kernel/linux.git/Documentation/driver-api/firewire.rst, branch v6.18.21

firewire: core: expose kernel API to schedule work item to process isochronous context

2024-09-08T04:05:48+00:00

In packet-per-buffer mode for isochronous context of 1394 OHCI, software can schedule hardIRQ to the buffer in which the content of isochronous packet is processed. The actual behaviour is different between isochronous receive (IR) and transmit (IT) contexts in respect to isochronous cycle in which the hardIRQ occurs. In IR context, the hardIRQ occurs when the buffer is filled actually by the content of received packet. If there are any isochronous cycles in which the packet transmission is skipped, it is postponed to generate the hardIRQ in respect to the isochronous cycle. In IT context, software can schedule the content of packet every isochronous cycle including skipping, therefore the hardIRQ occurs in the isochronous cycle to which the software scheduled. ALSA firewire stack uses the packet-per-buffer mode for both IR/IT contexts. To process time stamp per packet (or per sample in some cases) steadily for media clock recovery against unexpected transmission skips, it uses an IT context to operate all of isochronous contexts by calls of fw_iso_context_flush_completions() in the bottom-half of hardIRQ for the IT context. Although it looks well to handle all of isochronous contexts in a single bottom-half context, it relatively takes longer time. In the future code integration (not yet), it is possible to apply parallelism method to process these context. In the case, it is useful to allow unit drivers to schedule work items to process these isochronous contexts. As a preparation, this commit exposes fw_iso_context_schedule_flush_completions() as a kernel API available by unit drivers. It is renamed from fw_iso_context_queue_work() since it is a counter part of fw_iso_context_flush_completions(). Link: https://lore.kernel.org/r/20240908040549.75304-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

Documentation: fix firewire.rst ABI file path error

2022-01-21T00:01:32+00:00

Adjust the path of the ABI files for firewire.rst to prevent a documentation build error. Prevents this problem: Sphinx parallel build error: docutils.utils.SystemMessage: Documentation/driver-api/firewire.rst:22: (SEVERE/4) Problems with "include" directive path: InputError: [Errno 2] No such file or directory: '../Documentation/driver-api/ABI/stable/firewire-cdev'. Fixes: 2f4830ef96d2 ("FireWire: add driver-api Introduction section") Signed-off-by: Randy Dunlap Tested-by: Akira Yokosawa Link: https://lore.kernel.org/r/20220119033905.4779-1-rdunlap@infradead.org Signed-off-by: Jonathan Corbet

FireWire: add driver-api Introduction section

2018-09-06T15:41:16+00:00

Replace the Introduction section's TBD with some useful overview text. Signed-off-by: Takashi Sakamoto Acked-by: Randy Dunlap Tested-by: Randy Dunlap Signed-off-by: Randy Dunlap Cc: Stefan Richter Cc: Takashi Sakamoto Cc: linux-doc@vger.kernel.org Cc: linux-scsi@vger.kernel.org Cc: Randy Dunlap Cc: Andrew Morton Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: Jonathan Corbet Signed-off-by: Jonathan Corbet

FireWire: add a Documentation driver-api chapter

2018-09-06T15:41:12+00:00

Add a basic Firewire/IEEE 1394 driver API chapter to the Linux kernel documentation. Signed-off-by: Randy Dunlap Cc: Stefan Richter Cc: Takashi Sakamoto Cc: linux-doc@vger.kernel.org Cc: linux-scsi@vger.kernel.org Cc: Randy Dunlap Cc: Andrew Morton Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: Jonathan Corbet Signed-off-by: Jonathan Corbet