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| author | Dimitri Sivanich <sivanich@sgi.com> | 2011-05-06 17:33:44 +0200 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2011-05-27 02:11:24 +0200 |
| commit | 19d78a61be6dd707dcec298c486303d4ba2c840a (patch) | |
| tree | 57c0bc50540ec0f49b7b972f14cee51bc4f22e60 /drivers/dma/ioat/dma_v2.c | |
| parent | maintainers: add dma engine tree details (diff) | |
| download | linux-19d78a61be6dd707dcec298c486303d4ba2c840a.tar.xz linux-19d78a61be6dd707dcec298c486303d4ba2c840a.zip | |
x86: poll waiting for I/OAT DMA channel status
For certain system configurations a 5 usec udelay before checking I/OAT DMA
channel status is sometimes not sufficient, resulting in a false failure
status and unnecessary freeing of channel resources. Conversely, for many
configurations 5 usec is longer than necessary.
Loop for up to 20 usec waiting for successful status before failing.
Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma/ioat/dma_v2.c')
| -rw-r--r-- | drivers/dma/ioat/dma_v2.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c index effd140fc042..54d1a3c24e9c 100644 --- a/drivers/dma/ioat/dma_v2.c +++ b/drivers/dma/ioat/dma_v2.c @@ -507,6 +507,7 @@ int ioat2_alloc_chan_resources(struct dma_chan *c) struct ioat_ring_ent **ring; u64 status; int order; + int i = 0; /* have we already been set up? */ if (ioat->ring) @@ -547,8 +548,11 @@ int ioat2_alloc_chan_resources(struct dma_chan *c) ioat2_start_null_desc(ioat); /* check that we got off the ground */ - udelay(5); - status = ioat_chansts(chan); + do { + udelay(1); + status = ioat_chansts(chan); + } while (i++ < 20 && !is_ioat_active(status) && !is_ioat_idle(status)); + if (is_ioat_active(status) || is_ioat_idle(status)) { set_bit(IOAT_RUN, &chan->state); return 1 << ioat->alloc_order; |