blk_pm_runtime_init(9)

💅 blk_pm_runtime_init — the Kernel API Manual, bestie edition 🎀

okay so this page is blk_pm_runtime_init(9) from the Kernel API Manual, and honestly? it's giving "tiny function, big responsibilities." let's get into it ✨

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🌸 NAME 🌸

blk_pm_runtime_init — the Block layer runtime PM initialization routine. that's it, that's the name, no notes 💅

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✨ SYNOPSIS ✨

void blk_pm_runtime_init (struct request_queue *q , struct device *dev );

yup, that's the whole signature. void return, two pointers in, vibes out. 🫶

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🎀 ARGUMENTS 🎀

• q — the queue of the device. like, the actual struct request_queue *, not a copy, not a vibe, the real one 🔥
• dev — the device the queue belongs to. q's other half, its main character partner 💖

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🦋 DESCRIPTION 🦋

so what does this thing actually do? it initializes the runtime-PM-related fields for q and starts auto suspend for dev. lowkey iconic of it. ⭐

here's the tea for drivers wanting to take advantage of request-based runtime PM — you call this function when all three of these are true:

1. dev has been initialized ✅
2. its request queue q has been allocated ✅
3. runtime PM for it can not happen yet — either because it's disabled/forbidden, or because its usage_count > 0 ✅

and in most cases? the driver should call this function before any I/O has taken place. like, do it early, bestie. don't be weird about it. 🙈

this function handles setting things up using auto suspend for the device, and here's the spicy detail: the autosuspend delay is set to -1 to make runtime suspend impossible until an updated value is either set by the user or by the driver. so yeah, it's deliberately asleep-at-the-wheel until somebody gives it a real number 💀

the good news: drivers do not need to touch other autosuspend settings. it's handled. you're free. go live your life 🌈

one more thing, and it's important so listen up: the block layer runtime PM is request based, so it only works for drivers that use request as their IO unit — not the ones that directly use bio's. periodt. 🧚

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👑 SEE ALSO 👑

• Kernel file ./block/blk-pm.c
• blk_pre_runtime_suspend(9)
• blk_post_runtime_suspend(9)
• blk_pre_runtime_resume(9)
• blk_post_runtime_resume(9)

go read the whole saga, it's a series 💜

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and that's the page!! this one came from ./block, October 2026, and it's the blk_pm_runtime_init(9) entry in the Kernel API Manual — mwah, slay, see u in the group chat 😭💖🌸