[PATCH v2] usb: devio: fix mmap() on non-coherent DMA architectures

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From: Gavin Li <gavinli@xxxxxxxxxxxxxx>

On architectures that are not (or are optionally) DMA coherent,
dma_alloc_coherent() returns an address into the vmalloc space,
and calling virt_to_phys() on this address returns an unusable
physical address.

This patch replaces the raw remap_pfn_range() call with a call to
dmap_mmap_coherent(), which takes care of the differences between
coherent and non-coherent code paths.

Tested on an arm64 rk3399 board.
---
 drivers/usb/core/devio.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 6833c918abce..9d0043dd8e64 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -250,11 +250,10 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
 	usbm->vma_use_count = 1;
 	INIT_LIST_HEAD(&usbm->memlist);
 
-	if (remap_pfn_range(vma, vma->vm_start,
-			virt_to_phys(usbm->mem) >> PAGE_SHIFT,
-			size, vma->vm_page_prot) < 0) {
+	ret = dma_mmap_coherent(ps->dev->bus->sysdev, vma, mem, dma_handle, size);
+	if (ret) {
 		dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
-		return -EAGAIN;
+		return ret;
 	}
 
 	vma->vm_flags |= VM_IO;
-- 
2.26.2




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