[PATCH v4 0/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer

[Matwey V. Kornilov]

From: "Matwey V. Kornilov" <matwey.kornilov@xxxxxxxxx>

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 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 | 63 ++++++++++++++++++++++++++++++++--------
 include/trace/events/pwc.h     | 65 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 116 insertions(+), 12 deletions(-)
 create mode 100644 include/trace/events/pwc.h

-- 
2.16.4