On 9/26/26 5:35 AM, Romain Beauxis wrote:
Le mer. 16 sept. 2026 à 23:47, Marek Vasut <[email protected]> a
écrit :
On 9/16/26 9:24 PM, Romain Beauxis wrote:
Le sam. 12 sept. 2026 à 22:04, Marek Vasut <[email protected]> a
écrit :
On 9/11/26 10:32 PM, Romain Beauxis wrote:
Neither bootm nor EFI ExitBootServices() stops USB controllers
explicitly. Both only remove devices whose driver sets
DM_FLAG_ACTIVE_DMA or DM_FLAG_OS_PREPARE. xhci-dwc3 sets neither, so a
controller brought up by "usb start", e.g. from preboot for a USB
keyboard, is handed to the OS still running.
Set DM_FLAG_OS_PREPARE so that xhci_dwc3_remove() runs at handoff.
This
is the path "usb stop" already takes: the xHCI is reset, its PHYs are
shut down and its clocks and resets are released. Child devices such
as
hubs, storage and keyboards are removed first, and a controller
already
stopped by "usb stop" is skipped. xhci-pci has done the same since
commit e3bbc1f74e05 ("usb: xhci-pci: Add DM_FLAG_OS_PREPARE flag"), as
have ohci-da8xx and the cdns3 wrappers.
On Apple silicon machines the running controller is user visible:
Linux
does not enumerate a USB device attached to a Type-C port at boot
until
it is unplugged and plugged back in.
boot/bootm.c bootm_final() does call dm_remove_devices_active() , is
that not sufficient to tear the controllers down before booting Linux ?
Any idea how to test this?
Add a printf() into the controller and uclass .remove/.unbind callbacks ?
:)
Ok I can try that but I'm not sure if your question covers a part that's
been untested. What I did confirm:
* Stock u-boot: kernel does not pick up the USB device on boot
* With explicit usb stop: kernel does pick up the USB device on boot
* With proposed patch: kernel does pick up the USB device on boot
Is your question related to a different scenario that has not been covered
yet?
boot/bootm.c bootm_final() does call dm_remove_devices_active() , that
should be enough to shut the controller down. Why is it not enough ?
What does "the USB device" and "pick up" mean here, does the controller
fail to enumerate devices attached to it when Linux boots ? Could the
problem be related to some clock or some such instead ?
