[PATCH 3.10 074/173] ioatdma: fix selection of 16 vs 8 source path

Greg Kroah-Hartman
2013-12-02T21:00:52Z

From: Dan Williams <dan.j.williams@intel.com>

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>

---
drivers/dma/ioat/dma_v3.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)

--- a/drivers/dma/ioat/dma_v3.c
+++ b/drivers/dma/ioat/dma_v3.c
@@ -1169,9 +1169,6 @@ __ioat3_prep_pq16_lock(struct dma_chan *
u8 op;
int i, s, idx, num_descs;

- /* this function only handles src_cnt 9 - 16 */
- BUG_ON(src_cnt < 9);
-
/* this function is only called with 9-16 sources */
op = result ? IOAT_OP_PQ_VAL_16S : IOAT_OP_PQ_16S;

@@ -1257,13 +1254,21 @@ __ioat3_prep_pq16_lock(struct dma_chan *
return &desc->txd;
}

+static int src_cnt_flags(unsigned int src_cnt, unsigned long flags)
+{
+ if (dmaf_p_disabled_continue(flags))
+ return src_cnt + 1;
+ else if (dmaf_continue(flags))
+ return src_cnt + 3;
+ else
+ return src_cnt;
+}
+
static struct dma_async_tx_descriptor *
ioat3_prep_pq(struct dma_chan *chan, dma_addr_t *dst, dma_addr_t *src,
unsigned int src_cnt, const unsigned char *scf, size_t len,
unsigned long flags)
{
- struct dma_device *dma = chan->device;
-
/* specify valid address for disabled result */
if (flags & DMA_PREP_PQ_DISABLE_P)
dst[0] = dst[1];
@@ -1283,7 +1288,7 @@ ioat3_prep_pq(struct dma_chan *chan, dma
single_source_coef[0] = scf[0];
single_source_coef[1] = 0;

- return (src_cnt > 8) && (dma->max_pq > 8) ?
+ return src_cnt_flags(src_cnt, flags) > 8 ?
__ioat3_prep_pq16_lock(chan, NULL, dst, single_source,
2, single_source_coef, len,
flags) :
@@ -1291,7 +1296,7 @@ ioat3_prep_pq(struct dma_chan *chan, dma
single_source_coef, len, flags);

} else {
- return (src_cnt > 8) && (dma->max_pq > 8) ?
+ return src_cnt_flags(src_cnt, flags) > 8 ?
__ioat3_prep_pq16_lock(chan, NULL, dst, src, src_cnt,
scf, len, flags) :
__ioat3_prep_pq_lock(chan, NULL, dst, src, src_cnt,
@@ -1304,8 +1309,6 @@ ioat3_prep_pq_val(struct dma_chan *chan,
unsigned int src_cnt, const unsigned char *scf, size_t len,
enum sum_check_flags *pqres, unsigned long flags)
{
- struct dma_device *dma = chan->device;
-
/* specify valid address for disabled result */
if (flags & DMA_PREP_PQ_DISABLE_P)
pq[0] = pq[1];
@@ -1317,7 +1320,7 @@ ioat3_prep_pq_val(struct dma_chan *chan,
*/
*pqres = 0;

- return (src_cnt > 8) && (dma->max_pq > 8) ?
+ return src_cnt_flags(src_cnt, flags) > 8 ?
__ioat3_prep_pq16_lock(chan, pqres, pq, src, src_cnt, scf, len,
flags) :
__ioat3_prep_pq_lock(chan, pqres, pq, src, src_cnt, scf, len,
@@ -1328,7 +1331,6 @@ static struct dma_async_tx_descriptor *
ioat3_prep_pqxor(struct dma_chan *chan, dma_addr_t dst, dma_addr_t *src,
unsigned int src_cnt, size_t len, unsigned long flags)
{
- struct dma_device *dma = chan->device;
unsigned char scf[src_cnt];
dma_addr_t pq[2];

@@ -1337,7 +1339,7 @@ ioat3_prep_pqxor(struct dma_chan *chan,
flags |= DMA_PREP_PQ_DISABLE_Q;
pq[1] = dst; /* specify valid address for disabled result */

- return (src_cnt > 8) && (dma->max_pq > 8) ?
+ return src_cnt_flags(src_cnt, flags) > 8 ?
__ioat3_prep_pq16_lock(chan, NULL, pq, src, src_cnt, scf, len,
flags) :
__ioat3_prep_pq_lock(chan, NULL, pq, src, src_cnt, scf, len,
@@ -1349,7 +1351,6 @@ ioat3_prep_pqxor_val(struct dma_chan *ch
unsigned int src_cnt, size_t len,
enum sum_check_flags *result, unsigned long flags)
{
- struct dma_device *dma = chan->device;
unsigned char scf[src_cnt];
dma_addr_t pq[2];

@@ -1363,8 +1364,7 @@ ioat3_prep_pqxor_val(struct dma_chan *ch
flags |= DMA_PREP_PQ_DISABLE_Q;
pq[1] = pq[0]; /* specify valid address for disabled result */

-
- return (src_cnt > 8) && (dma->max_pq > 8) ?
+ return src_cnt_flags(src_cnt, flags) > 8 ?
__ioat3_prep_pq16_lock(chan, result, pq, &src[1], src_cnt - 1,
scf, len, flags) :
__ioat3_prep_pq_lock(chan, result, pq, &src[1], src_cnt - 1,