From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Sender: sibis=codeaurora.org@mg.codeaurora.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 16 Mar 2020 22:07:04 +0530 From: Sibi Sankar Subject: Re: [PATCH 0/3] Request direct mapping for modem firmware subdevice In-Reply-To: <20200316155028.GB18704@infradead.org> References: <20200309182255.20142-1-sibis@codeaurora.org> <20200316155028.GB18704@infradead.org> Message-ID: <8cfddb6cbc424b131c9ab823c0c0f3f1@codeaurora.org> To: Christoph Hellwig Cc: bjorn.andersson@linaro.org, robh+dt@kernel.org, joro@8bytes.org, ohad@wizery.com, devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, agross@kernel.org, linux-arm-msm-owner@vger.kernel.org List-ID: Hey Christoph, Thanks for taking time to review the series. On 2020-03-16 21:20, Christoph Hellwig wrote: > On Mon, Mar 09, 2020 at 11:52:52PM +0530, Sibi Sankar wrote: >> The Q6 modem sub-system has direct access to DDR through memnoc and >> an indirect access routed through a SMMU which MSS CE (crypto engine >> sub-component of MSS) uses during out of reset sequence. Request >> direct >> mapping for the modem-firmware subdevice since smmu is not expected >> to provide access control/translation for these SIDs (sandboxing of >> the >> modem is achieved through XPUs engaged using SMC calls). > > Please fix your device tree so that the device isn't bound to an > IOMMU. the bindings proposed in the series would add a sub-device with an iommu property. modem_pil: remoteproc@xxxxx { ... modem-firmware { iommus = <&apps_smmu 0x460 0x1>; }; ... }; Remoteproc device will not have a iommu property but modem-firmware sub-device will. With ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT y, we would want to configure the SID either in direct mapping or bypass (either will do since protection is achieved through other means) https://lore.kernel.org/lkml/497e40b8-300f-1b83-4312-93a58c459d1d@arm.com/ Currently the restructuring is trending towards whats discussed in the ^^ thread. i.e either direct mapping/bypass will be done in the SoC specific corner of the SMMU driver. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.