[PATCH v2 39/49] usb: dwc2: Change TxFIFO and RxFIFO flushing flow

[Grigor Tovmasyan]

From: Minas Harutyunyan <hmi...@synopsys.com>

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

Signed-off-by: Minas Harutyunyan <hmi...@synopsys.com>
Signed-off-by: Grigor Tovmasyan <tovma...@synopsys.com>
---
 drivers/usb/dwc2/core.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index 2e02556013af..916c4bfdb2f9 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -870,10 +870,26 @@ 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 */
+       while (1) {
+               greset = dwc2_readl(hsotg->regs + GRSTCTL);
+               if (greset & GRSTCTL_AHBIDLE)
+                       break;
+
+               if (++count > 10000) {
+                       dev_warn(hsotg->dev,
+                                "%s() HANG! AHB Idle GRSTCTL=%0x\n",
+                               __func__, greset);
+                       return;
+               }
+               udelay(1);
+       }
+
        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) {
@@ -902,9 +918,23 @@ void dwc2_flush_rx_fifo(struct dwc2_hsotg *hsotg)
 
        dev_vdbg(hsotg->dev, "%s()\n", __func__);
 
-       greset = GRSTCTL_RXFFLSH;
-       dwc2_writel(greset, hsotg->regs + GRSTCTL);
+       /* Wait for AHB master IDLE state */
+       while (1) {
+               greset = dwc2_readl(hsotg->regs + GRSTCTL);
+               if (greset & GRSTCTL_AHBIDLE)
+                       break;
 
+               if (++count > 10000) {
+                       dev_warn(hsotg->dev,
+                                "%s() HANG! AHB Idle GRSTCTL=%0x\n",
+                               __func__, greset);
+                       return;
+               }
+               udelay(1);
+       }
+
+       /* Wait for RxFIFO flush done */
+       count = 0;
        do {
                greset = dwc2_readl(hsotg->regs + GRSTCTL);
                if (++count > 10000) {
-- 
2.11.0

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