On Fri, 2019-04-26 at 10:11 +0200, Philipp Zabel wrote: > On Thu, 2019-04-25 at 15:35 -0300, Ezequiel Garcia wrote: > > There isn't any reason to run the mem2mem job on a separate worker, > > because the mem2mem framework guarantees that device_run will never > > run in interrupt context. > > The purpose of the workqueue is to serialize BIT processor commands, > currently the PIC_RUN commands issued by the mem2mem framework (as well > as SEQ_INIT, SET_FRAME_BUF, and ENCODE_HEADER) against the SEQ_END > command issued directly from the STREAMOFF ioctl. Right, but that's serialized by the coda_mutex, not by the worker, right? > Further, to fully support the stateful decoder API we'll have to move > SEQ_INIT out of the mem2mem device_run as well, since that should be > called on queued OUTPUT buffers before the CAPTURE side is even > streaming. > Isn't that already done? I see SEQ_INIT being issued in start_streaming. In what sense is this driver currently violating the decoder spec? So, returning to the serialization. I believe commands are still serialized after this change. The pic_run_work worker is only queued from .device_run. Only one job can run on a context at any given time, but multiple contexts can run in parallel. Inside the worker, the coda_mutex serializes the commands. The worker waits until the command has finished execution. So, with this commit, there is no longer a worker, but commands are still serialized by the mutex and the fact that the command is completed in .device_run. That being said, the worker does makes the serialization more clear, so I think dropping this patch is better. Perhaps adding a small comment so the purpose of pic_run_work is clear. Thanks, Eze
