write_ipc_to_queue(9)

💌 write_ipc_to_queue(9) 💌

okay so bestie, welcome to the Kernel API Manual — this one's write_ipc_to_queue(9) and it's lowkey iconic. it lives in the ISHTP (Intel Smart Sound Technology HID) IPC layer and it's basically the little function that shoves your message into the Tx queue and then goes "okay who's next". let's get into it 🫶

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✨ NAME ✨

write_ipc_to_queue — write ipc msg to Tx queue 🎀

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🌸 SYNOPSIS 🌸

int write_ipc_to_queue (struct ishtp_device *dev , void
(*ipc_send_compl)(void *) , void *ipc_send_compl_prm , unsigned char
*msg , int length );

like, read it out loud, it's giving "function signature that ate" 💅

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🦋 ARGUMENTS 🦋

• dev — the ishtp device instance. your main character struct, the one you're doing all this for ✨
• ipc_send_compl — the send complete callback. this gets called when the send is done, fr fr
• ipc_send_compl_prm — the parameter you hand over to that send complete callback. it's the little gift you pass along 🎁
• msg — pointer to message. the actual payload, the star of the show 👑
• length — length of message. how many bytes of msg we're workin' with 📏

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💜 DESCRIPTION 💜

so here's the vibe: it takes a msg that already has the IPC header (and the upper protocol header too, iykyk) and adds it to the device's Tx-to-write list. then it tries to send the first IPC waiting msg — but only if DRBL is cleared. no cap, that's the whole flow 💫

this function returns a negative value for failure — which means either the free list is empty, or the msg is too long 😭 — and 0 for success. slay.

⚠️ heads up bestie: negative = something went wrong (empty free list, or msg too long). 0 = we thrive. don't mix those up 💀

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🔥 RETURN 🔥

0 for success, else a failure code. that's it, that's the return value 🧚

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🌈 SEE ALSO 🌈

it's all in the kernel file ./drivers/hid/intel-ish-hid/ipc/ipc.c, and honestly the whole friend group is here:

ish_reg_read(9), ish_reg_write(9), _ish_read_fw_sts_reg(9), check_generated_interrupt(9), ish_is_input_ready(9), set_host_ready(9), ishtp_fw_is_ready(9), ish_set_host_rdy(9), ish_clr_host_rdy(9), ish_set_host_ready(9), _ishtp_read_hdr(9), _ishtp_read(9), write_ipc_from_queue(9), ipc_send_mng_msg(9), timed_wait_for_timeout(9), ish_fw_reset_handler(9), fw_reset_work_fn(9), _ish_sync_fw_clock(9), recv_ipc(9), ish_irq_handler(9), ish_disable_dma(9), ish_wakeup(9), _ish_hw_reset(9), _ish_ipc_reset(9), ish_hw_start(9), ish_ipc_get_header(9), _dma_no_cache_snooping(9), ish_dev_init(9), ish_device_disable(9)

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okay that's the whole page, go read the source bestie, it's right there in ./drivers/hid/intel-ish-hid/ipc and this lil' gem was dated October 2026 🌸 — mwah, ily, now go write some ipc msgs to that Tx queue 💖✨🎀