Dogfooding with SoftISP has uncovered two bugs in this series which I'm
posting fixes for.
- The first error:
A simple race condition which to be honest I'm surprised I haven't found
earlier nor has anybody else. Simply stated the order we typically
end up loading CAMSS on boot has masked out the pm_runtime_enable() race
condition that has been present in CAMSS for a long time.
If you blacklist qcom-camss in modules.d and then modprobe after boot,
the race condition shows up easily.
Moving the pm_runtime_enable prior to subdevice registration fixes the
problem.
The second error:
Nomenclature:
- CSIPHY: CSI Physical layer analogue to digital domain serialiser
- CSID: CSI Decoder
- VFE: Video Front End
- RDI: Raw Data Interface
- VC: Virtual Channel
In order to support streaming multiple virtual-channels on the same RDI a
V4L2 provided use_count variable is used to decide whether or not to actually
terminate streaming and release buffers for 'msm_vfe_rdiX'.
Unfortunately use_count indicates the number of times msm_vfe_rdiX has
been opened by user-space not the number of concurrent streams on
msm_vfe_rdiX.
Simply stated use_count and stream_count are two different things.
The silicon enabling code to select between VCs is valid but, a different
solution needs to be found to support _concurrent_ VC streams.
Right now the upstream use_count as-is is breaking the non concurrent VC
case and I don't believe there are upstream users of concurrent VCs on
CAMSS.
This series implements a revert for the invalid use_count check,
retaining the ability to select which VC is active on the RDI.
Dogfooding with libcamera's SoftISP in Hangouts, Zoom and multiple runs
of libcamera's "qcam" application is a very different test-case to the
simple capture of frames we previously did when validating the
'use_count' change.
A partial revert in expectation of a renewed push to fixup that
concurrent VC issue is included.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
---
Bryan O'Donoghue (2):
media: qcom: camss: Remove use_count guard in stop_streaming
media: qcom: camss: Fix ordering of pm_runtime_enable
drivers/media/platform/qcom/camss/camss-video.c | 6 ------
drivers/media/platform/qcom/camss/camss.c | 5 +++--
2 files changed, 3 insertions(+), 8 deletions(-)
---
base-commit: c6ce8f9ab92edc9726996a0130bfc1c408132d47
change-id: 20240713-linux-next-24-07-13-camss-fixes-fa98c0965a5d
Best regards,
--
Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
