From: Jagan Teki jagan@amarulasolutions.com
By default when core sees any transaction error (CRC or overflow) it replies with terminating retry ACK (Retry=1 and Nump == 0).
Enabling this Auto Retry feature in controller will make the core send a non-terminanting ACK upon such transaction errors. That is, ACK TP with Retry=1 and Nump != 0.
Doing so will give controller a chance to recover from transient error conditions.
Reference from below Linux commit,
commit <b138e23d3dff> ("usb: dwc3: core: Enable AutoRetry feature in the controller")
Cc: Marek Vasut marex@denx.de Signed-off-by: Jagan Teki jagan@amarulasolutions.com Reviewed-by: Kever Yang kever.yang@rock-chips.com --- drivers/usb/dwc3/core.c | 9 +++++++++ drivers/usb/dwc3/core.h | 3 +++ 2 files changed, 12 insertions(+)
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index dc92f471c1..aab6c34c2d 100644 --- a/drivers/usb/dwc3/core.c +++ b/drivers/usb/dwc3/core.c @@ -995,6 +995,15 @@ int dwc3_init(struct dwc3 *dwc) dwc3_writel(dwc->regs, DWC3_GUCTL1, reg); }
+ if (dwc->dr_mode == USB_DR_MODE_HOST || + dwc->dr_mode == USB_DR_MODE_OTG) { + reg = dwc3_readl(dwc->regs, DWC3_GUCTL); + + reg |= DWC3_GUCTL_HSTINAUTORETRY; + + dwc3_writel(dwc->regs, DWC3_GUCTL, reg); + } + ret = dwc3_core_init_mode(dwc); if (ret) goto mode_fail; diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h index b510d8a983..2adcaf0029 100644 --- a/drivers/usb/dwc3/core.h +++ b/drivers/usb/dwc3/core.h @@ -160,6 +160,9 @@ #define DWC3_GCTL_GBLHIBERNATIONEN (1 << 1) #define DWC3_GCTL_DSBLCLKGTNG (1 << 0)
+/* Global User Control Register */ +#define DWC3_GUCTL_HSTINAUTORETRY BIT(14) + /* Global User Control 1 Register */ #define DWC3_GUCTL1_TX_IPGAP_LINECHECK_DIS BIT(28) #define DWC3_GUCTL1_DEV_L1_EXIT_BY_HW BIT(24)