[PATCH v2 0/4] stk1160: allocate urb buffs with the DMA noncontiguous API

[Dafna Hirschfeld <dafna.hirschfeld@collabora.com>]

This set replaces urb buffers allocation to use the DMA
noncontiguous API. Similarly to a commit sent to uvc: [1]
This improves performance on ARM while not damaging performance
on other platforms. The cpu performance on ARM
improves because the new API does not cause the cache disable on ARM
while the coherent API do.
Measurements are shown in patch 4/4

[1] https://lkml.org/lkml/2021/3/12/1506

Patches Summary:
* patches 1+2 are bug fixes.
* patch 3 changes the way data is stored. This is a preparation
to patch 4.
* patch 4 is the change of API to use the noncontiguougs.

Changes since v1:
1. reduce line length to be not too longer than 80 char
2. reformulate commit log of patch 4/4 and add measurements results
3. in patch 4, invalidate the vmap range before the direct mapping range.
4. test regressions for patches 1-3 (not including patch 4) and improve vars names
5. patch 2 is a new bug fix I found
6. patch 1 is extended to fix two cases of not allocating all intended urb buffers.

Dafna Hirschfeld (4):
  media: stk1160: fix number of buffers in case not all buffers are
    created
  media: stk1160: If start stream fails, return buffers with
    VB2_BUF_STATE_QUEUED
  media: stk1160: move transfer_buffer and urb to same struct
    'stk1160_urb'
  media: stk1160: use dma_alloc_noncontiguous API

 drivers/media/usb/stk1160/stk1160-core.c  |   2 +-
 drivers/media/usb/stk1160/stk1160-v4l.c   |  16 ++-
 drivers/media/usb/stk1160/stk1160-video.c | 142 ++++++++++++----------
 drivers/media/usb/stk1160/stk1160.h       |  23 +++-
 4 files changed, 104 insertions(+), 79 deletions(-)

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2.17.1