[PATCH 1/2] firewire: core: expose kernel API to schedule work item to process isochronous context
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From: Takashi S. <o-t...@sa...> - 2024-09-08 04:06:09
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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(). Signed-off-by: Takashi Sakamoto <o-t...@sa...> --- Documentation/driver-api/firewire.rst | 2 ++ drivers/firewire/core.h | 5 ----- drivers/firewire/ohci.c | 4 ++-- include/linux/firewire.h | 17 +++++++++++++++++ 4 files changed, 21 insertions(+), 7 deletions(-) diff --git a/Documentation/driver-api/firewire.rst b/Documentation/driver-api/firewire.rst index d3cfa73cbb2b..28a32410f7d2 100644 --- a/Documentation/driver-api/firewire.rst +++ b/Documentation/driver-api/firewire.rst @@ -43,6 +43,8 @@ Firewire core transaction interfaces Firewire Isochronous I/O interfaces =================================== +.. kernel-doc:: include/linux/firewire.h + :functions: fw_iso_context_schedule_flush_completions .. kernel-doc:: drivers/firewire/core-iso.c :export: diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h index 2874f316156a..0ae2c84ecafe 100644 --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -164,11 +164,6 @@ static inline void fw_iso_context_init_work(struct fw_iso_context *ctx, work_fun INIT_WORK(&ctx->work, func); } -static inline void fw_iso_context_queue_work(struct fw_iso_context *ctx) -{ - queue_work(ctx->card->isoc_wq, &ctx->work); -} - /* -topology */ diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index d0b1fccc450f..3a911cfb5ff3 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -2283,7 +2283,7 @@ static irqreturn_t irq_handler(int irq, void *data) while (iso_event) { i = ffs(iso_event) - 1; - fw_iso_context_queue_work(&ohci->ir_context_list[i].base); + fw_iso_context_schedule_flush_completions(&ohci->ir_context_list[i].base); iso_event &= ~(1 << i); } } @@ -2294,7 +2294,7 @@ static irqreturn_t irq_handler(int irq, void *data) while (iso_event) { i = ffs(iso_event) - 1; - fw_iso_context_queue_work(&ohci->it_context_list[i].base); + fw_iso_context_schedule_flush_completions(&ohci->it_context_list[i].base); iso_event &= ~(1 << i); } } diff --git a/include/linux/firewire.h b/include/linux/firewire.h index 72f497b61739..f815d12deda0 100644 --- a/include/linux/firewire.h +++ b/include/linux/firewire.h @@ -531,6 +531,23 @@ int fw_iso_context_queue(struct fw_iso_context *ctx, unsigned long payload); void fw_iso_context_queue_flush(struct fw_iso_context *ctx); int fw_iso_context_flush_completions(struct fw_iso_context *ctx); + +/** + * fw_iso_context_schedule_flush_completions() - schedule work item to process isochronous context. + * @ctx: the isochronous context + * + * Schedule a work item on workqueue to process the isochronous context. The registered callback + * function is called in the worker if some packets have been already transferred since the last + * time. If it is required to process the context in the current context, + * fw_iso_context_flush_completions() is available instead. + * + * Context: Any context. + */ +static inline void fw_iso_context_schedule_flush_completions(struct fw_iso_context *ctx) +{ + queue_work(ctx->card->isoc_wq, &ctx->work); +} + int fw_iso_context_start(struct fw_iso_context *ctx, int cycle, int sync, int tags); int fw_iso_context_stop(struct fw_iso_context *ctx); -- 2.43.0 |