linux-kernel - Re: [PATCH v3 5/5] usb: musb: da8xx: Remove set

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Date:   Thu, 3 Nov 2016 12:18:53 -0500
From:   David Lechner <david@...hnology.com>
To:     Alexandre Bailon <abailon@...libre.com>, b-liu@...com,
        balbi@...nel.org
Cc:     kishon@...com, khilman@...libre.com, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, nsekhar@...com
Subject: Re: [PATCH v3 5/5] usb: musb: da8xx: Remove set_mode callback

On 11/03/2016 10:26 AM, Alexandre Bailon wrote:
> The USB PHY is able to operate in OTG, host or peripheral.
> Some board may be wired to work act only as host or peripheral.
> In such case, the dr_mode property of controller must be set to
> host or peripheral. But doing that will also configure the PHY
> in host or peripheral mode whereas OTG is able to detect which
> role the USB controller should take.
> The PHY's host or peripheral mode are actually only useful when
> hardware doesn't allow OTG to detect it's role.
>
> The set_mode callback is used by the musb driver to set mode
> of the PHY. But in the case of DA8xx, the PHY have some issues.
> The OTG mode work correctly but the host and peripheral don't.
> In host mode, the PHY stops to work after the first disconnect.
> In device mode, the PHY doesn't detect any disconnect.
> As the OTG mode is working properly, let the PHY in OTG mode,
> whatever is the controller mode.
>
> Signed-off-by: Alexandre Bailon <abailon@...libre.com>
> ---
>  drivers/usb/musb/da8xx.c | 23 -----------------------
>  1 file changed, 23 deletions(-)
>
> diff --git a/drivers/usb/musb/da8xx.c b/drivers/usb/musb/da8xx.c
> index 6749aa1..581f830 100644
> --- a/drivers/usb/musb/da8xx.c
> +++ b/drivers/usb/musb/da8xx.c
> @@ -335,28 +335,6 @@ static irqreturn_t da8xx_musb_interrupt(int irq, void *hci)
>  	return ret;
>  }
>
> -static int da8xx_musb_set_mode(struct musb *musb, u8 musb_mode)

Bin suggested using some sort of quirks flag. So instead of removing 
this callback, I think this is where to incorporate the quirks flags.

I suppose the quirks could be kernel config options. Perhaps someone 
else has a better idea?

> -{
> -	struct da8xx_glue *glue = dev_get_drvdata(musb->controller->parent);
> -	enum phy_mode phy_mode;
> -
> -	switch (musb_mode) {
> -	case MUSB_HOST:		/* Force VBUS valid, ID = 0 */
> -		phy_mode = PHY_MODE_USB_HOST;

this should be something like...

		phy_mode = force_host_mode_quirk ? PHY_MODE_USB_HOST
					 	 : PHY_MODE_USB_OTG;


> -		break;
> -	case MUSB_PERIPHERAL:	/* Force VBUS valid, ID = 1 */
> -		phy_mode = PHY_MODE_USB_DEVICE;

and...

		phy_mode = force_peripheral_mode_quirk ?
				PHY_MODE_USB_DEVICE : PHY_MODE_USB_OTG;


> -		break;
> -	case MUSB_OTG:		/* Don't override the VBUS/ID comparators */
> -		phy_mode = PHY_MODE_USB_OTG;
> -		break;
> -	default:
> -		return -EINVAL;
> -	}
> -
> -	return phy_set_mode(glue->phy, phy_mode);
> -}
> -
>  static int da8xx_musb_init(struct musb *musb)
>  {
>  	struct da8xx_glue *glue = dev_get_drvdata(musb->controller->parent);
> @@ -445,7 +423,6 @@ static const struct musb_platform_ops da8xx_ops = {
>  	.enable		= da8xx_musb_enable,
>  	.disable	= da8xx_musb_disable,
>
> -	.set_mode	= da8xx_musb_set_mode,
>  	.try_idle	= da8xx_musb_try_idle,
>
>  	.set_vbus	= da8xx_musb_set_vbus,
>