[PATCH v3 0/2] media: imx: Stop stream before disabling IDMA channels

[Steve Longerbeam <slongerbeam@gmail.com>]

Repeatedly sending a stream off immediately followed by stream on can
eventually cause a complete system hard lockup on the SabreAuto when
streaming from the ADV7180:

while true; do v4l2-ctl  -d4 --stream-mmap --stream-count=3; done

Eventually this either causes the system lockup or EOF timeouts at all
subsequent stream on, until a system reset.

The lockup occurs when disabling the IDMA channels at stream off. Stopping
the video data stream entering the IDMA channel before disabling the
channel itself appears to be a reliable fix for the hard lockup.

In the CSI subdevice, this can be done by disabling the SMFC before
disabling the CSI IDMA channel, instead of after. In the IC-PRPENVVF
subdevice, this can be done by stopping upstream before disabling the
PRPENC/VF IDMA channel.

History:
v3:
- Switch to disabling the SMFC before the channel, instead of the CSI
  before the channel.

v2:
- Whitespace fixes
- Add Fixes: and Cc: stable@vger.kernel.org
- No functional changes.


Steve Longerbeam (2):
  media: imx: csi: Disable SMFC before disabling IDMA channel
  media: imx: prpencvf: Stop upstream before disabling IDMA channel

 drivers/staging/media/imx/imx-ic-prpencvf.c | 26 ++++++++++++++-------
 drivers/staging/media/imx/imx-media-csi.c   |  2 +-
 2 files changed, 18 insertions(+), 10 deletions(-)

-- 
2.17.1