From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Poirier Subject: Re: [PATCH 1/3] arm64: dts: qcom: sdm845: Add Coresight support Date: Mon, 14 Jan 2019 08:35:09 -0700 Message-ID: <20190114153509.GA29374@xps15> References: <20190111184643.GA22691@xps15> <81172d85ed7782e0db561fcf96a82d46@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <81172d85ed7782e0db561fcf96a82d46@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: saiprakash.ranjan@codeaurora.org Cc: Rob Herring , Suzuki K Poulose , Leo Yan , Alexander Shishkin , Andy Gross , David Brown , devicetree@vger.kernel.org, Mark Rutland , Rajendra Nayak , Vivek Gautam , Sibi Sankar , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-msm-owner@vger.kernel.org List-Id: devicetree@vger.kernel.org On Sat, Jan 12, 2019 at 06:21:00PM +0530, saiprakash.ranjan@codeaurora.org wrote: > Hi Mathieu, > > > > + > > > + etm@7040000 { > > > + compatible = "arm,coresight-etm4x", "arm,primecell"; > > > + arm,primecell-periphid = <0x000bb95d>; > > > > I'm a little curious as to why you need to bypass the normal AMBA bus > > discovery > > method by forcing the peripheral ID. Tracers don't show up the way > > other > > coresight devices do at boot time? > > > > Yes on some Qcom SoC's like SDM845 and also on some previous ones, for > ETM(only) amba bus discovery method fails because of wrong pid read from the > registers. So we have to force this primecell peripheral ids to probe etm. Ok, if that is the case please add a comment to explain the situation. Otherwise someone will assuredly ask again in the future. Mathieu > > - Sai > > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of > Code Aurora Forum, hosted by The Linux Foundation