usb_decode_ctrl(9)

💖 NAME 💖

okay so you're looking at usb_decode_ctrl(9) from the Kernel API Manual, and the name is literally usb_decode_ctrl — it returns human readable representation of control request. that's the whole main character energy of this function ✨.

✨ SYNOPSIS ✨

       const char * usb_decode_ctrl (char *str , size_t size , __u8
       bRequestType , __u8 bRequest , __u16 wValue , __u16 wIndex , __u16
       wLength );

🎀 ARGUMENTS 🎀

• str — the buffer where the human-readable representation of the control request goes. This buffer should have about 200 bytes, so like… give it room to glow 💅.
• size — size of the str buffer. yes bestie, it needs to know how much space it has 🫶.
• bRequestType — matches the USB bmRequestType field 🌸.
• bRequest — matches the USB bRequest field 🦋.
• wValue — matches the USB wValue field (CPU byte order) ⭐.
• wIndex — matches the USB wIndex field (CPU byte order) 💜.
• wLength — matches the USB wLength field (CPU byte order) 🔥.

🌈 DESCRIPTION 🌈

So the function returns a decoded, formatted and human-readable description of a control request packet. It's giving "translator bestie" realness 💖.

The usage scenario for this is for tracepoints, so the function as a return uses the same value as in the parameters. This approach allows the function to be used in TP_printk ✨.

⚠️ Important: wValue, wIndex, wLength parameters before invoking this function should be processed by le16_to_cpu macro. no cap, do that first or the vibe check fails 😭.

🔍 SEE ALSO 🔍

• Kernel file ./drivers/usb/common/debug.c 👑

that's a wrap, bestie 🎀 source: ./drivers/usb/common; date: October 2026; manual page: usb_decode_ctrl(9). byeee 🫶