122 lines
4.0 KiB
Diff
122 lines
4.0 KiB
Diff
From 723288836628bc1c0855f3bb7b64b1803e4b9e4a Mon Sep 17 00:00:00 2001
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From: Robin Murphy <robin.murphy@arm.com>
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Date: Thu, 31 Aug 2017 11:32:54 +0100
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Subject: of: restrict DMA configuration
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Moving DMA configuration to happen later at driver probe time had the
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unnoticed side-effect that we now perform DMA configuration for *every*
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device represented in DT, rather than only those explicitly created by
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the of_platform and PCI code.
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As Christoph points out, this is not really the best thing to do. Whilst
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there may well be other DMA-capable buses that can benefit from having
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their children automatically configured after the bridge has probed,
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there are also plenty of others like USB, MDIO, etc. that definitely do
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not support DMA and should not be indiscriminately processed.
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The good news is that in most cases the DT "dma-ranges" property serves
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as an appropriate indicator - per a strict interpretation of the spec,
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anything lacking a "dma-ranges" property should be considered not to
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have a mapping of DMA address space from its children to its parent,
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thus anything for which of_dma_get_range() does not succeed does not
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need DMA configuration. Certain bus types have a general expectation of
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DMA capability and carry a well-established precedent that an absent
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"dma-ranges" implies the same as the empty property, so we automatically
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opt those in to DMA configuration regardless, to avoid regressing most
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existing platforms.
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Fixes: 09515ef5ddad ("of/acpi: Configure dma operations at probe time for platform/amba/pci bus devices")
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Reported-by: Christoph Hellwig <hch@lst.de>
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Signed-off-by: Robin Murphy <robin.murphy@arm.com>
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Acked-by: Rob Herring <robh@kernel.org>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
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---
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drivers/of/device.c | 48 ++++++++++++++++++++++++++++++++----------------
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1 file changed, 32 insertions(+), 16 deletions(-)
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diff --git a/drivers/of/device.c b/drivers/of/device.c
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index e0a28ea..04c4c95 100644
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--- a/drivers/of/device.c
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+++ b/drivers/of/device.c
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@@ -9,6 +9,9 @@
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/slab.h>
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+#include <linux/pci.h>
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+#include <linux/platform_device.h>
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+#include <linux/amba/bus.h>
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#include <asm/errno.h>
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#include "of_private.h"
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@@ -84,31 +87,28 @@ int of_device_add(struct platform_device *ofdev)
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*/
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int of_dma_configure(struct device *dev, struct device_node *np)
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{
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- u64 dma_addr, paddr, size;
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+ u64 dma_addr, paddr, size = 0;
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int ret;
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bool coherent;
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unsigned long offset;
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const struct iommu_ops *iommu;
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u64 mask;
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- /*
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- * Set default coherent_dma_mask to 32 bit. Drivers are expected to
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- * setup the correct supported mask.
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- */
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- if (!dev->coherent_dma_mask)
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- dev->coherent_dma_mask = DMA_BIT_MASK(32);
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-
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- /*
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- * Set it to coherent_dma_mask by default if the architecture
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- * code has not set it.
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- */
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- if (!dev->dma_mask)
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- dev->dma_mask = &dev->coherent_dma_mask;
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-
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ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
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if (ret < 0) {
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+ /*
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+ * For legacy reasons, we have to assume some devices need
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+ * DMA configuration regardless of whether "dma-ranges" is
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+ * correctly specified or not.
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+ */
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+ if (!dev_is_pci(dev) &&
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+#ifdef CONFIG_ARM_AMBA
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+ dev->bus != &amba_bustype &&
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+#endif
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+ dev->bus != &platform_bus_type)
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+ return ret == -ENODEV ? 0 : ret;
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+
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dma_addr = offset = 0;
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- size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
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} else {
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offset = PFN_DOWN(paddr - dma_addr);
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@@ -129,6 +129,22 @@ int of_dma_configure(struct device *dev, struct device_node *np)
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dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
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}
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+ /*
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+ * Set default coherent_dma_mask to 32 bit. Drivers are expected to
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+ * setup the correct supported mask.
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+ */
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+ if (!dev->coherent_dma_mask)
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+ dev->coherent_dma_mask = DMA_BIT_MASK(32);
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+ /*
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+ * Set it to coherent_dma_mask by default if the architecture
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+ * code has not set it.
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+ */
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+ if (!dev->dma_mask)
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+ dev->dma_mask = &dev->coherent_dma_mask;
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+
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+ if (!size)
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+ size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
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+
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dev->dma_pfn_offset = offset;
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/*
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--
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cgit v1.1
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