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author | Ira Snyder <iws@ovro.caltech.edu> | 2009-05-15 14:27:16 -0700 |
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committer | Li Yang <leoli@freescale.com> | 2009-05-22 16:51:28 +0800 |
commit | bcfb7465c03a8c62c89da374677df56f6b894d44 (patch) | |
tree | 70194cbfab5fb172bcbf7b8443082a721589f04c /Kbuild | |
parent | 138ef0185177a6d221d24b6aa8f12d867fbbef90 (diff) |
fsldma: fix infinite loop on multi-descriptor DMA chain completion
When creating a DMA transaction with multiple descriptors, the async_tx
cookie is set to 0 for each descriptor in the chain, excluding the last
descriptor, whose cookie is set to -EBUSY.
When fsl_dma_tx_submit() is run, it only assigns a cookie to the first
descriptor. All of the remaining descriptors keep their original value,
including the last descriptor, which is set to -EBUSY.
After the DMA completes, the driver will update the last completed cookie
to be -EBUSY, which is an error code instead of a valid cookie. This causes
dma_async_is_complete() to always return DMA_IN_PROGRESS.
This causes the fsldma driver to never cleanup the queue of link
descriptors, and the driver will re-run the DMA transaction on the hardware
each time it receives the End-of-Chain interrupt. This causes an infinite
loop.
With this patch, fsl_dma_tx_submit() is changed to assign a cookie to every
descriptor in the chain. The rest of the code then works without problems.
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Li Yang <leoli@freescale.com>
Diffstat (limited to 'Kbuild')
0 files changed, 0 insertions, 0 deletions