fw_send_request(9)

💖 fw_send_request(9) 💖

okay bestie, so this is a page straight out of the Kernel API Manual — like, kernel-level FireWire stuff, we're literally in the (9) section, the big-leagues dev docs. sit down, grab a strawberry drink 🍓, and let's get into it ✨

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🎀 NAME 🎀

fw_send_request — submit a request packet for transmission, so it generates a callback for the response subaction, and it does it without a time stamp. no cap, that's the whole vibe of this function 💅

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🌸 SYNOPSIS 🌸

void fw_send_request (struct fw_card *card , struct fw_transaction *t ,
int tcode , int destination_id , int generation , int speed , unsigned
long long offset , void *payload , size_t length ,
fw_transaction_callback_t callback , void *callback_data );

she's a void, she takes eleven arguments, she's iconic 👑

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🦋 ARGUMENTS 🦋

• card — the interface you're sending the request at 🫶
• t — the transaction instance this request belongs to
• tcode — the transaction code, iykyk
• destination_id — the destination node ID, and yes it's made up of bus_ID and phy_ID
• generation — the bus generation during which the request and the response are valid, so don't go mixing generations bestie 😭
• speed — transmission speed, vroom 🏎️
• offset — a 48bit wide offset into the destination's address space (yes, 48bit, she's wide)
• payload — the data payload for the request subaction
• length — length of that payload, in bytes
• callback — the function that gets called when the transaction is completed 💖
• callback_data — data passed along to that transaction completion callback

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✨ DESCRIPTION ✨

so this is a variation of __fw_send_request, except it generates the callback for the response subaction without a time stamp 🎀

now here's the deets on the callback: it's invoked in workqueue context in most cases. BUT — and this is the plot twist 🌈 — if an error is detected before queueing, or if the destination address refers to the local node, then it's invoked in the current context instead. main character energy, honestly 💅

fr fr remember: which context you're in changes based on those two cases — don't assume workqueue every single time 🙈

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🧚 SEE ALSO 🧚

• Kernel file ./include/linux/firewire.h
• fw_send_request_with_tstamp(9)
• fw_iso_context_schedule_flush_completions(9)

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and that's the whole page, bestie 🦋 this one lives under ./include/linux in the Kernel API Manual, dated October 2026 — go forth and send those requests, you absolute icon 👑💜