linux-kernel - Re: [PATCH 2/3] phy: da8xx-usb: Configure CFGCHIP2 to support OTG workaround

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Message-ID: <cfaba8e3-7024-c9f7-bb4e-ab71ab256833@lechnology.com>
Date:   Tue, 25 Oct 2016 14:16:55 -0500
From:   David Lechner <david@...hnology.com>
To:     Alexandre Bailon <abailon@...libre.com>, khilman@...libre.com,
        b-liu@...com, balbi@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH 2/3] phy: da8xx-usb: Configure CFGCHIP2 to support OTG
 workaround

On 10/25/2016 08:52 AM, Alexandre Bailon wrote:
> If we configure the da8xx OTG phy in OTG mode, neither device or host
> mode will work. That is because the PHY is not able to detect and notify
> the driver that value of ID pin changed.
> To work despite this hardware limitation, the da8xx glue implement a
> workaround.
> But to work, the workaround require the VBUS sense and the session end
> comparator to enabled.
> Enable them if the phy is configured in OTG mode.
>
> Signed-off-by: Alexandre Bailon <abailon@...libre.com>
> ---
>  drivers/phy/phy-da8xx-usb.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/phy/phy-da8xx-usb.c b/drivers/phy/phy-da8xx-usb.c
> index 32ae78c..fd39292 100644
> --- a/drivers/phy/phy-da8xx-usb.c
> +++ b/drivers/phy/phy-da8xx-usb.c
> @@ -93,24 +93,31 @@ static int da8xx_usb20_phy_power_off(struct phy *phy)
>  static int da8xx_usb20_phy_set_mode(struct phy *phy, enum phy_mode mode)
>  {
>  	struct da8xx_usb_phy *d_phy = phy_get_drvdata(phy);
> +	int ret;
>  	u32 val;
>
> +	ret = regmap_read(d_phy->regmap, CFGCHIP(2), &val);
> +	if (ret)
> +		return ret;
> +
> +	val &= ~CFGCHIP2_OTGMODE_MASK;
> +
>  	switch (mode) {
>  	case PHY_MODE_USB_HOST:		/* Force VBUS valid, ID = 0 */
> -		val = CFGCHIP2_OTGMODE_FORCE_HOST;
> +		val |= CFGCHIP2_OTGMODE_FORCE_HOST;
>  		break;
>  	case PHY_MODE_USB_DEVICE:	/* Force VBUS valid, ID = 1 */
> -		val = CFGCHIP2_OTGMODE_FORCE_DEVICE;
> +		val |= CFGCHIP2_OTGMODE_FORCE_DEVICE;
>  		break;
>  	case PHY_MODE_USB_OTG:	/* Don't override the VBUS/ID comparators */
> -		val = CFGCHIP2_OTGMODE_NO_OVERRIDE;
> +		val |= CFGCHIP2_OTGMODE_NO_OVERRIDE |
> +			CFGCHIP2_SESENDEN | CFGCHIP2_VBDTCTEN;

Do we need to clear CFGCHIP2_SESENDEN and/or CFGCHIP2_VBDTCTEN in case 
PHY_MODE_USB_HOST: or case PHY_MODE_USB_DEVICE:? Or are they ignored in 
those modes?

>  		break;
>  	default:
>  		return -EINVAL;
>  	}
>
> -	regmap_write_bits(d_phy->regmap, CFGCHIP(2), CFGCHIP2_OTGMODE_MASK,
> -			  val);
> +	regmap_write(d_phy->regmap, CFGCHIP(2), val);
>
>  	return 0;
>  }
>