linux-kernel - [PATCH v2] usb: dwc2: Change TxFIFO and RxFIFO flushing flow

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Date:   Fri, 8 Dec 2017 12:30:19 +0400
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     John Youn <John.Youn@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
Subject: [PATCH v2] usb: dwc2: Change TxFIFO and RxFIFO flushing flow

Before flushing fifos required to check AHB master state and
flush when AHB master is in IDLE state.

Signed-off-by: Minas Harutyunyan <hminas@...opsys.com>
---
 drivers/usb/dwc2/core.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index dbca3b8890da..4d2a8c452e6b 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -670,10 +670,23 @@ void dwc2_flush_tx_fifo(struct dwc2_hsotg *hsotg, const int num)
 
 	dev_vdbg(hsotg->dev, "Flush Tx FIFO %d\n", num);
 
+	/* Wait for AHB master IDLE state */
+	do {
+		greset = dwc2_readl(hsotg->regs + GRSTCTL);
+		if (++count > 10000) {
+			dev_warn(hsotg->dev,
+				 "%s() HANG! AHB Idle GRSTCTL=%0x\n",
+				 __func__, greset);
+			return;
+		}
+		udelay(1);
+	} while (!(greset & GRSTCTL_AHBIDLE));
+
 	greset = GRSTCTL_TXFFLSH;
 	greset |= num << GRSTCTL_TXFNUM_SHIFT & GRSTCTL_TXFNUM_MASK;
 	dwc2_writel(greset, hsotg->regs + GRSTCTL);
 
+	count = 0;
 	do {
 		greset = dwc2_readl(hsotg->regs + GRSTCTL);
 		if (++count > 10000) {
@@ -702,9 +715,23 @@ void dwc2_flush_rx_fifo(struct dwc2_hsotg *hsotg)
 
 	dev_vdbg(hsotg->dev, "%s()\n", __func__);
 
+	/* Wait for AHB master IDLE state */
+	do {
+		greset = dwc2_readl(hsotg->regs + GRSTCTL);
+		if (++count > 10000) {
+			dev_warn(hsotg->dev,
+				 "%s() HANG! AHB Idle GRSTCTL=%0x\n",
+				 __func__, greset);
+			return;
+		}
+		udelay(1);
+	} while (!(greset & GRSTCTL_AHBIDLE));
+
 	greset = GRSTCTL_RXFFLSH;
 	dwc2_writel(greset, hsotg->regs + GRSTCTL);
 
+	/* Wait for RxFIFO flush done */
+	count = 0;
 	do {
 		greset = dwc2_readl(hsotg->regs + GRSTCTL);
 		if (++count > 10000) {
-- 
2.11.0