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usb: dwc3: workaround: metastability state on Run/Stop bit

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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>
This commit is contained in:
Felipe Balbi 2012-03-23 12:20:31 +02:00
parent 1522d7034d
commit 07e7f47b6d
1 changed files with 18 additions and 1 deletions
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19
drivers/usb/dwc3/gadget.c
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@ -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;