diff options
Diffstat (limited to 'arm-of-restrict-dma-configuration.patch')
| -rw-r--r-- | arm-of-restrict-dma-configuration.patch | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/arm-of-restrict-dma-configuration.patch b/arm-of-restrict-dma-configuration.patch new file mode 100644 index 000000000..cc9ddd965 --- /dev/null +++ b/arm-of-restrict-dma-configuration.patch @@ -0,0 +1,121 @@ +From 723288836628bc1c0855f3bb7b64b1803e4b9e4a Mon Sep 17 00:00:00 2001 +From: Robin Murphy <robin.murphy@arm.com> +Date: Thu, 31 Aug 2017 11:32:54 +0100 +Subject: of: restrict DMA configuration + +Moving DMA configuration to happen later at driver probe time had the +unnoticed side-effect that we now perform DMA configuration for *every* +device represented in DT, rather than only those explicitly created by +the of_platform and PCI code. + +As Christoph points out, this is not really the best thing to do. Whilst +there may well be other DMA-capable buses that can benefit from having +their children automatically configured after the bridge has probed, +there are also plenty of others like USB, MDIO, etc. that definitely do +not support DMA and should not be indiscriminately processed. + +The good news is that in most cases the DT "dma-ranges" property serves +as an appropriate indicator - per a strict interpretation of the spec, +anything lacking a "dma-ranges" property should be considered not to +have a mapping of DMA address space from its children to its parent, +thus anything for which of_dma_get_range() does not succeed does not +need DMA configuration. Certain bus types have a general expectation of +DMA capability and carry a well-established precedent that an absent +"dma-ranges" implies the same as the empty property, so we automatically +opt those in to DMA configuration regardless, to avoid regressing most +existing platforms. + +Fixes: 09515ef5ddad ("of/acpi: Configure dma operations at probe time for platform/amba/pci bus devices") +Reported-by: Christoph Hellwig <hch@lst.de> +Signed-off-by: Robin Murphy <robin.murphy@arm.com> +Acked-by: Rob Herring <robh@kernel.org> +Signed-off-by: Christoph Hellwig <hch@lst.de> +--- + drivers/of/device.c | 48 ++++++++++++++++++++++++++++++++---------------- + 1 file changed, 32 insertions(+), 16 deletions(-) + +diff --git a/drivers/of/device.c b/drivers/of/device.c +index e0a28ea..04c4c95 100644 +--- a/drivers/of/device.c ++++ b/drivers/of/device.c +@@ -9,6 +9,9 @@ + #include <linux/module.h> + #include <linux/mod_devicetable.h> + #include <linux/slab.h> ++#include <linux/pci.h> ++#include <linux/platform_device.h> ++#include <linux/amba/bus.h> + + #include <asm/errno.h> + #include "of_private.h" +@@ -84,31 +87,28 @@ int of_device_add(struct platform_device *ofdev) + */ + int of_dma_configure(struct device *dev, struct device_node *np) + { +- u64 dma_addr, paddr, size; ++ u64 dma_addr, paddr, size = 0; + int ret; + bool coherent; + unsigned long offset; + const struct iommu_ops *iommu; + u64 mask; + +- /* +- * Set default coherent_dma_mask to 32 bit. Drivers are expected to +- * setup the correct supported mask. +- */ +- if (!dev->coherent_dma_mask) +- dev->coherent_dma_mask = DMA_BIT_MASK(32); +- +- /* +- * Set it to coherent_dma_mask by default if the architecture +- * code has not set it. +- */ +- if (!dev->dma_mask) +- dev->dma_mask = &dev->coherent_dma_mask; +- + ret = of_dma_get_range(np, &dma_addr, &paddr, &size); + if (ret < 0) { ++ /* ++ * For legacy reasons, we have to assume some devices need ++ * DMA configuration regardless of whether "dma-ranges" is ++ * correctly specified or not. ++ */ ++ if (!dev_is_pci(dev) && ++#ifdef CONFIG_ARM_AMBA ++ dev->bus != &amba_bustype && ++#endif ++ dev->bus != &platform_bus_type) ++ return ret == -ENODEV ? 0 : ret; ++ + dma_addr = offset = 0; +- size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); + } else { + offset = PFN_DOWN(paddr - dma_addr); + +@@ -129,6 +129,22 @@ int of_dma_configure(struct device *dev, struct device_node *np) + dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); + } + ++ /* ++ * Set default coherent_dma_mask to 32 bit. Drivers are expected to ++ * setup the correct supported mask. ++ */ ++ if (!dev->coherent_dma_mask) ++ dev->coherent_dma_mask = DMA_BIT_MASK(32); ++ /* ++ * Set it to coherent_dma_mask by default if the architecture ++ * code has not set it. ++ */ ++ if (!dev->dma_mask) ++ dev->dma_mask = &dev->coherent_dma_mask; ++ ++ if (!size) ++ size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); ++ + dev->dma_pfn_offset = offset; + + /* +-- +cgit v1.1 + |