From: Christoph Hellwig <hch@lst.de>
Date: Wed, 10 Jun 2020 10:29:49 +0200
Subject: dma-direct: re-enable mmap for !CONFIG_MMU
Git-commit: 1fbf57d0530217b9f264eedc4867bf91479cdf3c
Patch-mainline: v5.8-rc3
References: bsc#1175713
nommu configfs can trivially map the coherent allocations to user space,
as no actual page table setup is required and the kernel and the user
space programs share the same address space.
Fixes: 62fcee9a3bd7 ("dma-mapping: remove CONFIG_ARCH_NO_COHERENT_DMA_MMAP")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: dillon min <dillon.minfei@gmail.com>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: dillon min <dillon.minfei@gmail.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
kernel/dma/Kconfig | 1 +
kernel/dma/direct.c | 14 --------------
2 files changed, 1 insertion(+), 14 deletions(-)
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index a0ce3c1494fd..14ef8e1bdefe 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -71,6 +71,7 @@ config SWIOTLB
# in the pagetables
#
config DMA_NONCOHERENT_MMAP
+ default y if !MMU
bool
config DMA_COHERENT_POOL
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 0a4881e59aa7..9ec6a5c3fc57 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -459,7 +459,6 @@ int dma_direct_get_sgtable(struct device *dev, struct sg_table *sgt,
return ret;
}
-#ifdef CONFIG_MMU
bool dma_direct_can_mmap(struct device *dev)
{
return dev_is_dma_coherent(dev) ||
@@ -485,19 +484,6 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
user_count << PAGE_SHIFT, vma->vm_page_prot);
}
-#else /* CONFIG_MMU */
-bool dma_direct_can_mmap(struct device *dev)
-{
- return false;
-}
-
-int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
- void *cpu_addr, dma_addr_t dma_addr, size_t size,
- unsigned long attrs)
-{
- return -ENXIO;
-}
-#endif /* CONFIG_MMU */
int dma_direct_supported(struct device *dev, u64 mask)
{