usb: xhci: fix loss of data on Cadence xHC

Streams should flush their TRB cache, re-read TRBs, and start executing
TRBs from the beginning of the new dequeue pointer after a 'Set TR Dequeue
Pointer' command.

Cadence controllers may fail to start from the beginning of the dequeue
TRB as it doesn't clear the Opaque 'RsvdO' field of the stream context
during 'Set TR Dequeue' command. This stream context area is where xHC
stores information about the last partially executed TD when a stream
is stopped. xHC uses this information to resume the transfer where it left
mid TD, when the stream is restarted.

Patch fixes this by clearing out all RsvdO fields before initializing new
Stream transfer using a 'Set TR Dequeue Pointer' command.

Fixes: 3d82904 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
cc: [email protected]
Signed-off-by: Pawel Laszczak <[email protected]>
Reviewed-by: Peter Chen <[email protected]>
Link: https://lore.kernel.org/r/PH7PR07MB95386A40146E3EC64086F409DD9D2@PH7PR07MB9538.namprd07.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: pawellcdns

drivers/usb/cdns3/host.c

@@ -62,7 +62,9 @@ static const struct xhci_plat_priv xhci_plat_cdns3_xhci = {
 	.resume_quirk = xhci_cdns3_resume_quirk,
 };
 
-static const struct xhci_plat_priv xhci_plat_cdnsp_xhci;
+static const struct xhci_plat_priv xhci_plat_cdnsp_xhci = {
+	.quirks = XHCI_CDNS_SCTX_QUIRK,
+};
 
 static int __cdns_host_init(struct cdns *cdns)
 {

drivers/usb/host/xhci-pci.c

@@ -81,6 +81,9 @@
 #define PCI_DEVICE_ID_ASMEDIA_2142_XHCI			0x2142
 #define PCI_DEVICE_ID_ASMEDIA_3242_XHCI			0x3242
 
+#define PCI_DEVICE_ID_CADENCE				0x17CD
+#define PCI_DEVICE_ID_CADENCE_SSP			0x0200
+
 static const char hcd_name[] = "xhci_hcd";
 
 static struct hc_driver __read_mostly xhci_pci_hc_driver;
@@ -474,6 +477,10 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 			xhci->quirks |= XHCI_ZHAOXIN_TRB_FETCH;
 	}
 
+	if (pdev->vendor == PCI_DEVICE_ID_CADENCE &&
+	    pdev->device == PCI_DEVICE_ID_CADENCE_SSP)
+		xhci->quirks |= XHCI_CDNS_SCTX_QUIRK;
+
 	/* xHC spec requires PCI devices to support D3hot and D3cold */
 	if (xhci->hci_version >= 0x120)
 		xhci->quirks |= XHCI_DEFAULT_PM_RUNTIME_ALLOW;

drivers/usb/host/xhci-ring.c

@@ -1399,6 +1399,20 @@ static void xhci_handle_cmd_set_deq(struct xhci_hcd *xhci, int slot_id,
 			struct xhci_stream_ctx *ctx =
 				&ep->stream_info->stream_ctx_array[stream_id];
 			deq = le64_to_cpu(ctx->stream_ring) & SCTX_DEQ_MASK;
+
+			/*
+			 * Cadence xHCI controllers store some endpoint state
+			 * information within Rsvd0 fields of Stream Endpoint
+			 * context. This field is not cleared during Set TR
+			 * Dequeue Pointer command which causes XDMA to skip
+			 * over transfer ring and leads to data loss on stream
+			 * pipe.
+			 * To fix this issue driver must clear Rsvd0 field.
+			 */
+			if (xhci->quirks & XHCI_CDNS_SCTX_QUIRK) {
+				ctx->reserved[0] = 0;
+				ctx->reserved[1] = 0;
+			}
 		} else {
 			deq = le64_to_cpu(ep_ctx->deq) & ~EP_CTX_CYCLE_MASK;
 		}

drivers/usb/host/xhci.h

@@ -1623,6 +1623,7 @@ struct xhci_hcd {
 #define XHCI_ZHAOXIN_TRB_FETCH	BIT_ULL(45)
 #define XHCI_ZHAOXIN_HOST	BIT_ULL(46)
 #define XHCI_WRITE_64_HI_LO	BIT_ULL(47)
+#define XHCI_CDNS_SCTX_QUIRK	BIT_ULL(48)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;