DMA write fails when dma_alloc_coherent is replaced with dma_map_single
I am experimenting the DMA flow with and without SMMU on ARM.
Our custom application requires kernel address, physical address and bus address.
With SMMU enabled, I managed to get the kernel address and bus address using dma_alloc_coherent(), but I could not get the physical address via virt_to_phys().
That made me replace dma_alloc_coherent() with dma_map_single as follows:
// Get kernel address
res->KernelAddress = (u64)kzalloc( size , GFP_KERNEL | GFP_DMA);
// Get bus address
res->BusAddress = (u64)dma_map_single(&DevExt->pdev->dev, &res->KernelAddress, size, PCI_DMA_BIDIRECTIONAL);
// Get physical address
res->PhysicalAddress = (u64)virt_to_phys( (void*)res->KernelAddress );
dma_sync_single_for_cpu(&DevExt->pdev->dev, res->BusAddress, size, PCI_DMA_BIDIRECTIONAL);
// Map physical address to virtual address in user space
if (remap_pfn_range(vma, vma->kern_addr, vma->phys_addr,size,vma->vm_page_prot));
There was no issue with the above flow.
I managed to get 3 addresses but DMA write to the returned location failed.
Are other DMA APIs required for the above flow to work?
It is better if any snippet is shared!
linux-kernel arm dma mmu
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
asked Nov 21 '18 at 10:13
PBangPBang
11
add a comment |
I am experimenting the DMA flow with and without SMMU on ARM.
Our custom application requires kernel address, physical address and bus address.
With SMMU enabled, I managed to get the kernel address and bus address using dma_alloc_coherent(), but I could not get the physical address via virt_to_phys().
That made me replace dma_alloc_coherent() with dma_map_single as follows:
// Get kernel address
res->KernelAddress = (u64)kzalloc( size , GFP_KERNEL | GFP_DMA);
// Get bus address
res->BusAddress = (u64)dma_map_single(&DevExt->pdev->dev, &res->KernelAddress, size, PCI_DMA_BIDIRECTIONAL);
// Get physical address
res->PhysicalAddress = (u64)virt_to_phys( (void*)res->KernelAddress );
dma_sync_single_for_cpu(&DevExt->pdev->dev, res->BusAddress, size, PCI_DMA_BIDIRECTIONAL);
// Map physical address to virtual address in user space
if (remap_pfn_range(vma, vma->kern_addr, vma->phys_addr,size,vma->vm_page_prot));
There was no issue with the above flow.
I managed to get 3 addresses but DMA write to the returned location failed.
Are other DMA APIs required for the above flow to work?
It is better if any snippet is shared!
linux-kernel arm dma mmu
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
asked Nov 21 '18 at 10:13
PBangPBang
11
kzallocshould work withvirt_to_phys; something is wrong with your system if not. If you tryvirt_to_physon another address range, it may not work. See: Physical address of vector table for alternatives tovirt_to_phys.
– artless noise
Nov 21 '18 at 14:10
Is the flow correct? Should remap_pfn_range be changed to dma_mmap_coherent? But, dma_mmap_coherent expects the bus address not the physical address, doesn't it? Does vma_area_struct maintain bus address (dma_addr_t) details?
– PBang
Nov 22 '18 at 10:26
Can you please comment on this?
– PBang
Nov 26 '18 at 10:05
I don’t see how you check for errors of DMA API calls.
– 0andriy
Dec 1 '18 at 10:27
add a comment |
I am experimenting the DMA flow with and without SMMU on ARM.
Our custom application requires kernel address, physical address and bus address.
With SMMU enabled, I managed to get the kernel address and bus address using dma_alloc_coherent(), but I could not get the physical address via virt_to_phys().
That made me replace dma_alloc_coherent() with dma_map_single as follows:
// Get kernel address
res->KernelAddress = (u64)kzalloc( size , GFP_KERNEL | GFP_DMA);
// Get bus address
res->BusAddress = (u64)dma_map_single(&DevExt->pdev->dev, &res->KernelAddress, size, PCI_DMA_BIDIRECTIONAL);
// Get physical address
res->PhysicalAddress = (u64)virt_to_phys( (void*)res->KernelAddress );
dma_sync_single_for_cpu(&DevExt->pdev->dev, res->BusAddress, size, PCI_DMA_BIDIRECTIONAL);
// Map physical address to virtual address in user space
if (remap_pfn_range(vma, vma->kern_addr, vma->phys_addr,size,vma->vm_page_prot));
There was no issue with the above flow.
I managed to get 3 addresses but DMA write to the returned location failed.
Are other DMA APIs required for the above flow to work?
It is better if any snippet is shared!
linux-kernel arm dma mmu
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
asked Nov 21 '18 at 10:13
PBangPBang
11
I am experimenting the DMA flow with and without SMMU on ARM.
Our custom application requires kernel address, physical address and bus address.
With SMMU enabled, I managed to get the kernel address and bus address using dma_alloc_coherent(), but I could not get the physical address via virt_to_phys().
That made me replace dma_alloc_coherent() with dma_map_single as follows:
// Get kernel address
res->KernelAddress = (u64)kzalloc( size , GFP_KERNEL | GFP_DMA);
// Get bus address
res->BusAddress = (u64)dma_map_single(&DevExt->pdev->dev, &res->KernelAddress, size, PCI_DMA_BIDIRECTIONAL);
// Get physical address
res->PhysicalAddress = (u64)virt_to_phys( (void*)res->KernelAddress );
dma_sync_single_for_cpu(&DevExt->pdev->dev, res->BusAddress, size, PCI_DMA_BIDIRECTIONAL);
// Map physical address to virtual address in user space
if (remap_pfn_range(vma, vma->kern_addr, vma->phys_addr,size,vma->vm_page_prot));
There was no issue with the above flow.
I managed to get 3 addresses but DMA write to the returned location failed.
Are other DMA APIs required for the above flow to work?
It is better if any snippet is shared!
linux-kernel arm dma mmu
linux-kernel arm dma mmu
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
asked Nov 21 '18 at 10:13
PBangPBang
11
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
asked Nov 21 '18 at 10:13
PBangPBang
11
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
edited Nov 21 '18 at 14:05
artless noise
15.3k44679
15.3k44679
asked Nov 21 '18 at 10:13
PBangPBang
11
asked Nov 21 '18 at 10:13
PBangPBang
11
asked Nov 21 '18 at 10:13
PBangPBang
11
11
kzallocshould work withvirt_to_phys; something is wrong with your system if not. If you tryvirt_to_physon another address range, it may not work. See: Physical address of vector table for alternatives tovirt_to_phys.
– artless noise
Nov 21 '18 at 14:10
Is the flow correct? Should remap_pfn_range be changed to dma_mmap_coherent? But, dma_mmap_coherent expects the bus address not the physical address, doesn't it? Does vma_area_struct maintain bus address (dma_addr_t) details?
– PBang
Nov 22 '18 at 10:26
Can you please comment on this?
– PBang
Nov 26 '18 at 10:05
I don’t see how you check for errors of DMA API calls.
– 0andriy
Dec 1 '18 at 10:27
add a comment |
kzallocshould work withvirt_to_phys; something is wrong with your system if not. If you tryvirt_to_physon another address range, it may not work. See: Physical address of vector table for alternatives tovirt_to_phys.
– artless noise
Nov 21 '18 at 14:10
Is the flow correct? Should remap_pfn_range be changed to dma_mmap_coherent? But, dma_mmap_coherent expects the bus address not the physical address, doesn't it? Does vma_area_struct maintain bus address (dma_addr_t) details?
– PBang
Nov 22 '18 at 10:26
Can you please comment on this?
– PBang
Nov 26 '18 at 10:05
I don’t see how you check for errors of DMA API calls.
– 0andriy
Dec 1 '18 at 10:27
kzalloc should work with virt_to_phys; something is wrong with your system if not. If you try virt_to_phys on another address range, it may not work. See: Physical address of vector table for alternatives to virt_to_phys.– artless noise
Nov 21 '18 at 14:10
kzalloc should work with virt_to_phys; something is wrong with your system if not. If you try virt_to_phys on another address range, it may not work. See: Physical address of vector table for alternatives to virt_to_phys.– artless noise
Nov 21 '18 at 14:10
Is the flow correct? Should remap_pfn_range be changed to dma_mmap_coherent? But, dma_mmap_coherent expects the bus address not the physical address, doesn't it? Does vma_area_struct maintain bus address (dma_addr_t) details?
– PBang
Nov 22 '18 at 10:26
Is the flow correct? Should remap_pfn_range be changed to dma_mmap_coherent? But, dma_mmap_coherent expects the bus address not the physical address, doesn't it? Does vma_area_struct maintain bus address (dma_addr_t) details?
– PBang
Nov 22 '18 at 10:26
Can you please comment on this?
– PBang
Nov 26 '18 at 10:05
Can you please comment on this?
– PBang
Nov 26 '18 at 10:05
I don’t see how you check for errors of DMA API calls.
– 0andriy
Dec 1 '18 at 10:27
I don’t see how you check for errors of DMA API calls.
– 0andriy
Dec 1 '18 at 10:27
add a comment |
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kzallocshould work withvirt_to_phys; something is wrong with your system if not. If you tryvirt_to_physon another address range, it may not work. See: Physical address of vector table for alternatives tovirt_to_phys.– artless noise
Nov 21 '18 at 14:10
Is the flow correct? Should remap_pfn_range be changed to dma_mmap_coherent? But, dma_mmap_coherent expects the bus address not the physical address, doesn't it? Does vma_area_struct maintain bus address (dma_addr_t) details?
– PBang
Nov 22 '18 at 10:26
Can you please comment on this?
– PBang
Nov 26 '18 at 10:05
I don’t see how you check for errors of DMA API calls.
– 0andriy
Dec 1 '18 at 10:27