STRUCT PCH_UDC_REQUEST(9)

📦 version 7.3.1, in nixpkgs unstable

💅 struct pch_udc_request(9)

okay so bestie, welcome to the Kernel API Manual (section 9, the good section 💖) — today's main character is struct pch_udc_request, the structure holding a PCH USB device request packet. yes it's a struct. yes it's iconic. let's get into it ✨

🎀 SYNOPSIS 🎀

copy this exactly, do not improvise, i'm watching 👀

struct pch_udc_request {
    struct usb_request              req;
    dma_addr_t td_data_phys;
    struct pch_udc_data_dma_desc    *td_data;
    struct pch_udc_data_dma_desc    *td_data_last;
    struct list_head                queue;
    unsigned dma_going:1, dma_done:1;
    unsigned chain_len;
 };

🌸 Members 🌸

okay here's the cast, each one gets their moment:

  • req — the embedded ep request. it lives inside the struct, it's nested, it's cozy 🫶
  • td_data_phys — the phys. address. that's it, that's the whole vibe.
  • td_data — first dma desc. of chain. the opening act ⭐
  • td_data_last — last dma desc. of chain. the finale, the closing number 💅
  • queue — the associated queue. it's giving "you're in my contacts list" energy.
  • dma_going — DMA in progress for request. it's happening, bestie, it's literally happening right now 🔥
  • dma_done — DMA completed for request. we ate and left no crumbs ✨
  • chain_len — chain length. how long is the chain? this long. 📏
ngl dma_going and dma_done are bitfields (:1 each) up in the unsigned declaration, so they're squished in together — that's the code, not me being weird, i promise 🙈

🦋 SEE ALSO 🦋

the whole extended universe, no cap. it all lives in the kernel file ./drivers/usb/gadget/udc/pch_udc.c — start there, then fall down this rabbit hole 🌈

the structs first, they're the popular kids:

  • struct pch_udc_data_dma_desc(9)
  • struct pch_udc_stp_dma_desc(9)
  • struct pch_udc_cfg_data(9)
  • struct pch_udc_ep(9)
  • struct pch_vbus_gpio_data(9)
  • struct pch_udc_dev(9)

and then the function cinematic universe, deep breath, here we go:

and that's the page, bestie 🧚 no cap, you're now officially a struct pch_udc_request girlie. slay 💜

🌸 cute lil sign-off: this one's filed under ./drivers/usb/gadget/udc, dated October 2026, and yes it's still struct pch_udc_request(9) — the icon, the legend, the moment. bye pookie 🎀💖
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