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@xxxxxx> --- drivers/usb/dwc3/gadget.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 5255fe9..dda56b8 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1356,7 +1356,24 @@ static int dwc3_gadget_start(struct usb_gadget *g, 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; -- 1.7.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
