dwc2_check_...ic_bandwidth(9)

💅 dwc2_check_periodic_bandwidth(9) — the Kernel API Manual glow-up ✨

okay so bestie, welcome to the Linux kernel API manual, DWC2 edition 🎀 this one's a function page from ./drivers/usb/dwc2, and honestly it's doing exactly what it says on the tin. let's get into it 🦋

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🌸 NAME 🌸

dwc2_check_periodic_bandwidth — lowkey does a vibe check on the periodic schedule to make sure there's actually enough bandwidth for the QH you're trying to slide in there 💖

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✨ SYNOPSIS ✨

int dwc2_check_periodic_bandwidth (struct dwc2_hsotg *hsotg , struct dwc2_qh *qh );

like yes, that's the whole signature, no cap 🫶

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🧚 ARGUMENTS 🧚

• hsotg — the HCD state structure for the DWC OTG controller. it's giving main character energy, it's the whole controller's state bestie 💅
• qh — the QH that's carrying the periodic bandwidth you need. this one's the diva asking for space on the schedule 👑

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⭐ RETURN ⭐

Returns 0 if it all works out (slay ✨), otherwise a negative error code — so if you get a negative back, that's your sign the bandwidth check did not eat 😭

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🌈 DESCRIPTION 🌈

okay so for simplicity, this calculation assumes that all the transfers in the periodic schedule may occur in the same (micro)frame. that's the whole assumption, fr fr — it keeps the math from becoming a whole situation 💀

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🦋 SEE ALSO 🦋

the source lives in the kernel file ./drivers/usb/dwc2/hcd_queue.c — go read it, iykyk 🍓

and here's the full friend group, no one left out 🫶

• dwc2_periodic_channel_available(9)
• pmap_schedule(9)
• pmap_unschedule(9)
• dwc2_get_ls_map(9)
• dwc2_qh_print(9)
• dwc2_qh_schedule_print(9)
• dwc2_ls_pmap_schedule(9)
• dwc2_ls_pmap_unschedule(9)
• dwc2_hs_pmap_schedule(9)
• dwc2_hs_pmap_unschedule(9)
• dwc2_uframe_schedule_split(9)
• dwc2_uframe_schedule_hs(9)
• dwc2_uframe_schedule_ls(9)
• dwc2_uframe_schedule(9)
• dwc2_uframe_unschedule(9)
• dwc2_pick_first_frame(9)
• dwc2_do_reserve(9)
• dwc2_do_unreserve(9)
• dwc2_unreserve_timer_fn(9)
• dwc2_check_max_xfer_size(9)
• dwc2_schedule_periodic(9)
• dwc2_deschedule_periodic(9)
• dwc2_wait_timer_fn(9)
• dwc2_qh_init(9)
• dwc2_hcd_qh_create(9)
• dwc2_hcd_qh_free(9)
• dwc2_hcd_qh_add(9)
• dwc2_hcd_qh_unlink(9)
• dwc2_next_for_periodic_split(9)
• dwc2_next_periodic_start(9)
• dwc2_hcd_qtd_init(9)
• dwc2_hcd_qtd_add(9)

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💜 reminder bestie: this page is from the ./drivers/usb/dwc2 corner of the kernel, and it's the October 2026 edition of the Kernel API Manual's dwc2_check_...ic_bandwidth(9) page. go off, read the source, and may your bandwidth always be sufficient 🎀✨🔥