comedi_check_request_region(9)

✨ comedi_check_request_region(9) ✨

okay so bestie, we're in the Kernel API Manual today and this one is a lil function called comedi_check_request_region — yes the whole name, it's a mouthful, we love her anyway 💅

---

🌸 NAME 🌸

comedi_check_request_region — request an I/O region for a legacy driver. that's it, that's the vibe 🎀

---

🦋 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 );

---

💖 ARGUMENTS 💖

• dev — the COMEDI device. the main character, honestly 👑
• start — base address of the I/O region. where the region starts, no cap.
• len — length of the I/O region. how much of it there is, fr fr.
• minstart — minimum allowed start address of region. the floor, the boundary, the "don't go below this" energy 🚧
• maxend — maximum allowed region end address of region. the ceiling bestie, the absolute limit.
• minalign — required alignment for base address. everything's gotta line up perfectly, like ✨ symmetry ✨

---

🌈 DESCRIPTION 🌈

so what she does: she requests the specified I/O port region, and the region has a whole checklist to pass 😭 it must start at a non-zero address, it must fall within the specified bounds, and it must be correctly aligned. three rules, no exceptions, periodt.

on success, dev->iobase gets set to the base address of the region and dev->iolen gets set to its length. slay 💅

returns 0 on success, -EINVAL if start is 0, or -EIO if the request fails. like, if it doesn't work out it will literally tell you why 🫶

---

🌟 SEE ALSO 🌟

kernel file ./drivers/comedi/drivers.c — go read her, iykyk 📖 and 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)

---

lowkey the funniest part is that __comedi_check_request_region(9) exists too — the one with the underscores, the blueprint if you will. no notes 💀

---

that's the whole page bestie, go request some regions responsibly 💖 this lil manual lives at ./drivers/comedi, stamped October 2026, and she answers to comedi_check_request_region(9) 🎀✨