usb-host: Replace pre with SplitInfo#5884
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leftger merged 3 commits intoembassy-rs:mainfrom Apr 19, 2026
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Pull request overview
This PR updates the USB host stack to replace the legacy pre: bool (“emit PRE packet”) plumbing with an extensible SplitInfo type, allowing host/HAL drivers and class drivers to carry hub/port routing metadata needed for split transactions and PRE-based routing.
Changes:
- Introduce
SplitInfoinembassy-usb-driverand updateUsbHostDriver::alloc_channel/UsbChannel::retarget_channelto takeOption<SplitInfo>instead ofbool. - Thread
split: Option<SplitInfo>through enumeration (EnumerationInfo) and host-class drivers (HID/CDC ACM/GIP/UAC/KBD/HUB). - Update HAL host driver implementations (STM32 OTG/USBFS, RP2040, Synopsys OTG) to the new signatures, mapping split info to legacy PRE where applicable.
Reviewed changes
Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| embassy-usb-driver/src/host.rs | Adds SplitInfo and updates host/channel traits to accept Option<SplitInfo>. |
| embassy-usb-host/src/lib.rs | Updates root-device enumeration to pass None for split routing. |
| embassy-usb-host/src/handler.rs | Replaces ls_over_fs with split: Option<SplitInfo> in EnumerationInfo. |
| embassy-usb-host/src/control.rs | Threads split through enumerate_device() and retarget_channel() calls. |
| embassy-usb-host/src/class/hub.rs | Uses split during hub/device enumeration and when allocating channels behind hubs. |
| embassy-usb-host/src/class/kbd.rs | Passes enum_info.split into channel allocation. |
| embassy-usb-host/src/class/uac/mod.rs | Passes enum_info.split into channel allocation for control/iso endpoints. |
| embassy-usb-host/src/class/hid.rs | Extends HidHost::new to accept split and uses it for channel allocation. |
| embassy-usb-host/src/class/cdc_acm.rs | Extends CdcAcmHost::new to accept split and uses it for channel allocation. |
| embassy-usb-host/src/class/gip.rs | Extends GipHost::new to accept split and uses it for channel allocation. |
| embassy-usb-synopsys-otg/src/host.rs | Updates host driver/channel method signatures to accept split. |
| embassy-stm32/src/usb/usb_host.rs | Updates STM32 USBFS host driver/channel signatures and call sites to accept split. |
| embassy-stm32/src/usb/otg.rs | Updates STM32 OTG wrapper to forward split through. |
| embassy-rp/src/usb/host.rs | Adds split_to_pre() and maps Option<SplitInfo> down to the RP2040 PRE flag. |
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bender run |
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Apologies @bugadani . I think I created some merge conflicts in the process of merging in previous PRs. When you have time could you help me resolve them? This PR looks good honestly. |
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…-rs#5897 review comments - Add SplitInfo/SplitSpeed types from upstream (embassy-rs#5884 usb-host-split-info) - Replace pre: bool with split: Option<SplitInfo> in alloc_channel - Add retarget_channel to UsbChannel trait and all implementations - Move RequestType/SetupPacket from embassy-usb-driver to embassy-usb-host/control.rs with new struct-based API (replacing bitflags approach) per review comment - Change control_in/control_out to take &[u8; 8] instead of &SetupPacket - Remove where T: channel::IsControl constraint from set_timeout - Fix UsbChannel doc link (was broken by super::UsbChannel path) - Add Babble and DataToggleError variants to ChannelError (requested by reviewers) - Update NAK handling docs: bulk retries indefinitely (cancel via drop), control uses configurable timeout via set_timeout - Add data toggle documentation to UsbChannel - Update all class drivers (hub, hid, cdc_acm, uac) to use new API - Add enumerate_device to ControlChannelExt, simplify UsbHost::enumerate
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This PR ensures future compatibility with high-speed USB hubs in the host driver. Additionally, enumeration now returns EnumerationInfo (duh) and class constructors consistently take EnumerationInfo to better support connecting through HUBs.