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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 124 insertions, 36 deletions

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9c6bf054f15d..44ee8526dc28 100644
--- a/drivers/usb/dwc3/core.c
+++ b/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;