Thread (10 messages) 10 messages, 5 authors, 2018-07-06

Re: [PATCH v4 1/2] ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()

From: Robin Murphy <robin.murphy@arm.com>
Date: 2018-05-31 17:52:48
Also in: dri-devel, linux-arm-kernel, linux-iommu, nouveau

On 30/05/18 15:06, Thierry Reding wrote:
From: Thierry Reding <redacted>

Instead of setting the DMA ops pointer to NULL, set the correct,
non-IOMMU ops depending on the device's coherency setting.
It looks like it's probably been 4 or 5 years since that became subtly 
wrong by virtue of the landscape changing around it, but it's clearly 
not enough of a problem to consider stable backports :)

Reviewed-by: Robin Murphy <robin.murphy@arm.com>
quoted hunk ↗ jump to hunk
Signed-off-by: Thierry Reding <redacted>
---
Changes in v4:
- new patch to fix existing arm_iommu_detach_device() to do what we need

  arch/arm/mm/dma-mapping.c | 12 ++++++------
  1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index af27f1c22d93..87a0037574e4 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1151,6 +1151,11 @@ int arm_dma_supported(struct device *dev, u64 mask)
  	return __dma_supported(dev, mask, false);
  }
  
+static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
+{
+	return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
+}
+
  #ifdef CONFIG_ARM_DMA_USE_IOMMU
  
  static int __dma_info_to_prot(enum dma_data_direction dir, unsigned long attrs)
@@ -2296,7 +2301,7 @@ void arm_iommu_detach_device(struct device *dev)
  	iommu_detach_device(mapping->domain, dev);
  	kref_put(&mapping->kref, release_iommu_mapping);
  	to_dma_iommu_mapping(dev) = NULL;
-	set_dma_ops(dev, NULL);
+	set_dma_ops(dev, arm_get_dma_map_ops(dev->archdata.dma_coherent));
  
  	pr_debug("Detached IOMMU controller from %s device.\n", dev_name(dev));
  }
@@ -2357,11 +2362,6 @@ static void arm_teardown_iommu_dma_ops(struct device *dev) { }
  
  #endif	/* CONFIG_ARM_DMA_USE_IOMMU */
  
-static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
-{
-	return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
-}
-
  void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
  			const struct iommu_ops *iommu, bool coherent)
  {
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