On Wed, Oct 07, 2026 at 12:58:33AM +0900, khaliforce wrote: > The generic OHCI and EHCI drivers provide remove callbacks, but do > not set DM_FLAG_ACTIVE_DMA. Their controllers can remain active > when U-Boot hands control to the operating system. > > An active controller may continue DMA after the operating system > starts reusing U-Boot memory. In particular, OHCI may continue > accessing its HCCA. > > Set DM_FLAG_ACTIVE_DMA on both drivers so their existing remove > callbacks stop the controllers during OS preparation. > > Signed-off-by: khaliforce <[email protected]> > --- > Changes in v2: > - Use DM_FLAG_ACTIVE_DMA as suggested by Neil Armstrong. > > Retested on MangoPi MQ Pro with the downstream D1 port based on > U-Boot v2026.10 and Linux 6.1: > - Read a 64 GB FAT32 USB device in U-Boot. > - Verified a 4096-byte read against Linux using CRC32. > - Booted Linux without running "usb stop". > - Confirmed USB reads, Wi-Fi and SSH after the handoff. > - Observed no panic, Bad page or failed services. > > Standalone builds pass for RISC-V64, ARM64 and ARM32 on upstream > main. RISC-V64 QEMU boots. Checkpatch reports no errors or warnings. > > drivers/usb/host/ehci-generic.c | 2 +- > drivers/usb/host/ohci-generic.c | 3 ++- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/host/ehci-generic.c b/drivers/usb/host/ehci-generic.c > index 1ae3619ce25..57f1bcbd9c0 100644 > --- a/drivers/usb/host/ehci-generic.c > +++ b/drivers/usb/host/ehci-generic.c > @@ -167,5 +167,5 @@ U_BOOT_DRIVER(ehci_generic) = { > .remove = ehci_usb_remove, > .ops = &ehci_usb_ops, > .priv_auto = sizeof(struct generic_ehci), > - .flags = DM_FLAG_ALLOC_PRIV_DMA, > + .flags = DM_FLAG_ALLOC_PRIV_DMA | DM_FLAG_ACTIVE_DMA, > }; > diff --git a/drivers/usb/host/ohci-generic.c b/drivers/usb/host/ohci-generic.c > index cc44226f5e0..7493750f8d1 100644 > --- a/drivers/usb/host/ohci-generic.c > +++ b/drivers/usb/host/ohci-generic.c > @@ -110,5 +110,6 @@ U_BOOT_DRIVER(ohci_generic) = { > .remove = ohci_usb_remove, > .ops = &ohci_usb_ops, > .priv_auto = sizeof(struct generic_ohci), > - .flags = DM_FLAG_ALLOC_PRIV_DMA, > + /* Stop HCCA DMA before Linux reuses the controller memory. */ > + .flags = DM_FLAG_ALLOC_PRIV_DMA | DM_FLAG_ACTIVE_DMA, > };
Ah. Perhaps this is also what Romain needs for fixing the problem they see on an Apple platform, and would be more palatable to Marek to apply generally to USB host drivers (and switch the ones that use DM_FLAG_OS_PREPARE today?) ? -- Tom
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