xhci: add quirk for host controllers that don't update endpoint DCS

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.

See: https://github.com/raspberrypi/linux/issues/3060

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.org>

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 84da840..551ef64 100644 (file)
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -269,8 +269,10 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
                        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)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index db8612e..6cf0b04 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -533,7 +533,10 @@ void xhci_find_new_dequeue_state(struct xhci_hcd *xhci,
        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;
@@ -571,7 +574,28 @@ void xhci_find_new_dequeue_state(struct xhci_hcd *xhci,
        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;
 
        /*

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index d90c0d5..0aa1cce 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1879,6 +1879,7 @@ struct xhci_hcd {
 #define XHCI_SKIP_PHY_INIT     BIT_ULL(37)
 #define XHCI_DISABLE_SPARSE    BIT_ULL(38)
 #define XHCI_SG_TRB_CACHE_SIZE_QUIRK   BIT_ULL(39)
+#define XHCI_EP_CTX_BROKEN_DCS BIT_ULL(40)
 
        unsigned int            num_active_eps;
        unsigned int            limit_active_eps;