ENUM EM28XX_AMUX(9)

💅 enum em28xx_amux(9) — the Kernel API Manual, but make it cute

okay so bestie, welcome to the glow-up of a manpage from the Kernel API Manual ✨ this one's all about enum em28xx_amux, and it's literally the vibe check for which audio input your em28xx device is using 🎀

---

🌸 NAME

enum em28xx_amux — describes the type of audio input used by em28xx 💖

---

✨ SYNOPSIS

enum em28xx_amux {
    EM28XX_AMUX_UNUSED ,
    EM28XX_AMUX_VIDEO ,
    EM28XX_AMUX_LINE_IN ,
    EM28XX_AMUX_VIDEO2 ,
    EM28XX_AMUX_PHONE ,
    EM28XX_AMUX_MIC ,
    EM28XX_AMUX_CD ,
    EM28XX_AMUX_AUX ,
    EM28XX_AMUX_PCM_OUT

};

---

🫶 Constants

• EM28XX_AMUX_UNUSED — bestie this one is only used on the em28xx dev->map field, just to mark an entry as unused. It's the "this seat is saved" of constants 💅
• EM28XX_AMUX_VIDEO — on devices without AC97, this is the only value that's currently allowed. On devices with AC97, it corresponds to the AC97 mixer "Video" control 🎥
• EM28XX_AMUX_LINE_IN — only for devices with AC97. Corresponds to AC97 mixer "Line In" 🎧
• EM28XX_AMUX_VIDEO2 — only for devices with AC97. It means em28xx should use "Line In" and AC97 should use the "Video" mixer control. yes bestie, a crossover episode 🔥
• EM28XX_AMUX_PHONE — only for devices with AC97. Corresponds to AC97 mixer "Phone" 📞
• EM28XX_AMUX_MIC — only for devices with AC97. Corresponds to AC97 mixer "Mic" 🎤
• EM28XX_AMUX_CD — only for devices with AC97. Corresponds to AC97 mixer "CD" 💿
• EM28XX_AMUX_AUX — only for devices with AC97. Corresponds to AC97 mixer "Aux" 🔌
• EM28XX_AMUX_PCM_OUT — only for devices with AC97. Corresponds to AC97 mixer "PCM out" 🔊

---

💜 Description

ngl, the em28xx chip itself has only two audio inputs: tuner and line in. And on almost all devices, only the tuner input is used 🦋

But!! on most devices, an auxiliary AC97 codec device gets used too, usually connected to the em28xx tuner input — except for EM28XX_AMUX_LINE_IN, that one's the outlier main character 👑

The AC97 device typically has several different inputs and outputs. The exact number and description depends on their model 🌈

And yes, it is possible to AC97 to mixer more than one different entries at the same time, via the alsa mux. multi-tasking icon behaviour, periodt ✨

---

👀 SEE ALSO

• Kernel file ./drivers/media/usb/em28xx/em28xx.h struct em28xx_usb_bufs(9), struct em28xx_usb_ctl(9), struct em28xx_fmt(9), struct em28xx_buffer(9)

---

ok that's the whole page bestie, every constant and every caveat is in there, no cap 💀 don't come for me if you skip the AC97-only ones, they're labeled for a reason 🙈

so this lil masterclass comes to you courtesy of ./drivers/media/usb/em28xx, dated October 2026, and it's filed under enum em28xx_amux(9) in the Kernel API Manual — mwah, slay, bye 🧚💖