On 07-Mar-19 20:53, Jason Gunthorpe wrote:
> On Thu, Mar 07, 2019 at 04:44:32PM +0200, Gal Pressman wrote:
>> On 06-Mar-19 20:34, Jason Gunthorpe wrote:
>>> On Wed, Mar 06, 2019 at 05:55:11PM +0200, Gal Pressman wrote:
>>>> Also, EFA is special in the sense that all sg functions use PAGE_SIZE while EFA
>>>> needs EFA_PAGE_SIZE. I guess it could be solved by passing that as a parameter,
>>>> but that'll probably require some changes in existing API functions
>>>> (__sg_alloc_table_from_pages for example)?
>>>
>>> No, you are supposed to build up the sgl in large chunks and then
>>> fragment it into whatever the HW requires after DMA mapping.
>>
>> That's fine, I'll change the stride to PAGE_SIZE.
>>
>>>
>>> The code as written is wrong, as the IOMMU is free to consolidate the
>>> carefully broken up SGL into a single entry after doing dma_map.
>>>
>>> Fragementation for HW page size limitations must be done after
>>> mapping to use the APIs correctly.
>>
>> It does.
>> When building the chunk list (pbl_chunk_list_create) we iterate each sg element
>> in EFA_PAGE_SIZE strides.
>
> This loop in pbl_chunk_list_create should use Shiraz's stuff, but it
> is OK to update it after his stuff makes it (noting that if Shiraz is
> merged first you have to fix it) this.
Alright.
>
> Mind that the sg offset in that loop is not always zero though.
Right, thanks!
for_each_sg(pages_sgl, sg, sg_dma_cnt, entry) {
npg_in_sg = sg_dma_len(sg) >> EFA_PAGE_SHIFT;
for (i = 0; i < npg_in_sg; i++) {
cur_chunk_buf[page_idx++] = sg_dma_address(sg) +
^
& ~(EFA_PAGE_SIZE - 1) seems right?
(EFA_PAGE_SIZE * i);
if (page_idx == EFA_PAGE_PTRS_PER_CHUNK) {
chunk_idx++;
cur_chunk_buf = chunk_list->chunks[chunk_idx].buf;
page_idx = 0;
}
}
}
