On Sun, Aug 24, 2025, Janne Grunau wrote: > On Thu, Aug 21, 2025 at 11:25:51PM +0000, Thinh Nguyen wrote: > > On Thu, Aug 21, 2025, Sven Peter wrote: > > > As mad as it sounds, the dwc3 controller present on the Apple M1 must be > > > reset and reinitialized whenever a device is unplugged from the root > > > port or when the PHY mode is changed. > > > > > > This is required for at least the following reasons: > > > > > > - The USB2 D+/D- lines are connected through a stateful eUSB2 repeater > > > which in turn is controlled by a variant of the TI TPS6598x USB PD > > > chip. When the USB PD controller detects a hotplug event it resets > > > the eUSB2 repeater. Afterwards, no new device is recognized before > > > the DWC3 core and PHY are reset as well because the eUSB2 repeater > > > and the PHY/dwc3 block disagree about the current state. > > > > > > - It's possible to completely break the dwc3 controller by switching > > > it to device mode and unplugging the cable at just the wrong time. > > > If this happens dwc3 behaves as if no device is connected. > > > CORESOFTRESET will also never clear after it has been set. The only > > > workaround is to trigger a hard reset of the entire dwc3 core with > > > its external reset line. > > > > > > - Whenever the PHY mode is changed (to e.g. transition to DisplayPort > > > alternate mode or USB4) dwc3 has to be shutdown and reinitialized. > > > Otherwise the Type-C port will not be usable until the entire SoC > > > has been reset. > > > > > > All of this can be easily worked around by respecting transitions to > > > USB_ROLE_NONE and making sure the external reset line is asserted when > > > switching roles. We additionally have to ensure that the PHY is > > > suspended during init. > > > > > > Signed-off-by: Sven Peter <sven@xxxxxxxxxx> > > > --- > > > drivers/usb/dwc3/core.c | 61 +++++++++++++++++++++++++++++++++++++++++++++---- > > > drivers/usb/dwc3/core.h | 3 +++ > > > drivers/usb/dwc3/drd.c | 11 ++++++++- > > > drivers/usb/dwc3/host.c | 3 ++- > > > 4 files changed, 72 insertions(+), 6 deletions(-) > > > > > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > > > index 8002c23a5a02acb8f3e87b2662a53998a4cf4f5c..26aa507a738f001409a97ef563c6561433a1cac5 100644 > > > --- a/drivers/usb/dwc3/core.c > > > +++ b/drivers/usb/dwc3/core.c > > ... > > > > /* > > > * When current_dr_role is not set, there's no role switching. > > > * Only perform GCTL.CoreSoftReset when there's DRD role switching. > > > */ > > > - if (dwc->current_dr_role && ((DWC3_IP_IS(DWC3) || > > > + if (dwc->role_switch_reset_quirk || > > > > Don't override the use of GCTL.CoreSoftReset with this quirk. Not all > > controller versions should use GCTL.CoreSoftReset, the new controller > > version don't even have it. What version is this vendor using? > > It reports DWC31, revision 190A and the unlisted version_types > 0x736f3035 (M1), 0x736f3039 (M1 Pro/Max/Ultra) and 0x736f3130 (M2, M2 > Pro/Max/Ultra). > Thanks for the info. This version should not be using GCTL.CoreSoftReset. BR, Thinh
