linux-kernel - [PATCH v1 2/2] iommu/tegra-smmu: Revert workaround that was needed for Nyan Big Chromebook

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Message-Id: <20210328233256.20494-2-digetx@gmail.com>
Date:   Mon, 29 Mar 2021 02:32:56 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Joerg Roedel <joro@...tes.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Reddy <vdumpa@...dia.com>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Will Deacon <will@...nel.org>
Cc:     iommu@...ts.linux-foundation.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 2/2] iommu/tegra-smmu: Revert workaround that was needed for Nyan Big Chromebook

The previous commit fixes problem where display client was attaching too
early to IOMMU during kernel boot in a multi-platform kernel configuration
which enables CONFIG_ARM_DMA_USE_IOMMU=y. The workaround that helped to
defer the IOMMU attachment for Nyan Big Chromebook isn't needed anymore,
revert it.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/iommu/tegra-smmu.c | 71 +-------------------------------------
 1 file changed, 1 insertion(+), 70 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index af1e4b5adb27..572a4544ae88 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -869,69 +869,10 @@ static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
 	return SMMU_PFN_PHYS(pfn) + SMMU_OFFSET_IN_PAGE(iova);
 }
 
-static struct tegra_smmu *tegra_smmu_find(struct device_node *np)
-{
-	struct platform_device *pdev;
-	struct tegra_mc *mc;
-
-	pdev = of_find_device_by_node(np);
-	if (!pdev)
-		return NULL;
-
-	mc = platform_get_drvdata(pdev);
-	if (!mc)
-		return NULL;
-
-	return mc->smmu;
-}
-
-static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev,
-				struct of_phandle_args *args)
-{
-	const struct iommu_ops *ops = smmu->iommu.ops;
-	int err;
-
-	err = iommu_fwspec_init(dev, &dev->of_node->fwnode, ops);
-	if (err < 0) {
-		dev_err(dev, "failed to initialize fwspec: %d\n", err);
-		return err;
-	}
-
-	err = ops->of_xlate(dev, args);
-	if (err < 0) {
-		dev_err(dev, "failed to parse SW group ID: %d\n", err);
-		iommu_fwspec_free(dev);
-		return err;
-	}
-
-	return 0;
-}
-
 static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
 {
-	struct device_node *np = dev->of_node;
-	struct tegra_smmu *smmu = NULL;
-	struct of_phandle_args args;
-	unsigned int index = 0;
-	int err;
-
-	while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
-					  &args) == 0) {
-		smmu = tegra_smmu_find(args.np);
-		if (smmu) {
-			err = tegra_smmu_configure(smmu, dev, &args);
-
-			if (err < 0) {
-				of_node_put(args.np);
-				return ERR_PTR(err);
-			}
-		}
-
-		of_node_put(args.np);
-		index++;
-	}
+	struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
 
-	smmu = dev_iommu_priv_get(dev);
 	if (!smmu)
 		return ERR_PTR(-ENODEV);
 
@@ -1158,16 +1099,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 	if (!smmu)
 		return ERR_PTR(-ENOMEM);
 
-	/*
-	 * This is a bit of a hack. Ideally we'd want to simply return this
-	 * value. However the IOMMU registration process will attempt to add
-	 * all devices to the IOMMU when bus_set_iommu() is called. In order
-	 * not to rely on global variables to track the IOMMU instance, we
-	 * set it here so that it can be looked up from the .probe_device()
-	 * callback via the IOMMU device's .drvdata field.
-	 */
-	mc->smmu = smmu;
-
 	size = BITS_TO_LONGS(soc->num_asids) * sizeof(long);
 
 	smmu->asids = devm_kzalloc(dev, size, GFP_KERNEL);
-- 
2.30.2