From 91b0b7c961b5f50fd10bf949b4ed8b87280042a3 Mon Sep 17 00:00:00 2001
From: Alexander Reinert <alex@areinert.de>
Date: Fri, 15 Dec 2017 10:43:49 +0100
Subject: [PATCH] Adde kernel patch for Rockchip mainline inspired by
 https://github.com/TinkerBoard/debian_kernel/commit/cfe2329be3af16b324a2e338ad29484f36e753ab#diff-3a905b19fc3744269a82aeec54a7e405
 to avoid 100% cpu usage when using two usb uart devices like the FT232

---
 .../1008-dwc2-avoid_nak_for_csplit.patch      | 83 +++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 patch/kernel/rockchip-next/1008-dwc2-avoid_nak_for_csplit.patch

diff --git a/patch/kernel/rockchip-next/1008-dwc2-avoid_nak_for_csplit.patch b/patch/kernel/rockchip-next/1008-dwc2-avoid_nak_for_csplit.patch
new file mode 100644
index 0000000000..571f734366
--- /dev/null
+++ b/patch/kernel/rockchip-next/1008-dwc2-avoid_nak_for_csplit.patch
@@ -0,0 +1,83 @@
+diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
+index 7b6eb0ad513b..96b6935dc0d7 100644
+--- a/drivers/usb/dwc2/hcd.c
++++ b/drivers/usb/dwc2/hcd.c
+@@ -2748,6 +2748,8 @@ static int dwc2_assign_and_init_hc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
+ 	chan->xfer_len = urb->length - urb->actual_length;
+ 	chan->xfer_count = 0;
+ 
++	chan->csplit_nak = 0;
++
+ 	/* Set the split attributes if required */
+ 	if (qh->do_split)
+ 		dwc2_hc_init_split(hsotg, chan, qtd, urb);
+diff --git a/drivers/usb/dwc2/hcd.h b/drivers/usb/dwc2/hcd.h
+index 78e9e01051b5..e54f1351225b 100644
+--- a/drivers/usb/dwc2/hcd.h
++++ b/drivers/usb/dwc2/hcd.h
+@@ -143,6 +143,7 @@ struct dwc2_host_chan {
+ 	u8 halt_pending;
+ 	u8 do_split;
+ 	u8 complete_split;
++	u8 csplit_nak;
+ 	u8 hub_addr;
+ 	u8 hub_port;
+ 	u8 xact_pos;
+diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c
+index 916d991b96b8..551cfacd2252 100644
+--- a/drivers/usb/dwc2/hcd_intr.c
++++ b/drivers/usb/dwc2/hcd_intr.c
+@@ -691,6 +691,7 @@ static void dwc2_release_channel(struct dwc2_hsotg *hsotg,
+ 	enum dwc2_transaction_type tr_type;
+ 	u32 haintmsk;
+ 	int free_qtd = 0;
++	int continue_trans = 1;
+ 
+ 	if (dbg_hc(chan))
+ 		dev_vdbg(hsotg->dev, "  %s: channel %d, halt_status %d\n",
+@@ -719,6 +720,7 @@ static void dwc2_release_channel(struct dwc2_hsotg *hsotg,
+ 		 * deactivated. Don't want to do anything except release the
+ 		 * host channel and try to queue more transfers.
+ 		 */
++		continue_trans = 0;
+ 		goto cleanup;
+ 	case DWC2_HC_XFER_PERIODIC_INCOMPLETE:
+ 		dev_vdbg(hsotg->dev, "  Complete URB with I/O error\n");
+@@ -730,6 +732,11 @@ static void dwc2_release_channel(struct dwc2_hsotg *hsotg,
+ 		break;
+ 	}
+ 
++	if (chan->csplit_nak) {
++		continue_trans = 0;
++		chan->csplit_nak = 0;
++	}
++
+ 	dwc2_deactivate_qh(hsotg, chan->qh, free_qtd);
+ 
+ cleanup:
+@@ -767,9 +774,11 @@ static void dwc2_release_channel(struct dwc2_hsotg *hsotg,
+ 	dwc2_writel(haintmsk, hsotg->regs + HAINTMSK);
+ 
+ 	/* Try to queue more transfers now that there's a free channel */
+-	tr_type = dwc2_hcd_select_transactions(hsotg);
+-	if (tr_type != DWC2_TRANSACTION_NONE)
+-		dwc2_hcd_queue_transactions(hsotg, tr_type);
++	if (continue_trans) {
++		tr_type = dwc2_hcd_select_transactions(hsotg);
++		if (tr_type != DWC2_TRANSACTION_NONE)
++			dwc2_hcd_queue_transactions(hsotg, tr_type);
++	}
+ }
+ 
+ /*
+@@ -1205,6 +1214,7 @@ static void dwc2_hc_nak_intr(struct dwc2_hsotg *hsotg,
+ 	if (chan->do_split) {
+ 		if (chan->complete_split)
+ 			qtd->error_count = 0;
++		chan->csplit_nak = 1;
+ 		qtd->complete_split = 0;
+ 		dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NAK);
+ 		goto handle_nak_done;
+-- 
+2.11.0
+