linux-kernel - Re: [PATCH v2] usb: dwc3-am62: Fix up wake-up configuration and spurious wake up

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Message-ID: <20230324183601.pyt7od36chdv2wkb@synopsys.com>
Date:   Fri, 24 Mar 2023 18:36:04 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Roger Quadros <rogerq@...nel.org>
CC:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "stern@...land.harvard.edu" <stern@...land.harvard.edu>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "vigneshr@...com" <vigneshr@...com>, "srk@...com" <srk@...com>,
        "r-gunasekaran@...com" <r-gunasekaran@...com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] usb: dwc3-am62: Fix up wake-up configuration and
 spurious wake up

On Fri, Mar 24, 2023, Roger Quadros wrote:
> Explicitly set and clear wakeup config so we don't leave anything
> to chance.
> 
> Clear wakeup status on suspend so we know what caused wake up.
> 
> The LINESTATE wake up should not be enabled in device mode
> if we are not connected to a USB host and in USB suspend (U2/L3)
> else it will cause spurious wake up.
> 
> For now, don't enable LINESTATE. This means wake up from
> USB resume will not work but at least we won't have any spurious
> wake ups.
> 
> Signed-off-by: Roger Quadros <rogerq@...nel.org>
> ---
> Changelog:
> v2: don't enable LINESTATE wake-up at all in device mode.
> 
>  drivers/usb/dwc3/dwc3-am62.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
> index 859b48279658..b22fb78bc8e7 100644
> --- a/drivers/usb/dwc3/dwc3-am62.c
> +++ b/drivers/usb/dwc3/dwc3-am62.c
> @@ -60,6 +60,13 @@
>  #define USBSS_WAKEUP_CFG_SESSVALID_EN	BIT(1)
>  #define USBSS_WAKEUP_CFG_VBUSVALID_EN	BIT(0)
>  
> +#define USBSS_WAKEUP_CFG_ALL	(USBSS_WAKEUP_CFG_VBUSVALID_EN | \
> +				 USBSS_WAKEUP_CFG_SESSVALID_EN | \
> +				 USBSS_WAKEUP_CFG_LINESTATE_EN | \
> +				 USBSS_WAKEUP_CFG_OVERCURRENT_EN)
> +
> +#define USBSS_WAKEUP_CFG_NONE	0
> +
>  /* WAKEUP STAT register bits */
>  #define USBSS_WAKEUP_STAT_OVERCURRENT	BIT(4)
>  #define USBSS_WAKEUP_STAT_LINESTATE	BIT(3)
> @@ -103,6 +110,7 @@ struct dwc3_data {
>  	struct regmap *syscon;
>  	unsigned int offset;
>  	unsigned int vbus_divider;
> +	u32 wakeup_stat;
>  };
>  
>  static const int dwc3_ti_rate_table[] = {	/* in KHZ */
> @@ -302,12 +310,17 @@ static int dwc3_ti_suspend_common(struct device *dev)
>  		/* Set wakeup config enable bits */
>  		reg = dwc3_ti_readl(data, USBSS_WAKEUP_CONFIG);
>  		if (current_prtcap_dir == DWC3_GCTL_PRTCAP_HOST) {
> -			reg |= USBSS_WAKEUP_CFG_LINESTATE_EN | USBSS_WAKEUP_CFG_OVERCURRENT_EN;
> +			reg = USBSS_WAKEUP_CFG_LINESTATE_EN | USBSS_WAKEUP_CFG_OVERCURRENT_EN;
>  		} else {
> -			reg |= USBSS_WAKEUP_CFG_OVERCURRENT_EN | USBSS_WAKEUP_CFG_LINESTATE_EN |
> -			       USBSS_WAKEUP_CFG_VBUSVALID_EN;
> +			reg = USBSS_WAKEUP_CFG_VBUSVALID_EN | USBSS_WAKEUP_CFG_SESSVALID_EN;
> +			/*
> +			 * Enable LINESTATE wake up only if connected to bus
> +			 * and in U2/L3 state else it causes spurious wake-up.
> +			 */
>  		}
>  		dwc3_ti_writel(data, USBSS_WAKEUP_CONFIG, reg);
> +		/* clear wakeup status so we know what caused the wake up */
> +		dwc3_ti_writel(data, USBSS_WAKEUP_STAT, USBSS_WAKEUP_STAT_CLR);
>  	}
>  
>  	clk_disable_unprepare(data->usb2_refclk);
> @@ -324,16 +337,11 @@ static int dwc3_ti_resume_common(struct device *dev)
>  
>  	if (device_may_wakeup(dev)) {
>  		/* Clear wakeup config enable bits */
> -		reg = dwc3_ti_readl(data, USBSS_WAKEUP_CONFIG);
> -		reg &= ~(USBSS_WAKEUP_CFG_OVERCURRENT_EN | USBSS_WAKEUP_CFG_LINESTATE_EN |
> -			 USBSS_WAKEUP_CFG_VBUSVALID_EN);
> -		dwc3_ti_writel(data, USBSS_WAKEUP_CONFIG, reg);
> +		dwc3_ti_writel(data, USBSS_WAKEUP_CONFIG, USBSS_WAKEUP_CFG_NONE);
>  	}
>  
>  	reg = dwc3_ti_readl(data, USBSS_WAKEUP_STAT);
> -	/* Clear the wakeup status with wakeup clear bit */
> -	reg |= USBSS_WAKEUP_STAT_CLR;
> -	dwc3_ti_writel(data, USBSS_WAKEUP_STAT, reg);
> +	data->wakeup_stat = reg;
>  
>  	return 0;
>  }
> -- 
> 2.34.1
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>

Thanks,
Thinh