usb: dwc3: workaround: metastability state on Run/Stop bit (07e7f47b) · Commits · 戴 / test

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>

drivers/usb/dwc3/gadget.c

+18 −1

Original line number	Diff line number	Diff line
		@@ -1356,6 +1356,23 @@ static int dwc3_gadget_start(struct usb_gadget *g,

		reg = dwc3_readl(dwc->regs, DWC3_DCFG);
		reg &= ~(DWC3_DCFG_SPEED_MASK);

		/**
		* 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);

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