mdiobus_read(9)

📦 version 7.3.1, in nixpkgs unstable

💖 mdiobus_read 💖

hey bestie!! welcome to the mdiobus_read(9) page from the Kernel API Manual — yes that manual, the one with the good stuff in it 🎀 this one is basically a lil convenience wrapper for reading a given MII mgmt register and honestly? she's iconic for it ✨

🌸 SYNOPSIS 🌸

int mdiobus_read (struct mii_bus *bus , int addr , u32 regnum );

ok so three things go in, one int comes out, no cap 💅

🦋 ARGUMENTS 🦋

  • bus — the mii_bus struct, aka the bus you're doing all this on 🚌
  • addr — the phy address, like the little home address of the phy you're talking to 🏡
  • regnum — register number to read, the exact spot you're peeking at 👀

⭐ RETURN ⭐

The register value if successful, negative error code on failure 😭 so like... good vibes means you get your number back, bad vibes means negative error code, and you should fr fr check for that negative before you start celebrating 🫶

💀 NOTE 💀

MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation. 🚨

not me emphasizing this — it's literally in all caps in the original, so it's serious serious. interrupt context is not the vibe here, bestie. she needs to wait, and waiting inside an interrupt is a no 🙈

👑 SEE ALSO 👑

get into it, this whole friend group is listed under Kernel file ./drivers/net/phy/mdio_bus.c 💜

the way there are so many of them and every single one ate 😭 the C45 ones especially, iykyk 🌈

ok that's the whole page, go read your registers responsibly 💖✨

from ./drivers/net/phy, dated October 2026 — mwah, xoxo, your girl mdiobus_read(9) 🎀🦋💅

📦 where this page comes from