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Commit 07e7f47b authored by Felipe Balbi's avatar Felipe Balbi
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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: default avatarFelipe Balbi <balbi@ti.com>
parent 1522d703

drivers/usb/dwc3/gadget.c

+18 −1
Original line number Original line 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_readl(dwc->regs, DWC3_DCFG);

	reg &= ~(DWC3_DCFG_SPEED_MASK);

	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;

		reg |= dwc->maximum_speed;

	dwc3_writel(dwc->regs, DWC3_DCFG, reg);

	dwc3_writel(dwc->regs, DWC3_DCFG, reg);