gserial_connect(9)

💖 gserial_connect(9) 💖 — Kernel API Manual

okay bestie, welcome to the Kernel API Manual page for gserial_connect(9) — the little function that tells the TTY I/O glue your USB link is alive and ready to slay ✨

🌸 NAME 🌸

gserial_connect — notify the TTY I/O glue that the USB link is active 💅

🌈 SYNOPSIS 🌈

int gserial_connect (struct gserial *gser , u8 port_num );

🎀 ARGUMENTS 🎀

• gser — the function, already set up with endpoints and descriptors 🫶
• port_num — which port is active 👑

🦋 CONTEXT 🦋

any (usually from irq) — so yeah, it can run in any context, and usually it's coming from an interrupt 😭

💜 DESCRIPTION 💜

Okay so this is the one that activates the endpoints and lets the TTY layer know the connection is active, kind of like “carrier detect” but make it USB ✨. It won't necessarily start the I/O queues; if no task is holding the TTY open, there would be no point anyway. But the endpoints will get activated so the USB host can perform I/O, subject to basic USB hardware flow control 🎀.

Before you call this, caller, you need to have set up the endpoints and the USB function in dev, plus the appropriate (speed-specific) endpoint descriptors. You also need to have allocated port_num by calling gserial_alloc_line 🫶.

It returns a negative errno or zero. On success, ep->driver_data will be overwritten — lowkey important, bestie 💅.

🌟 SEE ALSO 🌟

Kernel file ./drivers/usb/gadget/function/u_serial.c, plus gs_start_io(9) and gserial_disconnect(9) 🦋

xoxo 💋 source/version: ./drivers/usb/gadget/function; date: October 2026 — that's the gserial_connect(9) page, bestie! byeee!