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author | Dan Williams <dan.j.williams@intel.com> | 2013-11-13 10:37:36 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-04 10:56:45 -0800 |
commit | 36dabd38dc3432fdb0c922357a60f9331c9334f4 (patch) | |
tree | 220592220e801fe9e464c5424d52fa2fea08758e /usr | |
parent | b8e15d48cdbbac38b5815b95dd99ac85a0b05edb (diff) |
ioatdma: fix selection of 16 vs 8 source path
commit 21e96c7313486390c694919522a76dfea0a86c59 upstream.
When performing continuations there are implied sources that need to be
added to the source count. Quoting dma_set_maxpq:
/* dma_maxpq - reduce maxpq in the face of continued operations
* @dma - dma device with PQ capability
* @flags - to check if DMA_PREP_CONTINUE and DMA_PREP_PQ_DISABLE_P are set
*
* When an engine does not support native continuation we need 3 extra
* source slots to reuse P and Q with the following coefficients:
* 1/ {00} * P : remove P from Q', but use it as a source for P'
* 2/ {01} * Q : use Q to continue Q' calculation
* 3/ {00} * Q : subtract Q from P' to cancel (2)
*
* In the case where P is disabled we only need 1 extra source:
* 1/ {01} * Q : use Q to continue Q' calculation
*/
...fix the selection of the 16 source path to take these implied sources
into account.
Note this also kills the BUG_ON(src_cnt < 9) check in
__ioat3_prep_pq16_lock(). Besides not accounting for implied sources
the check is redundant given we already made the path selection.
Cc: Dave Jiang <dave.jiang@intel.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'usr')
0 files changed, 0 insertions, 0 deletions