usb: dwc3: workaround: metastability state on Run/Stop bit
All revisions prior to 2.20a have a known issue which
causes metastability state on Run/Stop bit if we
configure the core to work on any of the USB2-only
speeds.
The suggested workaround is just to never configure the
core to anything other than SuperSpeed.
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 5255fe97..dda56b8 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1356,7 +1356,24 @@
reg = dwc3_readl(dwc->regs, DWC3_DCFG);
reg &= ~(DWC3_DCFG_SPEED_MASK);
- reg |= dwc->maximum_speed;
+
+ /**
+ * WORKAROUND: DWC3 revision < 2.20a have an issue
+ * which would cause metastability state on Run/Stop
+ * bit if we try to force the IP to USB2-only mode.
+ *
+ * Because of that, we cannot configure the IP to any
+ * speed other than the SuperSpeed
+ *
+ * Refers to:
+ *
+ * STAR#9000525659: Clock Domain Crossing on DCTL in
+ * USB 2.0 Mode
+ */
+ if (dwc->revision < DWC3_REVISION_220A)
+ reg |= DWC3_DCFG_SUPERSPEED;
+ else
+ reg |= dwc->maximum_speed;
dwc3_writel(dwc->regs, DWC3_DCFG, reg);
dwc->start_config_issued = false;