From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail27.static.mailgun.info ([104.130.122.27]:64710 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387831AbgCLG2s (ORCPT ); Thu, 12 Mar 2020 02:28:48 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 12 Mar 2020 11:58:30 +0530 From: Sai Prakash Ranjan Subject: Re: [PATCH 0/3] Request direct mapping for modem firmware subdevice In-Reply-To: References: <20200309182255.20142-1-sibis@codeaurora.org> <20200310112332.GG3794@8bytes.org> <4ed6ddd667a3e6f670084a443d141474@codeaurora.org> <20200310162320.GL3794@8bytes.org> Message-ID: Sender: linux-remoteproc-owner@vger.kernel.org To: Robin Murphy Cc: Joerg Roedel , Sibi Sankar , ohad@wizery.com, devicetree@vger.kernel.org, linux-kernel-owner@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn.andersson@linaro.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, agross@kernel.org, saiprakash.ranjan@codeaurora.org List-ID: Hi Robin, On 2020-03-10 22:14, Robin Murphy wrote: > On 10/03/2020 4:23 pm, Joerg Roedel wrote: >> On Tue, Mar 10, 2020 at 07:30:50PM +0530, Sibi Sankar wrote: >>> The accesses are initiated by the firmware >>> and they access modem reserved regions. >>> However as explained in ^^ any accesses >>> outside the region will result in a violation >>> and is controlled through XPUs (protection units). >> >> Okay, this sounds like a case for arm_smmu_get_resv_region(). It >> should >> return an entry for the reserved memory region the firmware needs to >> access, so that generic iommu can setup this mapping. >> >> Note that it should return that entry only for your device, not for >> all >> devices. Maybe there is a property in DT or IORT you can set to >> transport this information into the arm-smmu driver. >> >> This is pretty similar to RMRR mapping on the Intel VT-d IOMMU or >> Unity-mapped ranges in the AMD-Vi IOMMU. > > Yup, a way to describe boot-time memory regions in IORT is in the > process of being specced out; the first attempt at an equivalent for > DT is here: > > https://lore.kernel.org/linux-iommu/20191209150748.2471814-1-thierry.reding@gmail.com/ > > If that's not enough and the SMMU still needs to treat certain Stream > IDs specially because they may be untranslatable (due to having direct > access to memory as a side-channel), then that should be handled in > the SoC-specific corner of the SMMU driver, not delegated to > individual endpoint drivers. > Are you talking about this one for SoC specific change - https://lore.kernel.org/patchwork/patch/1183530/ Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation