ax_spi_detect_fifo_depth(9)

📦 version 7.3.1, in nixpkgs unstable

💅 ax_spi_detect_fifo_depth — bestie, let's find out how deep this FIFO goes 🎀

Okay so this one is from the Kernel API Manual (section 9, the kernel-functions one, iykyk), and honestly? It's giving "small but mighty". Let's get into it ✨

🌸 NAME 🌸

ax_spi_detect_fifo_depth — literally just detects the FIFO depth of the hardware. That's the whole vibe. No cap 🫶

🦋 SYNOPSIS 🦋

void ax_spi_detect_fifo_depth (struct ax_spi *xspi );

🎀 ARGUMENTS 🎀

  • xspi — a pointer to the ax_spi structure. That's it, that's the whole guest list 💅

✨ DESCRIPTION ✨

So here's the tea ☕ — the depth of the TX FIFO is a synthesis configuration parameter of the SPI IP. Translation: it's baked in at synthesis time, not something you can just peek at from a register like "hi bestie what's your size".

But!! The FIFO threshold register is sized so that its maximum value can be the FIFO size - 1. That's the loophole 🔥 And that's literally what gets used to detect the size of the FIFO. Clever, right? The register's ceiling is basically a little breadcrumb trail back to the real answer. Obsessed honestly 💖

👑 SEE ALSO 👑

Kernel file ./drivers/spi/spi-axiado.c, plus the whole friend group:

That's the whole page bestie — go forth and detect some FIFO depths 💜✨

This iconic little entry lives in ./drivers/spi and is dated October 2026, per the footer of the original page. Mwah, bye! 🍓🧚
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