From: Dom Cobley <popcornmix@gmail.com>
Date: Mon, 31 Jul 2023 12:47:10 +0000 (+0100)
Subject: Revert "Revert "xhci: add quirk for host controllers that don't update endpoint DCS""
X-Git-Tag: accepted/tizen/unified/20240422.153132~919
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=901ac8af571f3ebbdfbec531591885e3dc9aa233;p=platform%2Fkernel%2Flinux-rpi.git

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

This reverts commit 5bef4b3cb95a5b883dfec8b3ffc0d671323d55bb.

We don't agree with upstream revert so undo it.
---

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index d6fc08e..b61e6d7 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -479,8 +479,10 @@ 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 c410a98..571f24d 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -626,8 +626,11 @@ static int xhci_move_dequeue_past_td(struct xhci_hcd *xhci,
 	struct xhci_ring *ep_ring;
 	struct xhci_command *cmd;
 	struct xhci_segment *new_seg;
+	struct xhci_segment *halted_seg = NULL;
 	union xhci_trb *new_deq;
 	int new_cycle;
+	union xhci_trb *halted_trb;
+	int index = 0;
 	dma_addr_t addr;
 	u64 hw_dequeue;
 	bool cycle_found = false;
@@ -665,7 +668,27 @@ static int xhci_move_dequeue_past_td(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;
-	new_cycle = 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, td->start_seg,
+				       td->first_trb, 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];
+		new_cycle = halted_trb->generic.field[3] & 0x1;
+		xhci_dbg(xhci, "Endpoint DCS = %d TRB index = %d cycle = %d\n",
+			 (u8)(hw_dequeue & 0x1), index, new_cycle);
+	} else {
+		new_cycle = hw_dequeue & 0x1;
+	}
 
 	/*
 	 * We want to find the pointer, segment and cycle state of the new trb