read_ep0_fifo(9)

💖 read_ep0_fifo(9) — Kernel API Manual, bestie edition 🎀

okay so picture this: it's the Kernel API Manual, and we're about to talk about read_ep0_fifo. yes that's the whole page title and honestly? iconic. let's get into it ✨

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🌸 NAME 🌸

read_ep0_fifo — literally here to transfer packets from the control endpoint into the usb request. that's the job. that's the whole vibe. 💅

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🦋 SYNOPSIS 🦋

int read_ep0_fifo (struct pxa_ep *ep , struct pxa27x_request *req );

look at her go. two args, one int return, no notes. 🫶

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✨ ARGUMENTS ✨

• ep — the control endpoint, aka the main character of this whole operation 👑
• req — the pxa usb request, where all the bytes are gonna end up 🎀

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💜 DESCRIPTION 💜

okay so this is the special ep0 version of the above read_fifo — like, the limited-edition drop, iykyk. 🌈

what it does: reads as many bytes from the control endpoint as can be read, and stores them into the usb request. and yes, it's limited by the request maximum length — so it's not just gonna keep going forever, it has boundaries, we love a function with boundaries. 💀

Return value time, because this one's a little funky:

• returns 0 if the usb request is only partially filled
• returns 1 if it's fully filled

that's it. that's the whole bit. lowkey elegant ngl 🦋

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⭐ SEE ALSO ⭐

okay bestie, this is a long list, so buckle up — we're going to the function-adjacent. everything here lives in the kernel file ./drivers/usb/gadget/udc/pxa27x_udc.c, and honestly the way this file has this many functions is giving "wrote one file and said periodt". 🔥

• is_match_usb_pxa(9)
• find_pxa_ep(9)
• update_pxa_ep_matches(9)
• pio_irq_enable(9)
• pio_irq_disable(9)
• udc_set_mask_UDCCR(9)
• udc_clear_mask_UDCCR(9)
• ep_write_UDCCSR(9)
• 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)
• 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)
• ep_end_out_req(9)
• ep0_end_out_req(9)
• ep_end_in_req(9)
• ep0_end_in_req(9)
• nuke(9)
• read_packet(9)
• write_packet(9)
• read_fifo(9)
• write_fifo(9)
• write_ep0_fifo(9)
• 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)
• 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_vbus_draw(9)
• pxa_udc_phy_event(9)
• udc_disable(9)
• udc_init_data(9)
• udc_enable(9)
• pxa27x_udc_start(9)
• stop_activity(9)
• pxa27x_udc_stop(9)
• handle_ep0_ctrl_req(9)
• handle_ep0(9)
• handle_ep(9)
• pxa27x_change_configuration(9)
• pxa27x_change_interface(9)
• irq_udc_suspend(9)
• irq_udc_resume(9)
• irq_udc_reconfig(9)
• irq_udc_reset(9)
• pxa_udc_irq(9)
• pxa_udc_probe(9)
• pxa_udc_remove(9)
• pxa_udc_suspend(9)
• pxa_udc_resume(9)

like… 70-something friends. she's social. 💅✨

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and that's the page!! 🫶 this lil baddie lives in ./drivers/usb/gadget/udc, and the version stamp on this whole thing is October 2026 — so jot that down, screenshot it, frame it, whatever feels right. bye bestie, go read some fifos 💖🎀🌸