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From:   Dmitry Osipenko <digetx@gmail.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Mikko Perttunen <cyndis@kapsi.fi>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Joerg Roedel <joro@8bytes.org>,
        Nicolas Chauvet <kwizart@gmail.com>
Cc:     devicetree@vger.kernel.org, nouveau@lists.freedesktop.org,
        iommu@lists.linux-foundation.org, dri-devel@lists.freedesktop.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH v1 2/6] of/device: Don't back devices DMA with IOMMU if that's undesired by driver
Date:   Fri, 27 Jul 2018 02:16:20 +0300
Message-Id: <20180726231624.21084-3-digetx@gmail.com>
In-Reply-To: <20180726231624.21084-1-digetx@gmail.com>
References: <20180726231624.21084-1-digetx@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Respect device driver requirement for device DMA not to be implicitly
backed with IOMMU by skipping the backing setup for drivers that do not
want that.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/of/device.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 33d85511d790..e70b7a886875 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -163,6 +163,13 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 	dev_dbg(dev, "device is%sbehind an iommu\n",
 		iommu ? " " : " not ");
 
+	/*
+	 * Respect device driver requirement for device DMA not to be
+	 * implicitly backed with IOMMU.
+	 */
+	if (iommu && dev->driver->no_implicit_iommu)
+		iommu = NULL;
+
 	arch_setup_dma_ops(dev, dma_addr, size, iommu, coherent);
 
 	return 0;
-- 
2.18.0