[PATCH v1 3/9] parisc: Convert DMA map_page to map_phys interface

[John David Anglin]

On 2025-10-03 1:26 p.m., Jason Gunthorpe wrote:
> On Fri, Oct 03, 2025 at 01:18:32PM -0400, John David Anglin wrote:
>> 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.
> 
> After unfolding everything the expression is
> 
>   lpa(phys_to_virt(pa))
> 
> So if that is always equal to pa then lets just drop it.

If lpa() was replaced by virt_to_phys(), the result would always be equal to pa.  So, I think it
can be dropped.

Dave
-- 
John David Anglin  dave.anglin at bell.net