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Subject[PATCH 4/5] dma-direct: implement complete bus_dma_mask handling
Date
Instead of rejecting devices with a too small bus_dma_mask we can handle
by taking the bus dma_mask into account for allocations and bounce
buffering decisions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/dma-direct.h | 3 ++-
kernel/dma/direct.c | 21 +++++++++++----------
2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index b79496d8c75b..fbca184ff5a0 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -27,7 +27,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
if (!dev->dma_mask)
return false;

- return addr + size - 1 <= *dev->dma_mask;
+ return addr + size - 1 <=
+ min_not_zero(*dev->dma_mask, dev->bus_dma_mask);
}
#endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 3c404e33d946..64466b7ef67b 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -43,10 +43,11 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
return false;
}

- if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
+ if (*dev->dma_mask >= DMA_BIT_MASK(32) || dev->bus_dma_mask) {
dev_err(dev,
- "%s: overflow %pad+%zu of device mask %llx\n",
- caller, &dma_addr, size, *dev->dma_mask);
+ "%s: overflow %pad+%zu of device mask %llx bus mask %llx\n",
+ caller, &dma_addr, size,
+ *dev->dma_mask, dev->bus_dma_mask);
}
return false;
}
@@ -65,12 +66,18 @@ u64 dma_direct_get_required_mask(struct device *dev)
{
u64 max_dma = phys_to_dma_direct(dev, (max_pfn - 1) << PAGE_SHIFT);

+ if (dev->bus_dma_mask && dev->bus_dma_mask < max_dma)
+ max_dma = dev->bus_dma_mask;
+
return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
}

static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
u64 *phys_mask)
{
+ if (dev->bus_dma_mask && dev->bus_dma_mask < dma_mask)
+ dma_mask = dev->bus_dma_mask;
+
if (force_dma_unencrypted())
*phys_mask = __dma_to_phys(dev, dma_mask);
else
@@ -87,7 +94,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
{
return phys_to_dma_direct(dev, phys) + size - 1 <=
- dev->coherent_dma_mask;
+ min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask);
}

void *dma_direct_alloc_pages(struct device *dev, size_t size,
@@ -291,12 +298,6 @@ int dma_direct_supported(struct device *dev, u64 mask)
if (mask < phys_to_dma(dev, DMA_BIT_MASK(32)))
return 0;
#endif
- /*
- * Upstream PCI/PCIe bridges or SoC interconnects may not carry
- * as many DMA address bits as the device itself supports.
- */
- if (dev->bus_dma_mask && mask > dev->bus_dma_mask)
- return 0;
return 1;
}

--
2.18.0
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