When aborting a Transfer Descriptor (TD), the xHCI driver updates the device dequeue pointer by converting the virtual enqueue TRB pointer into a DMA address.
Previously, the code OR-ed the ring's Dequeue Cycle State (DCS) bit into the virtual TRB pointer before passing it to xhci_trb_virt_to_dma(). This produced an unaligned virtual address (e.g. ending in 0x...1). Inside xhci_trb_virt_to_dma(), the offset calculation: segment_offset = trb - seg->trbs; operated on this unaligned pointer, resulting in an incorrect TRB index. In wraparound cases, this caused the bounds check to fail and the function to return 0. As a result, a SET_DEQ_PTR command was issued with a DMA address of 0x0, leading to controller hangs and transfer timeouts, most commonly when aborting TDs near the end of a ring segment (e.g. index 63). Fix this by translating the aligned virtual TRB pointer to a DMA address first, and only then applying the DCS bit to the resulting physical address. Signed-off-by: ANANDHAKRISHNAN S <[email protected]> --- Changes in v4: - Moved the changelog below the '---' marker to prevent it from being included in the permanent git history. Changes in v3: - Simplified the DMA address calculation by removing the redundant bit(0) mask (& ~0x1ULL), as XHCI guarantees the address is already aligned. Changes in v2: - Apply the same fix to reset_ep() - Simplify cycle bit handling to a single mask operation drivers/usb/host/xhci-ring.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 34eb4536f0e..6f5c4ec97b6 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -523,9 +523,8 @@ static void reset_ep(struct usb_device *udev, int ep_index) field = le32_to_cpu(event->trans_event.flags); BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id); xhci_acknowledge_event(ctrl); - - addr = xhci_trb_virt_to_dma(ring->enq_seg, - (void *)((uintptr_t)ring->enqueue | ring->cycle_state)); + addr = xhci_trb_virt_to_dma(ring->enq_seg, ring->enqueue) | + ring->cycle_state; xhci_queue_command(ctrl, addr, udev->slot_id, ep_index, TRB_SET_DEQ); event = xhci_wait_for_event(ctrl, TRB_COMPLETION); if (!event) @@ -582,9 +581,8 @@ static void abort_td(struct usb_device *udev, int ep_index) TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags)) != udev->slot_id || (comp != COMP_SUCCESS && comp != COMP_CTX_STATE)); xhci_acknowledge_event(ctrl); - - addr = xhci_trb_virt_to_dma(ring->enq_seg, - (void *)((uintptr_t)ring->enqueue | ring->cycle_state)); + addr = xhci_trb_virt_to_dma(ring->enq_seg, ring->enqueue) | + ring->cycle_state; xhci_queue_command(ctrl, addr, udev->slot_id, ep_index, TRB_SET_DEQ); event = xhci_wait_for_event(ctrl, TRB_COMPLETION); if (!event) -- 2.25.1
