linux-kernel - Re: [PATCH] usb: cdns3: gadget: Fix g_audio use case when connected to Super-Speed host

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Message-ID: <20191030063636.GE26815@b29397-desktop>
Date:   Wed, 30 Oct 2019 06:36:47 +0000
From:   Peter Chen <peter.chen@....com>
To:     Roger Quadros <rogerq@...com>
CC:     "felipe.balbi@...ux.intel.com" <felipe.balbi@...ux.intel.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "pawell@...ence.com" <pawell@...ence.com>,
        "nsekhar@...com" <nsekhar@...com>,
        "kurahul@...ence.com" <kurahul@...ence.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: cdns3: gadget: Fix g_audio use case when connected
 to Super-Speed host

On 19-10-29 17:15:14, Roger Quadros wrote:
> Take into account gadget driver's speed limit when programming
> controller speed.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
> Hi Greg,
> 
> Please apply this for -rc.
> Without this, g_audio is broken on cdns3 USB controller is
> connected to a Super-Speed host.
> 
> cheers,
> -roger
> 
>  drivers/usb/cdns3/gadget.c | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
> index 40dad4e8d0dc..1c724c20d468 100644
> --- a/drivers/usb/cdns3/gadget.c
> +++ b/drivers/usb/cdns3/gadget.c
> @@ -2338,9 +2338,35 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget,
>  {
>  	struct cdns3_device *priv_dev = gadget_to_cdns3_device(gadget);
>  	unsigned long flags;
> +	enum usb_device_speed max_speed = driver->max_speed;
>  
>  	spin_lock_irqsave(&priv_dev->lock, flags);
>  	priv_dev->gadget_driver = driver;
> +
> +	/* limit speed if necessary */
> +	max_speed = min(driver->max_speed, gadget->max_speed);
> +
> +	switch (max_speed) {
> +	case USB_SPEED_FULL:
> +		writel(USB_CONF_SFORCE_FS, &priv_dev->regs->usb_conf);
> +		writel(USB_CONF_USB3DIS, &priv_dev->regs->usb_conf);
> +		break;
> +	case USB_SPEED_HIGH:
> +		writel(USB_CONF_USB3DIS, &priv_dev->regs->usb_conf);
> +		break;
> +	case USB_SPEED_SUPER:
> +		break;
> +	default:
> +		dev_err(priv_dev->dev,
> +			"invalid maximum_speed parameter %d\n",
> +			max_speed);
> +		/* fall through */
> +	case USB_SPEED_UNKNOWN:
> +		/* default to superspeed */
> +		max_speed = USB_SPEED_SUPER;
> +		break;
> +	}
> +
>  	cdns3_gadget_config(priv_dev);
>  	spin_unlock_irqrestore(&priv_dev->lock, flags);
>  	return 0;
> @@ -2570,12 +2596,7 @@ static int cdns3_gadget_start(struct cdns3 *cdns)
>  	/* Check the maximum_speed parameter */
>  	switch (max_speed) {
>  	case USB_SPEED_FULL:
> -		writel(USB_CONF_SFORCE_FS, &priv_dev->regs->usb_conf);
> -		writel(USB_CONF_USB3DIS, &priv_dev->regs->usb_conf);
> -		break;
>  	case USB_SPEED_HIGH:
> -		writel(USB_CONF_USB3DIS, &priv_dev->regs->usb_conf);
> -		break;
>  	case USB_SPEED_SUPER:
>  		break;
>  	default:

Just a small comment:

You could delete switch-case at cdns3_gadget_start, and just use
if() statement, eg:

	max_speed = usb_get_maximum_speed(cdns->dev);
	if (max_speed == USB_SPEED_UNKNOWN)
		max_speed = USB_SPEED_SUPER;

Otherwise:

Acked-by: Peter Chen <peter.chen@....com>

-- 

Thanks,
Peter Chen