From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Philippe Brucker Subject: Re: [PATCH 3/8] iommu/arm-smmu-v3: Support platform SSID Date: Wed, 19 Jun 2019 12:53:46 +0100 Message-ID: <73cfb797-5ae7-b9d9-01ea-fe98a1bed5c3@arm.com> References: <20190610184714.6786-1-jean-philippe.brucker@arm.com> <20190610184714.6786-4-jean-philippe.brucker@arm.com> <20190618180851.GK4270@fuggles.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190618180851.GK4270@fuggles.cambridge.arm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: "joro@8bytes.org" , "robh+dt@kernel.org" , Mark Rutland , Robin Murphy , "jacob.jun.pan@linux.intel.com" , "iommu@lists.linux-foundation.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "eric.auger@redhat.com" List-Id: devicetree@vger.kernel.org On 18/06/2019 19:08, Will Deacon wrote: >> + /* >> + * If the SMMU doesn't support 2-stage CD, limit the linear >> + * tables to a reasonable number of contexts, let's say >> + * 64kB / sizeof(ctx_desc) = 1024 = 2^10 >> + */ >> + if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB)) >> + master->ssid_bits = min(master->ssid_bits, 10U); > > Please introduce a #define for the 10, so that it is computed in the way > you describe in the comment (a bit like we do for things like queue sizes). Ok >> + >> group = iommu_group_get_for_dev(dev); >> if (!IS_ERR(group)) { >> iommu_group_put(group); >> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c >> index f04a6df65eb8..04f4f6b95d82 100644 >> --- a/drivers/iommu/of_iommu.c >> +++ b/drivers/iommu/of_iommu.c >> @@ -206,8 +206,12 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, >> if (err) >> break; >> } >> - } >> >> + fwspec = dev_iommu_fwspec_get(dev); >> + if (!err && fwspec) >> + of_property_read_u32(master_np, "pasid-num-bits", >> + &fwspec->num_pasid_bits); >> + } > > Hmm. Do you know if there's anything in ACPI for this? Yes, IORT version D introduced a "substream width" field for the Named component node (platform device). I don't think it existed last time I checked, so I'll see about supporting it. Thanks, Jean