usb: dwc3: core: configure TX/RX threshold for DWC3_IP

In Synopsys's dwc3 data book:
To avoid underrun and overrun during the burst, in a high-latency bus
system (like USB), threshold and burst size control is provided through
GTXTHRCFG and GRXTHRCFG registers.

In Realtek DHC SoC, DWC3 USB 3.0 uses AHB system bus. When dwc3 is
connected with USB 2.5G Ethernet, there will be overrun problem.
Therefore, setting TX/RX thresholds can avoid this issue.
Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20230912041904.30721-1-stanley_chang@realtek.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/core.c

@@ -1057,6 +1057,111 @@ static void dwc3_set_power_down_clk_scale(struct dwc3 *dwc)
 	}
 }
 
+static void dwc3_config_threshold(struct dwc3 *dwc)
+{
+	u32 reg;
+	u8 rx_thr_num;
+	u8 rx_maxburst;
+	u8 tx_thr_num;
+	u8 tx_maxburst;
+
+	/*
+	 * Must config both number of packets and max burst settings to enable
+	 * RX and/or TX threshold.
+	 */
+	if (!DWC3_IP_IS(DWC3) && dwc->dr_mode == USB_DR_MODE_HOST) {
+		rx_thr_num = dwc->rx_thr_num_pkt_prd;
+		rx_maxburst = dwc->rx_max_burst_prd;
+		tx_thr_num = dwc->tx_thr_num_pkt_prd;
+		tx_maxburst = dwc->tx_max_burst_prd;
+
+		if (rx_thr_num && rx_maxburst) {
+			reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
+			reg |= DWC31_RXTHRNUMPKTSEL_PRD;
+
+			reg &= ~DWC31_RXTHRNUMPKT_PRD(~0);
+			reg |= DWC31_RXTHRNUMPKT_PRD(rx_thr_num);
+
+			reg &= ~DWC31_MAXRXBURSTSIZE_PRD(~0);
+			reg |= DWC31_MAXRXBURSTSIZE_PRD(rx_maxburst);
+
+			dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
+		}
+
+		if (tx_thr_num && tx_maxburst) {
+			reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
+			reg |= DWC31_TXTHRNUMPKTSEL_PRD;
+
+			reg &= ~DWC31_TXTHRNUMPKT_PRD(~0);
+			reg |= DWC31_TXTHRNUMPKT_PRD(tx_thr_num);
+
+			reg &= ~DWC31_MAXTXBURSTSIZE_PRD(~0);
+			reg |= DWC31_MAXTXBURSTSIZE_PRD(tx_maxburst);
+
+			dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
+		}
+	}
+
+	rx_thr_num = dwc->rx_thr_num_pkt;
+	rx_maxburst = dwc->rx_max_burst;
+	tx_thr_num = dwc->tx_thr_num_pkt;
+	tx_maxburst = dwc->tx_max_burst;
+
+	if (DWC3_IP_IS(DWC3)) {
+		if (rx_thr_num && rx_maxburst) {
+			reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
+			reg |= DWC3_GRXTHRCFG_PKTCNTSEL;
+
+			reg &= ~DWC3_GRXTHRCFG_RXPKTCNT(~0);
+			reg |= DWC3_GRXTHRCFG_RXPKTCNT(rx_thr_num);
+
+			reg &= ~DWC3_GRXTHRCFG_MAXRXBURSTSIZE(~0);
+			reg |= DWC3_GRXTHRCFG_MAXRXBURSTSIZE(rx_maxburst);
+
+			dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
+		}
+
+		if (tx_thr_num && tx_maxburst) {
+			reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
+			reg |= DWC3_GTXTHRCFG_PKTCNTSEL;
+
+			reg &= ~DWC3_GTXTHRCFG_TXPKTCNT(~0);
+			reg |= DWC3_GTXTHRCFG_TXPKTCNT(tx_thr_num);
+
+			reg &= ~DWC3_GTXTHRCFG_MAXTXBURSTSIZE(~0);
+			reg |= DWC3_GTXTHRCFG_MAXTXBURSTSIZE(tx_maxburst);
+
+			dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
+		}
+	} else {
+		if (rx_thr_num && rx_maxburst) {
+			reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
+			reg |= DWC31_GRXTHRCFG_PKTCNTSEL;
+
+			reg &= ~DWC31_GRXTHRCFG_RXPKTCNT(~0);
+			reg |= DWC31_GRXTHRCFG_RXPKTCNT(rx_thr_num);
+
+			reg &= ~DWC31_GRXTHRCFG_MAXRXBURSTSIZE(~0);
+			reg |= DWC31_GRXTHRCFG_MAXRXBURSTSIZE(rx_maxburst);
+
+			dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
+		}
+
+		if (tx_thr_num && tx_maxburst) {
+			reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
+			reg |= DWC31_GTXTHRCFG_PKTCNTSEL;
+
+			reg &= ~DWC31_GTXTHRCFG_TXPKTCNT(~0);
+			reg |= DWC31_GTXTHRCFG_TXPKTCNT(tx_thr_num);
+
+			reg &= ~DWC31_GTXTHRCFG_MAXTXBURSTSIZE(~0);
+			reg |= DWC31_GTXTHRCFG_MAXTXBURSTSIZE(tx_maxburst);
+
+			dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
+		}
+	}
+}
+
 /**
  * dwc3_core_init - Low-level initialization of DWC3 Core
  * @dwc: Pointer to our controller context structure
@@ -1209,42 +1314,7 @@ static int dwc3_core_init(struct dwc3 *dwc)
 		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
 	}
 
-	/*
-	 * Must config both number of packets and max burst settings to enable
-	 * RX and/or TX threshold.
-	 */
-	if (!DWC3_IP_IS(DWC3) && dwc->dr_mode == USB_DR_MODE_HOST) {
-		u8 rx_thr_num = dwc->rx_thr_num_pkt_prd;
-		u8 rx_maxburst = dwc->rx_max_burst_prd;
-		u8 tx_thr_num = dwc->tx_thr_num_pkt_prd;
-		u8 tx_maxburst = dwc->tx_max_burst_prd;
-
-		if (rx_thr_num && rx_maxburst) {
-			reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
-			reg |= DWC31_RXTHRNUMPKTSEL_PRD;
-
-			reg &= ~DWC31_RXTHRNUMPKT_PRD(~0);
-			reg |= DWC31_RXTHRNUMPKT_PRD(rx_thr_num);
-
-			reg &= ~DWC31_MAXRXBURSTSIZE_PRD(~0);
-			reg |= DWC31_MAXRXBURSTSIZE_PRD(rx_maxburst);
-
-			dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
-		}
-
-		if (tx_thr_num && tx_maxburst) {
-			reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
-			reg |= DWC31_TXTHRNUMPKTSEL_PRD;
-
-			reg &= ~DWC31_TXTHRNUMPKT_PRD(~0);
-			reg |= DWC31_TXTHRNUMPKT_PRD(tx_thr_num);
-
-			reg &= ~DWC31_MAXTXBURSTSIZE_PRD(~0);
-			reg |= DWC31_MAXTXBURSTSIZE_PRD(tx_maxburst);
-
-			dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
-		}
-	}
+	dwc3_config_threshold(dwc);
 
 	return 0;
 
@@ -1380,6 +1450,10 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 	u8			lpm_nyet_threshold;
 	u8			tx_de_emphasis;
 	u8			hird_threshold;
+	u8			rx_thr_num_pkt = 0;
+	u8			rx_max_burst = 0;
+	u8			tx_thr_num_pkt = 0;
+	u8			tx_max_burst = 0;
 	u8			rx_thr_num_pkt_prd = 0;
 	u8			rx_max_burst_prd = 0;
 	u8			tx_thr_num_pkt_prd = 0;
@@ -1442,6 +1516,14 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				"snps,usb2-lpm-disable");
 	dwc->usb2_gadget_lpm_disable = device_property_read_bool(dev,
 				"snps,usb2-gadget-lpm-disable");
+	device_property_read_u8(dev, "snps,rx-thr-num-pkt",
+				&rx_thr_num_pkt);
+	device_property_read_u8(dev, "snps,rx-max-burst",
+				&rx_max_burst);
+	device_property_read_u8(dev, "snps,tx-thr-num-pkt",
+				&tx_thr_num_pkt);
+	device_property_read_u8(dev, "snps,tx-max-burst",
+				&tx_max_burst);
 	device_property_read_u8(dev, "snps,rx-thr-num-pkt-prd",
 				&rx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,rx-max-burst-prd",
@@ -1523,6 +1605,12 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 
 	dwc->hird_threshold = hird_threshold;
 
+	dwc->rx_thr_num_pkt = rx_thr_num_pkt;
+	dwc->rx_max_burst = rx_max_burst;
+
+	dwc->tx_thr_num_pkt = tx_thr_num_pkt;
+	dwc->tx_max_burst = tx_max_burst;
+
 	dwc->rx_thr_num_pkt_prd = rx_thr_num_pkt_prd;
 	dwc->rx_max_burst_prd = rx_max_burst_prd;
 

drivers/usb/dwc3/core.h

@@ -211,6 +211,11 @@
 #define DWC3_GRXTHRCFG_RXPKTCNT(n) (((n) & 0xf) << 24)
 #define DWC3_GRXTHRCFG_PKTCNTSEL BIT(29)
 
+/* Global TX Threshold Configuration Register */
+#define DWC3_GTXTHRCFG_MAXTXBURSTSIZE(n) (((n) & 0xff) << 16)
+#define DWC3_GTXTHRCFG_TXPKTCNT(n) (((n) & 0xf) << 24)
+#define DWC3_GTXTHRCFG_PKTCNTSEL BIT(29)
+
 /* Global RX Threshold Configuration Register for DWC_usb31 only */
 #define DWC31_GRXTHRCFG_MAXRXBURSTSIZE(n)	(((n) & 0x1f) << 16)
 #define DWC31_GRXTHRCFG_RXPKTCNT(n)		(((n) & 0x1f) << 21)
@@ -1045,6 +1050,10 @@ struct dwc3_scratchpad_array {
  * @test_mode_nr: test feature selector
  * @lpm_nyet_threshold: LPM NYET response threshold
  * @hird_threshold: HIRD threshold
+ * @rx_thr_num_pkt: USB receive packet count
+ * @rx_max_burst: max USB receive burst size
+ * @tx_thr_num_pkt: USB transmit packet count
+ * @tx_max_burst: max USB transmit burst size
  * @rx_thr_num_pkt_prd: periodic ESS receive packet count
  * @rx_max_burst_prd: max periodic ESS receive burst size
  * @tx_thr_num_pkt_prd: periodic ESS transmit packet count
@@ -1273,6 +1282,10 @@ struct dwc3 {
 	u8			test_mode_nr;
 	u8			lpm_nyet_threshold;
 	u8			hird_threshold;
+	u8			rx_thr_num_pkt;
+	u8			rx_max_burst;
+	u8			tx_thr_num_pkt;
+	u8			tx_max_burst;
 	u8			rx_thr_num_pkt_prd;
 	u8			rx_max_burst_prd;
 	u8			tx_thr_num_pkt_prd;