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Differential D51759

libusb: implement zlp flag in libusb transfer
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Authored by aokblast on Aug 6 2025, 12:58 PM.
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adrian
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USB
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rGd84b639a684e: libusb: implement zlp flag in libusb transfer
Summary

The USB protocol defines a Zero-Length Packet (ZLP) to signal the end of
a transfer when the data size is an exact multiple of the Maximum Packet
Size (MPS). Without a ZLP in such cases, the device may not be able to
determine that the transfer has completed.

This flag is added to libusb to allow the user send a ZLP in the end
of libusb_xfer.

Diff Detail

Repository
rG FreeBSD src repository
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Lint Passed
Unit
No Test Coverage
Build Status
Buildable 66339
Build 63222: arc lint + arc unit

Event Timeline

aokblast created this revision.Aug 6 2025, 12:58 PM
Herald added a subscriber: imp. · View Herald TranscriptAug 6 2025, 12:58 PM
aokblast requested review of this revision.Aug 6 2025, 12:58 PM
Harbormaster completed remote builds in B66010: Diff 159849.Aug 6 2025, 12:59 PM
aokblast updated this revision to Diff 160029.Aug 8 2025, 7:33 AM

Send packet only the multiple of packet

Harbormaster completed remote builds in B66093: Diff 160029.Aug 8 2025, 7:33 AM
aokblast updated this revision to Diff 160030.Aug 8 2025, 7:58 AM

defer zlp check until we can find the xfer

Harbormaster completed remote builds in B66094: Diff 160030.Aug 8 2025, 7:58 AM
lwhsu added a subscriber: lwhsu.Aug 18 2025, 6:18 AM
lwhsu added inline comments.
lib/libusb/libusb10.c
1628

should we use libusb20_tr_get_max_packet_length() or libusb20_tr_get_max_total_length()?

aokblast updated this revision to Diff 160585.Aug 19 2025, 11:18 AM

Get correct MPS

Harbormaster completed remote builds in B66339: Diff 160585.Aug 19 2025, 11:18 AM
aokblast added a comment.Aug 29 2025, 6:38 AM

This implemented is problematic since the correct way is to append a zero size TRB in TD instead of creating new TD. However, I think I am unable to make it work before 15.0 release. Therefore, I will modify it to at least we won't break any ABI for 15 if we want to merge later.

aokblast updated this revision to Diff 179613.Jun 11 2026, 3:45 PM

Use the correct impl

Harbormaster completed remote builds in B73828: Diff 179613.Jun 11 2026, 3:45 PM
adrian accepted this revision.Jun 18 2026, 5:11 AM
adrian added a reviewer: USB.
adrian added a project: USB.
This revision is now accepted and ready to land.Jun 18 2026, 5:11 AM
Closed by commit rGd84b639a684e: libusb: implement zlp flag in libusb transfer (authored by aokblast). · Explain WhyJun 22 2026, 1:37 PM
This revision was automatically updated to reflect the committed changes.
aokblast added a commit: rGd84b639a684e: libusb: implement zlp flag in libusb transfer.

Revision Contents
Changeset List

PathSize
lib/
libusb/
1 line
24 lines

Diff 160585

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lib/libusb/libusb.h

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lib/libusb/libusb10.c

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