diff options
| author | Alex Elder <elder@linaro.org> | 2021-03-28 12:31:10 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-28 18:12:03 -0700 |
| commit | 19aaf72c0c7a26ab7ffc655a6d84da6a379f899b (patch) | |
| tree | 6dac908c510eb28856e9d884b9c6193a7bbd0b9b /drivers/net/ipa/gsi_trans.c | |
| parent | 782d767a2d0fb08bc4d5d26f789769a84b88400b (diff) | |
net: ipa: DMA addresses are nicely aligned
A recent patch avoided doing 64-bit modulo operations by checking
the alignment of some DMA allocations using only the lower 32 bits
of the address.
David Laight pointed out (after the fix was committed) that DMA
allocations might already satisfy the alignment requirements. And
he was right.
Remove the alignment checks that occur after DMA allocation requests,
and update comments to explain why the constraint is satisfied. The
only place IPA_TABLE_ALIGN was used was to check the alignment; it is
therefore no longer needed, so get rid of it.
Add comments where GSI_RING_ELEMENT_SIZE and the tre_count and
event_count channel data fields are defined to make explicit they
are required to be powers of 2.
Revise a comment in gsi_trans_pool_init_dma(), taking into account
that dma_alloc_coherent() guarantees its result is aligned to a page
size (or order thereof).
Don't bother printing an error if a DMA allocation fails.
Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ipa/gsi_trans.c')
| -rw-r--r-- | drivers/net/ipa/gsi_trans.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c index 6c3ed5b17b80..70c2b585f98d 100644 --- a/drivers/net/ipa/gsi_trans.c +++ b/drivers/net/ipa/gsi_trans.c @@ -153,11 +153,10 @@ int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool, size = __roundup_pow_of_two(size); total_size = (count + max_alloc - 1) * size; - /* The allocator will give us a power-of-2 number of pages. But we - * can't guarantee that, so request it. That way we won't waste any - * memory that would be available beyond the required space. - * - * Note that gsi_trans_pool_exit_dma() assumes the total allocated + /* The allocator will give us a power-of-2 number of pages + * sufficient to satisfy our request. Round up our requested + * size to avoid any unused space in the allocation. This way + * gsi_trans_pool_exit_dma() can assume the total allocated * size is exactly (count * size). */ total_size = get_order(total_size) << PAGE_SHIFT; |