From cd78809f6191485a90ea6c92c2b58900ab5c156f Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 17 Dec 2009 13:52:39 -0700 Subject: ioat3: fix p-disabled q-continuation When continuing a pq calculation the driver needs 3 extra sources. The driver can perform a 3 source calculation with a single descriptor, but needs an extended descriptor to process up to 8 sources in one operation. However, in the p-disabled case only one extra source is needed. When continuing a p-disabled operation there are occasions (i.e. 0 < src_cnt % 8 < 3) where the tail operation does not need an extended descriptor. Properly account for this fact otherwise invalid 'dmacount' values will be written to hardware usually causing the channel to halt with 'invalid descriptor' errors. Cc: Signed-off-by: Dan Williams --- drivers/dma/ioat/dma_v3.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'drivers/dma') diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c index 42f6f10fb0c..e58ecb29513 100644 --- a/drivers/dma/ioat/dma_v3.c +++ b/drivers/dma/ioat/dma_v3.c @@ -650,9 +650,11 @@ __ioat3_prep_pq_lock(struct dma_chan *c, enum sum_check_flags *result, num_descs = ioat2_xferlen_to_descs(ioat, len); /* we need 2x the number of descriptors to cover greater than 3 - * sources + * sources (we need 1 extra source in the q-only continuation + * case and 3 extra sources in the p+q continuation case. */ - if (src_cnt > 3 || flags & DMA_PREP_CONTINUE) { + if (src_cnt + dmaf_p_disabled_continue(flags) > 3 || + (dmaf_continue(flags) && !dmaf_p_disabled_continue(flags))) { with_ext = 1; num_descs *= 2; } else -- cgit v1.2.3-70-g09d2