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Wed, 03 Jun 2020 13:51:05 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 6C117C433CB; Wed, 3 Jun 2020 13:51:05 +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 CD2FEC433C6; Wed, 3 Jun 2020 13:51:04 +0000 (UTC) MIME-Version: 1.0 Date: Wed, 03 Jun 2020 19:21:04 +0530 From: Sai Prakash Ranjan To: Robin Murphy Subject: Re: [PATCH 2/2] coresight: tmc: Add shutdown callback for TMC ETR/ETF In-Reply-To: <68444180-3ebe-8988-493a-fdd1dff994b6@arm.com> References: <28123d1e19f235f97555ee36a5ed8b52d20cbdea.1590947174.git.saiprakash.ranjan@codeaurora.org> <20200601212858.GB24287@xps15> <1549935cf69ac3a006f32eb278821027@codeaurora.org> <6c1a4fbd-98cb-a49c-0ced-1318d5d5e7c8@arm.com> <7fe5762b5cb8f87e988232922d06c55d@codeaurora.org> <68444180-3ebe-8988-493a-fdd1dff994b6@arm.com> Message-ID: 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-20200603_065108_641991_2F64B549 X-CRM114-Status: GOOD ( 14.23 ) 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: Mathieu Poirier , Suzuki K Poulose , linux-arm-msm@vger.kernel.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org, Stephen Boyd , linux-arm-kernel@lists.infradead.org, Mike Leach 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 Hi Robin, On 2020-06-03 19:10, Robin Murphy wrote: > On 2020-06-03 13:26, Sai Prakash Ranjan wrote: >> Hi Robin, >> >> On 2020-06-03 17:51, Robin Murphy wrote: >>> On 2020-06-03 13:00, Sai Prakash Ranjan wrote: >>>> Hi Robin, Mathieu >>>> >>>> On 2020-06-03 17:07, Robin Murphy wrote: >>>>> On 2020-06-01 22:28, Mathieu Poirier wrote: >>>>>> That being said I'm sure that dependencies on an IOMMU isn't a >>>>>> problem confined >>>>>> to coresight. I am adding Robin Murphy, who added this commit [1], >>>>>> to the thread >>>>>> in the hope that he can provide guidance on the right way to do >>>>>> this. >>>>> >>>>> Right, it's not specific to CoreSight, and it's not even specific >>>>> to >>>>> IOMMUs really. In short, blame kexec ;) >>>>> >>>> >>>> Yes it is not specific to coresight, we are targeting this for all >>>> consumers/clients of SMMU(atleast on SC7180 SoC). We have display >>>> throwing >>>> NoC/interconnect errors[1] during reboot after SMMU is disabled. >>>> This is also not specific to kexec either as you explained here [2] >>>> about >>>> a case with display which is exacly what is happening in our system >>>> [1]. >>> >>> Sure, but those instances are begging the question of why the SMMU is >>> disabled at reboot in the first place ;) >>> >> >> That is what happens in SMMU shutdown callback right? It is the >> reboot/shutdown flow. > > Yes, that's where it happens, but my point is *why* it happens at all. > > hint: `git log --grep=shutdown drivers/iommu/` > Ah my change :) > If we could assume the system is always about to be powered off or > reset, we wouldn't need to do anything to the SMMU either ;) > Are you hinting at removing SMMU shutdown callback altogether ;) 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