[Bug 215890] Regression in 5.18: bcm5974 trackpad causes error: xhci_hcd rejecting DMA map of vmalloc memory

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=215890

Mathias Nyman (mathias.nyman@linux.intel.com) changed:

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                 CC|                            |mathias.nyman@linux.intel.c
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--- Comment #11 from Mathias Nyman (mathias.nyman@linux.intel.com) ---
Could it be that bcm5974 driver just forgot to set the URB_NO_TRANSFER_DMA_MAP
flag in urb transfer_flags?

If the usb driver does the allocation and dma mapping, and sets
urb->transfer_dma
then it should set that flag. Otherwise usbcore will map the DMA address.

Documentation/driver-api/usb/dma.rst:

- URBs have an additional "transfer_dma" field, as well as a transfer_flags
  bit saying if it's valid.  (Control requests also have "setup_dma", but
  drivers must not use it.)

- "usbcore" will map this DMA address, if a DMA-aware driver didn't do
  it first and set ``URB_NO_TRANSFER_DMA_MAP``.  HCDs
  don't manage dma mappings for URBs.

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