__comedi_ch...quest_region(9)

🌸 __comedi_check_request_region(9) — Kernel API Manual 🌸

okay bestie, welcome to the Kernel API Manual, sit down, hydrate, and let's talk about reserving I/O ports 💅

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✨ NAME ✨

__comedi_check_request_region — request an I/O region for a legacy driver 🎀

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💖 SYNOPSIS 💖

int __comedi_check_request_region (struct comedi_device *dev , unsigned long start , unsigned long len , unsigned long minstart , unsigned long maxend , unsigned long minalign );

like yes it's a long signature, no we're not scared of it 💀

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🦋 ARGUMENTS 🦋

• dev — the COMEDI device. your main character struct, the whole reason we're here 👑
• start — base address of the I/O region. where it all begins ✨
• len — length of the I/O region. how much real estate we're claiming 🏠
• minstart — minimum allowed start address of region. the floor, bestie, you cannot go below it 🙅
• maxend — maximum allowed region end address of region. the ceiling, and no, you can't just vibe your way past it 😭
• minalign — required alignment for base address. everything has to line up, it's giving grid aesthetics 🌈

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🌸 DESCRIPTION 🌸

So what does this thing do? It requests the specified I/O port region — but not just any region, okay? this one has standards 💅

The region:

• must start at a non-zero address (zero is not it, zero is the ick)
• must fall within the specified bounds
• must be correctly aligned

and if all of that checks out, the request goes through. slay 🫶

Returns 0 on success — iconic, we love a zero 💖

Returns -EINVAL if start is 0 🚫

Returns -EIO if the request fails 😭

heads up bestie: -EINVAL is literally the "your start address is zero" error, and -EIO means the request itself failed. don't mix them up, iykyk 💀

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⭐ SEE ALSO ⭐

Kernel file ./drivers/comedi/drivers.c, plus the whole friend group 👯‍♀️:

• comedi_set_hw_dev(9)
• comedi_alloc_devpriv(9)
• comedi_alloc_subdevices(9)
• comedi_alloc_subdev_readback(9)
• comedi_readback_insn_read(9)
• comedi_timeout(9)
• comedi_dio_insn_config(9)
• comedi_dio_update_state(9)
• comedi_bytes_per_scan_cmd(9)
• comedi_bytes_per_scan(9)
• comedi_nscans_left(9)
• comedi_nsamples_left(9)
• comedi_inc_scan_progress(9)
• comedi_handle_events(9)
• comedi_load_firmware(9)
• comedi_check_request_region(9)
• comedi_legacy_detach(9)
• comedi_auto_config(9)
• comedi_auto_unconfig(9)
• comedi_driver_register(9)
• comedi_driver_unregister(9)

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and that's the whole page, bestie 🎀 this one lives over in ./drivers/comedi, and it was last touched October 2026 — so go forth, request your I/O regions responsibly, and remember: non-zero start, inside the bounds, correctly aligned. periodt 💜✨🦋