STAR 9001346572 addresses a USB 2.0 endpoint blocking issue in host mode
for controller versions DWC_usb31 1.70a and 1.80a. This issue affects
devices on both high-speed and full-speed bus instances. When all
endpoint caches are filled and a single active endpoint receives
continuous NAK responses, data transfers to other endpoints may get
blocked.
To resolve this, for controller versions DWC_usb31 1.70a and 1.80a, the
GUCTL3 bit[16] (USB2.0 Internal Retry Disable) is set to 1. This bit
disables the USB2.0 internal retry feature and ensures proper eviction
handling in the host controller endpoind cache. The GUCTL3[16] register
function is available only from DWC_usb31 version 1.70a.
Signed-off-by: Faisal Hassan <quic_faisalh@xxxxxxxxxxx>
---
drivers/usb/dwc3/core.c | 20 ++++++++++++++++++++
drivers/usb/dwc3/core.h | 1 +
2 files changed, 21 insertions(+)
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 98114c2827c0..c5c36134ddd9 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1475,6 +1475,26 @@ static int dwc3_core_init(struct dwc3 *dwc)
dwc3_writel(dwc->regs, DWC3_LLUCTL, reg);
}
+ /*
+ * STAR 9001346572: This issue affects DWC_usb31 versions 1.80a and
+ * prior. When an active endpoint not currently cached in the host
+ * controller is chosen to be cached to the same index as an endpoint
+ * receiving NAKs, the endpoint receiving NAKs enters continuous
+ * retry mode. This prevents it from being evicted from the host
+ * controller cache, blocking the new endpoint from being cached and
+ * serviced.
+ *
+ * To resolve this, for controller versions 1.70a and 1.80a, set the
+ * GUCTL3 bit[16] (USB2.0 Internal Retry Disable) to 1. This bit
+ * disables the USB2.0 internal retry feature. The GUCTL3[16] register
+ * function is available only from version 1.70a.
+ */
+ if (DWC3_VER_IS_WITHIN(DWC31, 170A, 180A)) {
+ reg = dwc3_readl(dwc->regs, DWC3_GUCTL3);
+ reg |= DWC3_GUCTL3_USB20_RETRY_DISABLE;
+ dwc3_writel(dwc->regs, DWC3_GUCTL3, reg);
+ }
+
return 0;
err_power_off_phy:
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index eab81dfdcc35..5417058c5943 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -425,6 +425,7 @@
/* Global User Control Register 3 */
#define DWC3_GUCTL3_SPLITDISABLE BIT(14)
+#define DWC3_GUCTL3_USB20_RETRY_DISABLE BIT(16)
/* Device Configuration Register */
#define DWC3_DCFG_NUMLANES(n) (((n) & 0x3) << 30) /* DWC_usb32 only */
--
2.17.1
