OpenIPC AI teamandGitHub
f86ea4f4a6
The OTG profile could not see USB devices in host mode. On a board with a UVC webcam on the USB tail, `lsusb` showed only the two root hubs, while the same board running a plain lite image enumerated the webcam normally. The controller was in the host role and the host controller was running -- mode file "host", xhci-hcd bound, USBCMD 0x5, PORTSC1 port-power set -- and the port still never reported a connect (PORTSC1 0x00000280, CCS clear). dr_mode = "otg" makes dwc3_core_init() program GCTL.PRTCAPDIR = OTG(3), and dwc3_core_init_mode() registers xhci-hcd on top of that. This 4.9 dwc3 has no working OTG role-detection block, so xHCI probes, resets the controller and brings up its root hubs while the core is in a role it cannot drive. The port is then dead for the life of that probe. S72usbmode's `usb-mode host` did not repair it and could not: writing the debugfs mode file reaches dwc3_set_mode(), which flips GCTL.PRTCAPDIR and nothing else, leaving the already-probed xHCI with the port state machine it built in OTG. It also skipped the bind, because xhci-hcd was already bound. Fix it where the ordering is: patch dwc3_core_init() to program PRTCAPDIR = HOST for the OTG case, so xHCI probes into a role the core can drive. dwc3_gadget_init() only registers a UDC and does not care, and `usb-mode device` re-aims the controller itself when it takes the port. usb-mode's host path also learns to re-probe an xHCI that was bound in some other role, which is what makes a newer rootfs recover on an older kernel.
192 lines
6.6 KiB
Bash
Executable File
192 lines
6.6 KiB
Bash
Executable File
#!/bin/sh
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#
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# Switch the single DWC3 controller between USB host and USB device roles.
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#
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# host - xHCI drives the port. This is what the usbcam second-camera path
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# needs (majestic consuming a USB webcam).
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# device - the UVC gadget drives the port, so a PC sees this camera as a
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# webcam.
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#
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# The two are mutually exclusive: xHCI HCSPARAMS1 reports MaxPorts = 1, so
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# there is one port and one role at a time. Switching does not need a reboot.
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#
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# Why this is more than one echo: dwc3_set_mode() (drivers/usb/dwc3/core.c)
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# only flips GCTL.PRTCAPDIR. It does not stop the host stack or start the
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# gadget stack. Writing the debugfs `mode` file on its own leaves xHCI still
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# bound and its DMA engine still live, pointed at a controller that has been
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# re-aimed underneath it. Unbind first, then flip, then bring the other side
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# up.
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set -e
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STATE=/etc/usbmode
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GADGET=/sys/kernel/config/usb_gadget/uvc0
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die() { echo "usb-mode: $*" >&2; exit 1; }
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dwc3_mode_file() {
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for f in /sys/kernel/debug/*.dwc3/mode; do
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[ -e "$f" ] && { echo "$f"; return 0; }
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done
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return 1
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}
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xhci_device() {
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for d in /sys/bus/platform/drivers/xhci-hcd/*.auto; do
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[ -e "$d" ] && { basename "$d"; return 0; }
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done
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# Not currently bound; fall back to the device that exists on the bus.
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for d in /sys/bus/platform/devices/xhci-hcd.*.auto; do
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[ -e "$d" ] && { basename "$d"; return 0; }
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done
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return 1
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}
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udc_name() {
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for u in /sys/class/udc/*; do
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[ -e "$u" ] && { basename "$u"; return 0; }
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done
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return 1
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}
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need_debugfs() {
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mountpoint -q /sys/kernel/debug 2>/dev/null ||
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mount -t debugfs none /sys/kernel/debug
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MODE_FILE=$(dwc3_mode_file) ||
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die "no dwc3 mode file; is CONFIG_USB_DWC3_DUAL_ROLE enabled and debugfs mounted?"
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}
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teardown_gadget() {
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[ -d "$GADGET" ] || return 0
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# Unbind from the UDC first: this drops the D+ pullup so the host sees a
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# disconnect rather than a device that stops answering.
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if [ -e "$GADGET/UDC" ] && [ -s "$GADGET/UDC" ]; then
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echo "" > "$GADGET/UDC" 2>/dev/null || true
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fi
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# configfs rmdir is strict about ordering: links before the things they
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# point at, leaves before their parents. ENOTEMPTY here means something
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# below was missed.
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rm -f "$GADGET/configs/c.1/uvc.0"
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F="$GADGET/functions/uvc.0"
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rm -f "$F/control/class/fs/h" "$F/control/class/ss/h"
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rm -f "$F/streaming/class/fs/h" "$F/streaming/class/hs/h" "$F/streaming/class/ss/h"
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# uvc-gadget-setup composes whichever single format majestic is set to, so
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# tear down both possibilities: only one of them exists on any given boot.
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rm -f "$F/streaming/header/h/f"
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rmdir "$F/streaming/header/h" 2>/dev/null || true
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rmdir "$F/streaming/mjpeg/m/f" 2>/dev/null || true
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rmdir "$F/streaming/mjpeg/m" 2>/dev/null || true
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rmdir "$F/streaming/framebased/h/f" 2>/dev/null || true
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rmdir "$F/streaming/framebased/h" 2>/dev/null || true
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rmdir "$F/control/header/h" 2>/dev/null || true
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# EBUSY here means a userspace process still holds the gadget's
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# /dev/videoN open -- almost always majestic. Stop it first.
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if ! rmdir "$F" 2>/dev/null; then
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die "cannot remove uvc.0 (EBUSY?) -- is majestic still holding /dev/video*? stop it first"
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fi
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rmdir "$GADGET/configs/c.1/strings/0x409" 2>/dev/null || true
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rmdir "$GADGET/configs/c.1" 2>/dev/null || true
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rmdir "$GADGET/strings/0x409" 2>/dev/null || true
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rmdir "$GADGET" 2>/dev/null || true
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}
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to_device() {
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need_debugfs
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if X=$(xhci_device) && [ -e "/sys/bus/platform/drivers/xhci-hcd/$X" ]; then
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# Unbind only from the host role. Asking xhci_halt() to halt a
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# controller whose GCTL.PRTCAPDIR is not HOST means halting a host
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# that was never really running, and it times out:
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# xhci-hcd.0.auto: Host not halted after 16000 microseconds.
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# xhci-hcd.0.auto: Host controller not halted, aborting reset.
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# Leaving it un-halted is precisely the live-DMA-engine state this
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# unbind exists to avoid. Since all-patches 0018 the core is already
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# in the host role whenever xHCI is bound, so this flip is a no-op; it
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# stays as the cheap guarantee that the unbind below halts cleanly.
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[ "$(cat "$MODE_FILE")" = host ] || echo host > "$MODE_FILE"
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echo "usb-mode: unbinding host controller $X"
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echo "$X" > /sys/bus/platform/drivers/xhci-hcd/unbind
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fi
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echo device > "$MODE_FILE"
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modprobe configfs 2>/dev/null || true
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modprobe libcomposite 2>/dev/null || true
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modprobe usb_f_uvc 2>/dev/null || true
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mountpoint -q /sys/kernel/config 2>/dev/null ||
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mount -t configfs none /sys/kernel/config
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/usr/bin/uvc-gadget-setup
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UDC=$(udc_name) ||
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die "no UDC registered -- is dr_mode=\"otg\" in the device tree?"
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echo "$UDC" > "$GADGET/UDC"
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echo device > "$STATE"
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echo "usb-mode: device (UVC gadget bound to $UDC)"
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}
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to_host() {
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need_debugfs
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teardown_gadget
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# Remember which role we are leaving: it decides whether an already-bound
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# host stack has to be re-probed. See below.
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was=$(cat "$MODE_FILE")
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echo host > "$MODE_FILE"
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if X=$(xhci_device); then
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if [ ! -e "/sys/bus/platform/drivers/xhci-hcd/$X" ]; then
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echo "usb-mode: rebinding host controller $X"
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echo "$X" > /sys/bus/platform/drivers/xhci-hcd/bind
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elif [ "$was" != host ]; then
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# Bound, but bound while the core was in another role: it
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# probed, reset the controller and brought up its root hubs
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# against a port it was not driving, and it will never report a
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# connect -- the port powers up and stays at CCS = 0, so lsusb
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# shows nothing but the root hubs however many devices are
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# plugged in. Writing MODE_FILE only flips GCTL.PRTCAPDIR; it
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# does not re-initialise a live xHCI. Making it probe again is
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# what actually brings the port up.
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#
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# The kernel now settles the role before registering the host
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# (all-patches 0018), so this cannot trigger on a matching
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# kernel. It is here for a rootfs running on an older one.
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echo "usb-mode: re-probing host controller $X (was $was)"
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echo "$X" > /sys/bus/platform/drivers/xhci-hcd/unbind
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echo "$X" > /sys/bus/platform/drivers/xhci-hcd/bind
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fi
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fi
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echo host > "$STATE"
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echo "usb-mode: host"
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}
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status() {
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need_debugfs
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echo "dwc3 role : $(cat "$MODE_FILE")"
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echo "persisted : $([ -r "$STATE" ] && cat "$STATE" || echo '(unset, defaults to host)')"
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echo "udc : $(udc_name || echo '(none)')"
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echo "xhci bound: $(xhci_device >/dev/null 2>&1 && \
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([ -e "/sys/bus/platform/drivers/xhci-hcd/$(xhci_device)" ] && echo yes || echo no) || echo '(no device)')"
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echo "gadget : $([ -d "$GADGET" ] && echo "composed, UDC='$(cat "$GADGET/UDC" 2>/dev/null)'" || echo 'not composed')"
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}
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case "$1" in
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device) to_device ;;
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host) to_host ;;
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status) status ;;
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*)
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echo "Usage: $0 {host|device|status}"
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exit 1
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;;
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esac
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