STRUCT CDNS2_RING(9)

✨ struct cdns2_ring(9) ✨

okay so bestie, welcome to the Kernel API Manual 💖 — this is the page for struct cdns2_ring, aka the transfer ring representation. yes, THE ring. the main character of the USB gadget show 💅

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🌸 NAME 🌸

struct cdns2_ring — transfer ring representation.

like, it is the ring. that's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

struct cdns2_ring {
    struct cdns2_trb *trbs;
    dma_addr_t dma;
    int free_trbs;
    u8 pcs;
    u8 ccs;
    int enqueue;
    int dequeue;
 };

not me dropping the whole struct definition like it's a fit pic 📸 — every single field is iconic, let's go through them one by one 👑

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💜 Members 💜

• trbs — pointer to transfer ring. literally where the transfer ring lives, no cap 📍
• dma — dma address of transfer ring. the DMA address, bestie — because this ring gets accessed by the hardware too, iykyk 🧚
• free_trbs — number of free TRBs in transfer ring. how much room is left in there, fr fr 🫶
• pcs — producer cycle state. the producer cycle state, periodt ✨
• ccs — consumer cycle state. and this one? consumer cycle state. they're a matching set, obsessed 💅
• enqueue — enqueue index in transfer ring. where the next thing goes in, lowkey important 📥
• dequeue — dequeue index in transfer ring. where things come out. balance. harmony. 🌈

bestie note: nothing here is dangerous or deprecated — it's just a struct doing its little struct thing 🎀

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🔥 SEE ALSO 🔥

kernel file ./drivers/usb/gadget/udc/cdns2/cdns2-gadget.h — that's the source of truth, go read it, it ate 💯

and the whole cdns2 fam, all in one group chat:

• struct cdns2_ep0_regs(9)
• struct cdns2_epx_base(9)
• struct cdns2_epx_regs(9)
• struct cdns2_interrupt_regs(9)
• struct cdns2_usb_regs(9)
• struct cdns2_adma_regs(9)
• struct cdns2_trb(9)
• struct cdns2_endpoint(9)
• struct cdns2_request(9)
• struct cdns2_device(9)

that's the whole squad, no skips 🫡

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⭐ and that's the page!! brought to you by the fine people at ./drivers/usb/gadget/udc/cdns2, stamped October 2026, and yes it's still struct cdns2_ring(9) at the bottom, iconic from start to finish 💖🦋✨