This series goal is to avoid drivers from having ad-hoc code to call .device_run in non-atomic context. Currently, .device_run can be called via v4l2_m2m_job_finish(), not only running in interrupt context, but also creating a nasty re-entrant path into mem2mem drivers. The proposed solution is to add a per-device worker that is scheduled by v4l2_m2m_job_finish, which replaces drivers having a threaded interrupt or similar. This change allows v4l2_m2m_job_finish() to be called in interrupt context, separating .device_run and v4l2_m2m_job_finish() contexts. It's worth mentioning that v4l2_m2m_cancel_job() doesn't need to flush or cancel the new worker, because the job_spinlock synchronizes both and also because the core prevents simultaneous jobs. Either v4l2_m2m_cancel_job() will wait for the worker, or the worker will be unable to run a new job. Patches apply on top of Request API and the Cedrus VPU driver. Tested with cedrus driver using v4l2-request-test and vicodec driver using gstreamer. Ezequiel Garcia (4): mem2mem: Require capture and output mutexes to match v4l2-ioctl.c: Simplify locking for m2m devices v4l2-mem2mem: Avoid calling .device_run in v4l2_m2m_job_finish media: cedrus: Get rid of interrupt bottom-half Sakari Ailus (1): v4l2-mem2mem: Simplify exiting the function in __v4l2_m2m_try_schedule drivers/media/v4l2-core/v4l2-ioctl.c | 47 +------------ drivers/media/v4l2-core/v4l2-mem2mem.c | 66 ++++++++++++------- .../staging/media/sunxi/cedrus/cedrus_hw.c | 26 ++------ 3 files changed, 51 insertions(+), 88 deletions(-) -- 2.19.1
