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    Subject[PATCH v3 0/9] fsldma: lockup fixes
    Date
    Hello everyone,

    I've been chasing random infrequent controller lockups in the fsldma driver
    for a long time. I finally managed to find the problem and fix it. I'm not
    quite sure about the exact sequence of events which causes the race
    condition, but it is related to using the hardware registers to track the
    controller state. See the patch changelogs for more detail.

    The problems were quickly found by turning on DMAPOOL_DEBUG inside
    mm/dmapool.c. This poisons memory allocated with the dmapool API.

    With dmapool poisoning turned on, the dmatest driver would start producing
    failures within a few seconds. After this patchset has been applied, I have
    run several iterations of the 10 threads per channel, 100000 iterations per
    thread test without any problems. I have also tested it with the CARMA
    drivers (posted at linuxppc-dev previously), which make use of the external
    control features.

    While making the previous changes, I noticed that the fsldma driver does
    not respect the automatic DMA unmapping of src and dst buffers. I have
    added support for this feature. This also required a fix to dmatest, which
    was sending incorrect flags.

    The "support async_tx dependencies" patch could be split apart from the
    automatic unmapping patch if it is desirable. They both touch the same
    piece of code, so I thought it was ok to combine them. Let me know.

    I would really like to see this go into 2.6.39. I think we can get it
    reviewed before then. :)

    Much thanks goes to Felix Radensky for testing on a P2020 (85xx DMA IP core).
    I wouldn't have been able to track down the problems on 85xx without his
    dilligent testing.

    v2 -> v3:
    - use chan_dbg() and chan_err() macros for channel printk

    v1 -> v2:
    - reordered patches (dmatest change is first now)
    - fix problems on 85xx controller
    - only set correct bits for 83xx in dma_halt()

    Ira W. Snyder (9):
    dmatest: fix automatic buffer unmap type
    fsldma: move related helper functions near each other
    fsldma: use channel name in printk output
    fsldma: improve link descriptor debugging
    fsldma: minor codingstyle and consistency fixes
    fsldma: fix controller lockups
    fsldma: support async_tx dependencies and automatic unmapping
    fsldma: reduce locking during descriptor cleanup
    fsldma: make halt behave nicely on all supported controllers

    drivers/dma/dmatest.c | 7 +-
    drivers/dma/fsldma.c | 551 +++++++++++++++++++++++++++----------------------
    drivers/dma/fsldma.h | 6 +-
    3 files changed, 311 insertions(+), 253 deletions(-)

    --
    1.7.3.4



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