acpm_set_xfer(9)

💅 acpm_set_xfer(9) — from the Kernel API Manual, bestie

okay so picture this: you're deep in the kernel, you've got a command you NEED to send to the ACPM firmware, and you're standing there like 🧍‍♀️ holding a raw struct with zero clue what goes in it. that's literally this function's whole job. acpm_set_xfer sets up — initializes, if we're being fancy — an ACPM IPC transfer structure. it fills in the blanks so the rest of the pipeline knows where your command lives and whether anyone's expecting a text back. 💌

✨ SYNOPSIS ✨

void acpm_set_xfer (struct acpm_xfer *xfer , u32 *cmd , size_t cmdcnt ,
       unsigned int acpm_chan_id , bool response );

returns nothing (void), which honestly? iconic. it just does the thing and dips. 🫶

🎀 ARGUMENTS 🎀

• xfer — pointer to the ACPM transfer structure that's getting initialized. this is the main character of the operation, bestie. it's the thing you're filling in. ✨
• cmd — pointer to the buffer holding the command you're transmitting to the ACPM firmware. your actual message. the ~content~. 💌
• cmdcnt — length of that command, measured in 32-bit words. note the unit, ngl, it's words not bytes, so don't come at it with sizeof and vibes only. 🙈
• acpm_chan_id — the mailbox channel identifier. basically which door you're knocking on. 🚪
• response — boolean flag saying whether the kernel expects the ACPM firmware to send a reply to this specific command. true = you're waiting by the phone 😭, false = you said what you said and you're moving on 💅

fr fr — if response doesn't match what you actually expect back, that's a you problem, so think it through before you set it.

👑 SEE ALSO 👑

• Kernel file ./drivers/firmware/samsung/exynos-acpm.c
• struct acpm_shmem(9)
• struct acpm_chan_shmem(9)
• struct acpm_queue(9)
• struct acpm_rx_data(9)
• struct acpm_chan(9)
• struct acpm_info(9)
• struct acpm_match_data(9)
• acpm_get_saved_rx(9)
• acpm_get_rx(9)
• acpm_dequeue_by_polling(9)
• acpm_wait_for_queue_slots(9)
• acpm_prepare_xfer(9)
• acpm_wait_for_message_response(9)
• acpm_do_xfer(9)
• acpm_chan_shmem_get_params(9)
• acpm_achan_alloc_cmds(9)
• acpm_free_mbox_chans(9)
• acpm_channels_init(9)
• acpm_handle_put(9)
• devm_acpm_release(9)
• acpm_get_by_node(9)
• devm_acpm_get_by_node(9)
• devm_acpm_get_by_phandle(9)

like, that's the whole friend group right there. go read them, they're all connected, iykyk. 🌈

mwah 💋 that's the page — brought to you by the fine folks over in ./drivers/firmware/samsung, dated October 2026, and yes the manual really does say acpm_set_xfer(9) twice because branding. slay. 💜