[PATCH 5.10 02/95] xhci: add quirk for host controllers that dont update endpoint DCS

[Greg Kroah-Hartman]

From: Jonathan Bell <jonathan@xxxxxxxxxxxxxxx>

commit 5255660b208aebfdb71d574f3952cf48392f4306 upstream.

Seen on a VLI VL805 PCIe to USB controller. For non-stream endpoints
at least, if the xHC halts on a particular TRB due to an error then
the DCS field in the Out Endpoint Context maintained by the hardware
is not updated with the current cycle state.

Using the quirk XHCI_EP_CTX_BROKEN_DCS and instead fetch the DCS bit
from the TRB that the xHC stopped on.

[ bjorn: rebased to v5.14-rc2 ]

Link: https://github.com/raspberrypi/linux/issues/3060
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jonathan Bell <jonathan@xxxxxxxxxxxxxxx>
Signed-off-by: Bjørn Mork <bjorn@xxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211008092547.3996295-3-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci-pci.c  |    4 +++-
 drivers/usb/host/xhci-ring.c |   26 +++++++++++++++++++++++++-
 drivers/usb/host/xhci.h      |    1 +
 3 files changed, 29 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -276,8 +276,10 @@ static void xhci_pci_quirks(struct devic
 			pdev->device == 0x3432)
 		xhci->quirks |= XHCI_BROKEN_STREAMS;
 
-	if (pdev->vendor == PCI_VENDOR_ID_VIA && pdev->device == 0x3483)
+	if (pdev->vendor == PCI_VENDOR_ID_VIA && pdev->device == 0x3483) {
 		xhci->quirks |= XHCI_LPM_SUPPORT;
+		xhci->quirks |= XHCI_EP_CTX_BROKEN_DCS;
+	}
 
 	if (pdev->vendor == PCI_VENDOR_ID_ASMEDIA &&
 		pdev->device == PCI_DEVICE_ID_ASMEDIA_1042_XHCI)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -562,7 +562,10 @@ void xhci_find_new_dequeue_state(struct
 	struct xhci_virt_ep *ep = &dev->eps[ep_index];
 	struct xhci_ring *ep_ring;
 	struct xhci_segment *new_seg;
+	struct xhci_segment *halted_seg = NULL;
 	union xhci_trb *new_deq;
+	union xhci_trb *halted_trb;
+	int index = 0;
 	dma_addr_t addr;
 	u64 hw_dequeue;
 	bool cycle_found = false;
@@ -600,7 +603,28 @@ void xhci_find_new_dequeue_state(struct
 	hw_dequeue = xhci_get_hw_deq(xhci, dev, ep_index, stream_id);
 	new_seg = ep_ring->deq_seg;
 	new_deq = ep_ring->dequeue;
-	state->new_cycle_state = hw_dequeue & 0x1;
+
+	/*
+	 * Quirk: xHC write-back of the DCS field in the hardware dequeue
+	 * pointer is wrong - use the cycle state of the TRB pointed to by
+	 * the dequeue pointer.
+	 */
+	if (xhci->quirks & XHCI_EP_CTX_BROKEN_DCS &&
+	    !(ep->ep_state & EP_HAS_STREAMS))
+		halted_seg = trb_in_td(xhci, cur_td->start_seg,
+				       cur_td->first_trb, cur_td->last_trb,
+				       hw_dequeue & ~0xf, false);
+	if (halted_seg) {
+		index = ((dma_addr_t)(hw_dequeue & ~0xf) - halted_seg->dma) /
+			 sizeof(*halted_trb);
+		halted_trb = &halted_seg->trbs[index];
+		state->new_cycle_state = halted_trb->generic.field[3] & 0x1;
+		xhci_dbg(xhci, "Endpoint DCS = %d TRB index = %d cycle = %d\n",
+			 (u8)(hw_dequeue & 0x1), index,
+			 state->new_cycle_state);
+	} else {
+		state->new_cycle_state = hw_dequeue & 0x1;
+	}
 	state->stream_id = stream_id;
 
 	/*
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1884,6 +1884,7 @@ struct xhci_hcd {
 #define XHCI_DISABLE_SPARSE	BIT_ULL(38)
 #define XHCI_SG_TRB_CACHE_SIZE_QUIRK	BIT_ULL(39)
 #define XHCI_NO_SOFT_RETRY	BIT_ULL(40)
+#define XHCI_EP_CTX_BROKEN_DCS	BIT_ULL(42)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;