Mixing
Untranslated page fault with pgprot_noncached()
I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.
Currently, I am experimenting with SMMU disabled.
Here is the flow:
ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?
phys_addr = bus_addr;
mmap (...phys_addr);
vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);
remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));
But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.
Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.
Thanks in advance !!
arm dma pci-e
asked Nov 22 '18 at 11:54
PBangPBang
11
add a comment |
I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.
Currently, I am experimenting with SMMU disabled.
Here is the flow:
ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?
phys_addr = bus_addr;
mmap (...phys_addr);
vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);
remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));
But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.
Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.
Thanks in advance !!
arm dma pci-e
asked Nov 22 '18 at 11:54
PBangPBang
11
Can somebody please comment on this?
– PBang
Nov 26 '18 at 10:04
add a comment |
I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.
Currently, I am experimenting with SMMU disabled.
Here is the flow:
ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?
phys_addr = bus_addr;
mmap (...phys_addr);
vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);
remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));
But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.
Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.
Thanks in advance !!
arm dma pci-e
asked Nov 22 '18 at 11:54
PBangPBang
11
I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.
Currently, I am experimenting with SMMU disabled.
Here is the flow:
ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?
phys_addr = bus_addr;
mmap (...phys_addr);
vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);
remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));
But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.
Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.
Thanks in advance !!
arm dma pci-e
arm dma pci-e
asked Nov 22 '18 at 11:54
PBangPBang
11
asked Nov 22 '18 at 11:54
PBangPBang
11
asked Nov 22 '18 at 11:54
PBangPBang
11
asked Nov 22 '18 at 11:54
PBangPBang
11
asked Nov 22 '18 at 11:54
PBangPBang
11
11
Can somebody please comment on this?
– PBang
Nov 26 '18 at 10:04
add a comment |
Can somebody please comment on this?
– PBang
Nov 26 '18 at 10:04
Can somebody please comment on this?
– PBang
Nov 26 '18 at 10:04
Can somebody please comment on this?
– PBang
Nov 26 '18 at 10:04
add a comment |
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Can somebody please comment on this?
– PBang
Nov 26 '18 at 10:04