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    Subject[PATCH v5 0/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer
    Date
    DMA cocherency slows the transfer down on systems without hardware coherent
    DMA. In order to demontrate this we introduce performance measurement
    facilities in patch 1 and fix the performance issue in patch 2 in order to
    obtain 4 times speedup.

    Changes since v4:
    * fix fields order in trace events
    * minor style fixes

    Changes since v3:
    * fix scripts/checkpatch.pl errors
    * use __string to store name in trace events

    Changes since v2:
    * use dma_sync_single_for_cpu() to achive better performance
    * remeasured performance

    Changes since v1:
    * trace_pwc_handler_exit() call moved to proper place
    * detailed description added for commit 1
    * additional output added to trace to track separate frames

    Matwey V. Kornilov (2):
    media: usb: pwc: Introduce TRACE_EVENTs for pwc_isoc_handler()
    media: usb: pwc: Don't use coherent DMA buffers for ISO transfer

    drivers/media/usb/pwc/pwc-if.c | 64 ++++++++++++++++++++++++++++++++---------
    include/trace/events/pwc.h | 65 ++++++++++++++++++++++++++++++++++++++++++
    2 files changed, 116 insertions(+), 13 deletions(-)
    create mode 100644 include/trace/events/pwc.h

    --
    2.16.4

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