[PATCH v1 3/9] parisc: Convert DMA map_page to map_phys interface
John David Anglin
dave.anglin at bell.net
Sat Oct 4 03:18:32 AEST 2025
On 2025-10-03 11:01 a.m., Jason Gunthorpe wrote:
> This doesn't actually use the virt at all:
>
> offset = ((unsigned long) addr) & ~IOVP_MASK;
> if((size % L1_CACHE_BYTES) || ((unsigned long)addr % L1_CACHE_BYTES))
> ccio_io_pdir_entry(pdir_start, KERNEL_SPACE, (unsigned long)addr, hint);
>
> And ccio_io_pdir_entry():
> pa = lpa(vba);
>
> Is a special instruction that uses virt but AI tells me that special
> LPA instruction is returning phys. Not sure if that is a different
> value than virt_to_phys()..
ccio_io_pdir_entry currently only supports KERNEL_SPACE. For KERNEL_SPACE, lpa() and
virt_to_phys() are equivalent if page is mapped. lpa() returns 0 if a non-access data
TLB fault occurs (i.e., page isn't mapped). Not sure if that matters.
> IDK, I'm not feeling brave enough to drop the LPA but maybe include
> this note in the commit message.
>
--
John David Anglin dave.anglin at bell.net
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