@linaro.org Subject: Re: [PATCH] coresight: dynamic-replicator: Fix handling of multiple connections In-Reply-To: <84918e7d-c933-3fa1-a61e-0615d4b3cf2c@arm.com> References: <20200426143725.18116-1-saiprakash.ranjan@codeaurora.org> <84918e7d-c933-3fa1-a61e-0615d4b3cf2c@arm.com> Message-ID: <668ea1283a6dd6b34e701972f6f71034@codeaurora.org> X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200428_052321_684875_8ED85E94 X-CRM114-Status: GOOD ( 16.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, mathieu.poirier@linaro.org, swboyd@chromium.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-04-27 19:23, Suzuki K Poulose wrote: > On 04/27/2020 10:45 AM, Mike Leach wrote: [...] >>> >>> This is not sufficient. You must prevent another session trying to >>> enable the other port of the replicator as this could silently fail >>> the "on-going" session. Not ideal. Fail the attempt to enable a port >>> if the other port is active. You could track this in software and >>> fail early. >>> >>> Suzuki >> >> While I have no issue in principle with not enabling a path to a sink >> that is not in use - indeed in some cases attaching to unused sinks >> can cause back-pressure that slows throughput (cf TPIU) - I am >> concerned that this modification is masking an underlying issue with >> the platform in question. >> >> Should we decide to enable the diversion of different IDs to different >> sinks or allow different sessions go to different sinks, then this has >> potential to fail on the SC7180 SoC - and it will be difficult in >> future to associate a problem with this discussion. > > Mike, > > I think thats a good point. > Sai, please could we narrow down this to the real problem and may be > work around it for the "device" ? Do we know which sink is causing the > back pressure ? We could then push the "work around" to the replicator > it is connected to. > > Suzuki Hi Suzuki, Mike, To add some more to the information provided earlier, swao_replicator(6b06000) and etf are in AOSS (Always-On-SubSystem) group. Also TPIU(connected to qdss_replicator) and EUD(connected to swao_replicator) sinks are unused. Please ignore the id filter values provided earlier. Here are ID filter values after boot and before enabling replicator. As per these idfilter values, we should not try to enable replicator if its already enabled (in this case for swao_replicator) right? localhost ~ # cat /sys/bus/amba/devices/6b06000.replicator/replicator1/mgmt/idfilter0 0x0 localhost ~ # cat /sys/bus/amba/devices/6b06000.replicator/replicator1/mgmt/idfilter1 0x0 localhost ~ # cat /sys/bus/amba/devices/6046000.replicator/replicator0/mgmt/idfilter0 0xff localhost ~ # cat /sys/bus/amba/devices/6046000.replicator/replicator0/mgmt/idfilter1 0xff I think the unused sink EUD(also in AOSS group) probably is causing the backpressure here. Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel