v2: - Updates commits with Johan's Review/Reported tags - Adds Closes: https://lore.kernel.org/lkml/ZoVNHOTI0PKMNt4_@hovoldconsulting.com - Cc's stable - Adds in suggested kernel log to allow others to more easily match kernel log to fixes - Link to v1: https://lore.kernel.org/r/20240714-linux-next-24-07-13-camss-fixes-v1-0-8f89...
V1: 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@linaro.org --- 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,