[U-Boot] [PATCH 2/6] usb: dwc2: Handle NAK during CONTROL DATA and STATUS stage

[Marek Vasut <marex@denx.de>]

On Sunday, December 13, 2015 at 05:17:54 AM, Stefan Br?ns wrote:
> A function is allowed to return NAKs during the DATA stage to control
> data flow control. NAKs during the STATUS stage signal the function
> is still processing the request.
> 
> Signed-off-by: Stefan Br?ns <stefan.bruens@rwth-aachen.de>
> ---
>  drivers/usb/host/dwc2.c | 37 ++++++++++++++++++++++++-------------
>  1 file changed, 24 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
> index 5ef6deb..db3acd4 100644
> --- a/drivers/usb/host/dwc2.c
> +++ b/drivers/usb/host/dwc2.c
> @@ -892,8 +892,8 @@ static int _submit_control_msg(struct dwc2_priv *priv,
> struct usb_device *dev, {
>  	int devnum = usb_pipedevice(pipe);
>  	int pid, ret, act_len;
> -	/* For CONTROL endpoint pid should start with DATA1 */
>  	int status_direction;
> +	unsigned long timeout;
> 
>  	if (devnum == priv->root_hub_devnum) {
>  		dev->status = 0;
> @@ -907,26 +907,37 @@ static int _submit_control_msg(struct dwc2_priv
> *priv, struct usb_device *dev, if (ret)
>  		return ret;
> 
> +	timeout = get_timer(0) + USB_TIMEOUT_MS(pipe);
>  	if (buffer) {
> +		/* DATA stage */
>  		pid = DWC2_HC_PID_DATA1;
> -		ret = chunk_msg(priv, dev, pipe, &pid, usb_pipein(pipe), buffer,
> -				len, false);
> +		act_len = 0;
> +		do {
> +			if (get_timer(0) > timeout) {
> +				printf("Timeout during CONTROL DATA stage\n");
> +				return -ETIMEDOUT;
> +			}
> +			ret = chunk_msg(priv, dev, pipe, &pid, usb_pipein(pipe),
> +					buffer, len, false);
> +			act_len += dev->act_len;
> +			buffer += dev->act_len;
> +			len -= dev->act_len;
> +		} while (len && (ret == -EAGAIN));

I can't say I'm a big fan of these conditions ^ . Can you rework a bit so it's
more obvious what the code does ? The condition in the while (cond) is really
inobvious at a first glance.

>  		if (ret)
>  			return ret;
> -		act_len = dev->act_len;
> -	} /* End of DATA stage */
> -	else
> +		status_direction = usb_pipeout(pipe);
> +	} else {
> +		/* No-data CONTROL always ends with an IN transaction */
> +		status_direction = 1;
>  		act_len = 0;
> +	}

Otherwise:
Acked-by: Marek Vasut <marex@denx.de>