kernel/linux.git/include/linux/firewire.h, branch v6.19.11

firewire: core: handle device quirk of TASCAM FW-1884/FW-1804/FW-1082

2025-10-18T03:58:56+00:00

TASCAM FW-1884/FW-1804/FW-1082 is too lazy to repspond to asynchronous request at S400. The asynchronous transaction often results in timeout. This is a problematic quirk. This commit adds support for the quirk. When identifying the new quirk flag, then the transaction speed is configured at S200. Link: https://lore.kernel.org/r/20251018035532.287124-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: handle device quirk of MOTU Audio Express

2025-10-13T14:07:25+00:00

A commit 3a93d082bacf ("ALSA: firewire-motu: add support for MOTU Audio Express") describes a quirk of MOTU Audio Express. The device returns acknowledge packet with 0x10 as the pending state of any types of asynchronous request transaction. It is completely out of specification. This commit implements handling for that device-specific quirk. The quirk is detected after reading the root directory of configuration ROM. When processing the acknowledge code in 1394 OHCI AT context event handler, firewire-ohci module seeks the device instance of destination node by traversing device hierarchy. If the device has the quirk, the acknowledge code is replaced with the standard code. The 1394 OHCI AT context events occur for outgoing asynchronous request packets. The device traversal is safe since no new request initiators exist after the fw_card_instance has been invalidated. Link: https://lore.kernel.org/r/20251013140311.97159-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: detect device quirk when reading configuration ROM

2025-10-13T14:07:24+00:00

Every time the bus manager runs, the cached configuration ROM content of the IRM device is investigated to detect device-specific quirks. This detection can be performed in advance when reading the configuration ROM. This commit adds device quirk flags to the fw_device structure, and initializes them after reading the bus information block of the configuration ROM. The quirk flags are immutable once the configuration ROM has been read. Although they are likely accessed concurrently only by the bus manager, this commit ensures safe access by preventing torn writes and reads using the WRITE_ONCE()/READ_ONCE() macros. Link: https://lore.kernel.org/r/20251013140311.97159-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use spin lock specific to timer for split transaction

2025-09-15T23:52:19+00:00

At present the parameters to compute timeout time for split transaction is protected by card-wide spin lock, while it is not necessarily convenient in a point to narrower critical section. This commit adds and uses another spin lock specific for the purpose. Link: https://lore.kernel.org/r/20250915234747.915922-6-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use spin lock specific to transaction

2025-09-15T23:52:18+00:00

The list of instance for asynchronous transaction to wait for response subaction is maintained as a member of fw_card structure. The card-wide spinlock is used at present for any operation over the list, however it is not necessarily suited for the purpose. This commit adds and uses the spin lock specific to maintain the list. Link: https://lore.kernel.org/r/20250915234747.915922-5-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use spin lock specific to topology map

2025-09-15T23:52:18+00:00

At present, the operation for read transaction to topology map register is not protected by any kind of lock primitives. This causes a potential problem to result in the mixed content of topology map. This commit adds and uses spin lock specific to topology map. Link: https://lore.kernel.org/r/20250915234747.915922-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: maintain phy packet receivers locally in cdev layer

2025-09-15T23:52:18+00:00

The list of receivers for phy packet is used only by cdev layer, while it is maintained as a member of fw_card structure. This commit maintains the list locally in cdev layer. Link: https://lore.kernel.org/r/20250915234747.915922-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use reference counting to invoke address handlers safely

2025-08-11T13:22:33+00:00

The lifetime of address handler has been managed by linked list and RCU. This approach was introduced in commit 35202f7d8420 ("firewire: remove global lock around address handlers, convert to RCU"). The invocations of address handler are performed within RCU read-side critical sections. In commit 57e6d9f85fff ("firewire: ohci: use workqueue to handle events of AR request/response contexts"), the invocations are in a workqueue context. The approach still imposes limitation that sleeping is not allowed within RCU read-side critical sections. However, since sleeping is not permitted within RCU read-side critical sections, this approach still has a limitation. This commit adds reference counting to decouple handler invocation from handler discovery. The linked list and RCU is used to discover the handlers, while the reference counting is used to invoke them safely. Link: https://lore.kernel.org/r/20250803122015.236493-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: ohci: use workqueue to handle events of AT request/response contexts

2025-06-15T13:40:29+00:00

This commit adds a work item to handle events of 1394 OHCI AT request/response contexts, and queues the item to the specific workqueue. The call of struct fw_packet.callbaqck() is done in the workqueue when receiving acknowledgement to the asynchronous packet transferred to remote node. Link: https://lore.kernel.org/r/20250615133253.433057-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: allocate workqueue for AR/AT request/response contexts

2025-06-15T13:40:29+00:00

Some tasklets (softIRQs) are still used as bottom-halves to handle events for 1394 OHCI AR/AT contexts. However, using softIRQs for IRQ bottom halves is generally discouraged today. This commit adds a per-fw_card workqueue to accommodate the behaviour specified by the 1394 OHCI specification. According to the 1394 OHCI specification, system memory pages are reserved for each asynchronous DMA context. This allows concurrent operation across contexts. In the 1394 OHCI PCI driver implementation, the hardware generates IRQs either upon receiving asynchronous packets from other nodes (incoming) or after completing transmission to them (outgoing). These independent events can occur in the same transmission cycle, therefore the max_active parameter for the workqueue is set to the total number of AR/AT contexts (=4). The WQ_UNBOUND flag is used to allow the work to be scheduled on any available core, since there is little CPU cache affinity benefit for the data. Each DMA context uses a circular descriptor list in system memory, allowing deferred data processing in software as long as buffer overrun are avoided. Since the overall operation is sleepable except for small atomic regions, WQ_BH is not used. As the descriptors contain timestamps, WQ_HIGHPRI is specified to support semi-real-time processing. The asynchronous context is also used by the SCSI over IEEE 1394 protocol implementation (sbp2), which can be part of memory reclaim paths. Therefore, WQ_MEM_RECLAIM is required. To allow uses to adjust CPU affinity according to workload, WQ_SYSFS is specified so that workqueue attributes are exposed to user space. Link: https://lore.kernel.org/r/20250615133253.433057-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto