spi_optimize_message(9)

✨ spi_optimize_message ✨

okay so real talk, this is a page from the Kernel API Manual and it's about doing your SPI message homework once instead of every single time 💅

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🌸 NAME 🌸

spi_optimize_message — does all the one-time validation and setup for a SPI message, so you never have to do it again bestie 🎀

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🦋 SYNOPSIS 🦋

int spi_optimize_message (struct spi_device *spi , struct spi_message *msg );

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💖 ARGUMENTS 💖

• spi — the device that's gonna be used for the message 🫶
• msg — the message you're optimizing. yes. that one.

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✨ DESCRIPTION ✨

okay so imagine you're a peripheral driver and you keep reusing the same message over and over. instead of redoing all the message prep every single time a transfer happens (exhausting 😭), you can call this and do as much of that prep as possible once. it's giving efficiency. it's giving lower CPU usage. it's giving throughput glow-up 🔥

lowkey important: once a message has been optimized, it cannot be modified — with one single exception: you can still update the contents of any xfer->tx_buf. and no, the pointer can't be changed, only the data in the memory it points to. read that twice bestie 💀

and listen — calls to this function must be balanced with calls to spi_unoptimize_message, otherwise you're leaking resources. fr fr. no cap. don't do that to yourself 🙈

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💅 CONTEXT 💅

it can sleep 😴 (iconic behaviour, honestly)

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⭐ RETURN ⭐

zero on success, else a negative error code 🌈

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👑 SEE ALSO 👑

the whole friend group 💜 — also Kernel file ./drivers/spi/spi.c:

• __spi_register_driver(9)
• spi_alloc_device(9)
• spi_add_device(9)
• spi_new_device(9)
• spi_unregister_device(9)
• spi_register_board_info(9)
• spi_res_alloc(9)
• spi_res_free(9)
• spi_res_add(9)
• spi_res_release(9)
• spi_finalize_current_transfer(9)
• __spi_pump_messages(9)
• spi_pump_messages(9)
• spi_take_timestamp_pre(9)
• spi_take_timestamp_post(9)
• spi_set_thread_rt(9)
• spi_get_next_queued_message(9)
• spi_finalize_current_message(9)
• spi_queued_transfer(9)
• spi_flush_queue(9)
• of_register_spi_devices(9)
• spi_new_ancillary_device(9)
• devm_spi_new_ancillary_device(9)
• acpi_spi_count_resources(9)
• acpi_spi_device_alloc(9)
• spi_target_abort(9)
• __spi_alloc_controller(9)
• __devm_spi_alloc_controller(9)
• spi_get_gpio_descs(9)
• spi_register_controller(9)
• devm_spi_register_controller(9)
• spi_unregister_controller(9)
• spi_replace_transfers(9)
• spi_split_transfers_maxsize(9)
• spi_split_transfers_maxwords(9)
• spi_set_cs_timing(9)
• spi_setup(9)
• spi_unoptimize_message(9)
• devm_spi_optimize_message(9)
• spi_async(9)
• spi_sync(9)
• spi_sync_locked(9)
• spi_bus_lock(9)
• spi_bus_unlock(9)
• spi_write_then_read(9)

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and that's the whole page, bestie 🧚💖 this gem lives in ./drivers/spi and it's dated October 2026 — go optimize something and drink some water 💅🌸✨