pxa_udc_vbus_draw(9)

💅 pxa_udc_vbus_draw(9) — the kernel API manual, but make it make sense

okay so bestie, welcome to the glow-up edition of pxa_udc_vbus_draw(9), straight out of the Kernel API Manual ✨ this one is short and sweet — no cap, it's literally one job — so let's get into it 🫶

---

✨ NAME ✨

pxa_udc_vbus_draw — the function that gets called by the gadget driver once SET_CONFIGURATION has completed, so everybody knows how much juice we're allowed to pull 💖

---

🌸 SYNOPSIS 🌸

int pxa_udc_vbus_draw (struct usb_gadget *_gadget , unsigned mA );

---

🎀 ARGUMENTS 🎀

• _gadget — the usb gadget in question, main character of the USB world 👑
• mA — the current being drawn, in milliamps. yes, actual numbers, we love a measurable vibe ⚡

---

🦋 CONTEXT 🦋

task context — and heads up bestie, it might sleep 😴 so do not, I repeat do not, call this from somewhere spicy like an atomic context. she naps and she's allowed to.

---

💜 DESCRIPTION 💜

So the flow is: a USB host picks a configuration, and then this function gets called to let everyone know how much current the device is allowed to draw from the VBus line 🔌✨ that's it, that's the whole job. clean, simple, iconic.

It returns 0, or -EOPNOTSUPP if there is no transceiver handling the udc 💀 (iykyk — that error is basically the kernel saying "bestie, nobody's home").

---

🌈 SEE ALSO 🌈

the whole friend group, fr fr — no skipping, they all get their moment 💅

• ep matching & pio stuff: is_match_usb_pxa(9), find_pxa_ep(9), update_pxa_ep_matches(9), pio_irq_enable(9), pio_irq_disable(9)
• UDCCR mask things: udc_set_mask_UDCCR(9), udc_clear_mask_UDCCR(9), ep_write_UDCCSR(9)
• endpoint helpers: ep_count_bytes_remain(9), ep_is_empty(9), ep_is_full(9), epout_has_pkt(9), set_ep0state(9), ep0_idle(9), inc_ep_stats_reqs(9), inc_ep_stats_bytes(9)
• setup & requests: pxa_ep_setup(9), pxa_eps_setup(9), pxa_ep_alloc_request(9), pxa_ep_free_request(9), ep_add_request(9), ep_del_request(9), req_done(9)
• ending requests: ep_end_out_req(9), ep0_end_out_req(9), ep_end_in_req(9), ep0_end_in_req(9), nuke(9)
• packets & fifos: read_packet(9), write_packet(9), read_fifo(9), write_fifo(9), read_ep0_fifo(9), write_ep0_fifo(9)
• queueing & halting: pxa_ep_queue(9), pxa_ep_dequeue(9), pxa_ep_set_halt(9), pxa_ep_fifo_status(9), pxa_ep_fifo_flush(9), pxa_ep_enable(9), pxa_ep_disable(9), dplus_pullup(9)
• udc core-ish: pxa_udc_get_frame(9), pxa_udc_wakeup(9), should_enable_udc(9), should_disable_udc(9), pxa_udc_pullup(9), pxa_udc_vbus_session(9), pxa_udc_phy_event(9), udc_disable(9), udc_init_data(9), udc_enable(9)
• start & stop: pxa27x_udc_start(9), stop_activity(9), pxa27x_udc_stop(9)
• ep0 handling & reconfig: handle_ep0_ctrl_req(9), handle_ep0(9), handle_ep(9), pxa27x_change_configuration(9), pxa27x_change_interface(9)
• irq squad: irq_udc_suspend(9), irq_udc_resume(9), irq_udc_reconfig(9), irq_udc_reset(9), pxa_udc_irq(9)
• probe / remove / pm: pxa_udc_probe(9), pxa_udc_remove(9), pxa_udc_suspend(9), pxa_udc_resume(9)

also: the kernel file ./drivers/usb/gadget/udc/pxa27x_udc.c is where all of this lives, so that's your source of truth 🧚

---

okay that's the whole page, you ate that 💅💖 this lil' writeup came to you from the kernel files at ./drivers/usb/gadget/udc, dated October 2026 — mwah, go read some source, bestie 🌸✨