Date: Fri, 22 May 2026 07:41:20 +0000 From: ShengYi Hung <aokblast@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 28d85db46b48 - main - xhci: Do not drop and add bits in xhci Message-ID: <6a1008a0.3f79c.1d455f29@gitrepo.freebsd.org>
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The branch main has been updated by aokblast: URL: https://cgit.FreeBSD.org/src/commit/?id=28d85db46b484589e2ee74cf4b270db066821de1 commit 28d85db46b484589e2ee74cf4b270db066821de1 Author: ShengYi Hung <aokblast@FreeBSD.org> AuthorDate: 2026-05-21 12:49:42 +0000 Commit: ShengYi Hung <aokblast@FreeBSD.org> CommitDate: 2026-05-22 07:41:07 +0000 xhci: Do not drop and add bits in xhci Drop and Add bits reset the data toggle for high-speed devices in XHCI. The toggle bit represents the sequence number in USB 2.0 transfers. However, a device can only recognize that the toggle bit has been reset while in the HALT state. As a result, the host and device toggle values may become mismatched, causing xHCI to reject the packet. This issue was observed while testing the EZ-USB FX2 device. The transfer may then return to the original value after a bi-directional TD because the toggle field is only one bit wide. This explains the reson that we can only receive packets bi-transfer in some case. Therefore, we do not reset the toggle bit here. Reviewed by: adrian MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D57146 --- sys/dev/usb/controller/xhci.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/sys/dev/usb/controller/xhci.c b/sys/dev/usb/controller/xhci.c index 3dad0985b39d..b522c5fdc5a3 100644 --- a/sys/dev/usb/controller/xhci.c +++ b/sys/dev/usb/controller/xhci.c @@ -3898,10 +3898,8 @@ xhci_configure_reset_endpoint(struct usb_xfer *xfer) */ switch (xhci_get_endpoint_state(udev, epno)) { case XHCI_EPCTX_0_EPSTATE_DISABLED: - drop = 0; - break; case XHCI_EPCTX_0_EPSTATE_STOPPED: - drop = 1; + drop = 0; break; case XHCI_EPCTX_0_EPSTATE_HALTED: err = xhci_cmd_reset_ep(sc, 0, epno, index); @@ -3910,9 +3908,15 @@ xhci_configure_reset_endpoint(struct usb_xfer *xfer) DPRINTF("Could not reset endpoint %u\n", epno); break; default: - drop = 1; + /* + * xHCI spec 4.6.8: + * The Drop and Add operation resets the toggle bit, which can + * cause a toggle mismatch between the device and host. As a + * result, xHCI may refuse to receive or process the packet. + */ err = xhci_cmd_stop_ep(sc, 0, epno, index); - if (err != 0) + drop = (err != 0); + if (drop) DPRINTF("Could not stop endpoint %u\n", epno); break; }home | help
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