[01/15] usb: dwc3: Device SoftReset PHY synchonization delay

[Felipe Balbi <balbi@kernel.org>]

Hi,

Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
> From DWC_usb31 databook section 1.3.2, once DWC3_DCTL_CSFTRST bit is
> cleared, we must wait at least 50ms before accessing the PHY domain
> (synchronization delay).
>
> Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
> ---
>  drivers/usb/dwc3/core.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 07832509584f..7d21f21707f5 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -228,12 +228,23 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
>  	do {
>  		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
>  		if (!(reg & DWC3_DCTL_CSFTRST))
> -			return 0;
> +			goto done;
>  
>  		udelay(1);
>  	} while (--retries);
>  
>  	return -ETIMEDOUT;
> +
> +done:
> +	/*
> +	 * For DWC_usb31 controller, once DWC3_DCTL_CSFTRST bit is cleared,
> +	 * we must wait at least 50ms before accessing the PHY domain
> +	 * (synchronization delay). DWC_usb31 Databook section 1.3.2.
> +	 */
> +	if (dwc3_is_usb31(dwc))
> +		mdelay(50);

we don't have any locks held. Why are you busy looping for an entire
50ms? Why don't you msleep() here?