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author | Dan Williams <dan.j.williams@intel.com> | 2009-09-08 17:42:51 -0700 |
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committer | Dan Williams <dan.j.williams@intel.com> | 2009-09-08 17:42:51 -0700 |
commit | 4546ea8f2c1e2d643de2fb70d29aa276a1bc2051 (patch) | |
tree | 48491890fbc24e098eb5f660a7ce90cfbac27166 /crypto/scatterwalk.c | |
parent | e4545ca3b1f4ac0b044e063121c1208b18eca860 (diff) | |
download | linux-crypto-4546ea8f2c1e2d643de2fb70d29aa276a1bc2051.tar.gz linux-crypto-4546ea8f2c1e2d643de2fb70d29aa276a1bc2051.zip |
dmaengine, async_tx: add a "no channel switch" allocator
Channel switching is problematic for some dmaengine drivers as the
architecture precludes separating the ->prep from ->submit. In these
cases the driver can select ASYNC_TX_DISABLE_CHANNEL_SWITCH to modify
the async_tx allocator to only return channels that support all of the
required asynchronous operations.
For example MD_RAID456=y selects support for asynchronous xor, xor
validate, pq, pq validate, and memcpy. When
ASYNC_TX_DISABLE_CHANNEL_SWITCH=y any channel with all these
capabilities is marked DMA_ASYNC_TX allowing async_tx_find_channel() to
quickly locate compatible channels with the guarantee that dependency
chains will remain on one channel. When
ASYNC_TX_DISABLE_CHANNEL_SWITCH=n async_tx_find_channel() may select
channels that lead to operation chains that need to cross channel
boundaries using the async_tx channel switch capability.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'crypto/scatterwalk.c')
0 files changed, 0 insertions, 0 deletions