Re: [PATCH 2/2] Added leon3_dma_ops and LEON specific mmu_inval_dma_area

[Kristoffer Glembo <kristoffer@gaisler.com>]

Hi,


David Miller wrote:
> From: Kristoffer Glembo <kristoffer@gaisler.com>
> Date: Wed, 18 Nov 2009 09:45:41 +0100
> 
>> But I noticed that pci_map_single does not work in later kernels.
>> I guess it stopped working with the patch "sparc: Use
>> asm-generic/pci-dma-compat" since before the that the physical address
>> was obtained through virt_to_phys() and after that it goes through
>> page_to_phys(virt_to_page()) which does not work. Using
>> page_address(virt_to_page()) works but I understand that this does not
>> always evaluate properly.
> 
> "page_address(virt_to_page())" returns a virtual address, whereas
> page_to_phys(virt_to_page()) returns a physical one.
> 

Yeah, I meant virt_to_phys(page_address(virt_to_page())) ..


>> Using page_to_phys(virt_to_page()) results in an address lacking the
>> phys_base offset.
> 
> If it's not adding in phys_base, then it's not returning a legal
> physical address.  Any idea why we don't add phys_base here?  I feel
> like we've discussed this exactly recently, like in the past few
> months.


We did yes. You said that mem_map is not offset at phys_base and then of
course we don't need to add it in page_to_phys. Is mem_map not offset
because typically sp_banks[].base_addr = 0? In our case we pass in one
sp_banks entry which has base_addr = 0x40000000.


Best regards,
Kristoffer