[1/4] usb: dwc3: gadget: return errors from __dwc3_gadget_start_isoc()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Felipe,

Thank you for the patch.

On Monday, 20 August 2018 13:29:58 EEST Felipe Balbi wrote:
> Sometimes, errors happen when kicking transfers from
> __dwc3_gadget_start_isoc(). In those cases, we need to pass along the
> error so gadget driver can make informed decisions.
> 
> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
> ---
>  drivers/usb/dwc3/gadget.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 69bf137aab37..f61a4250c883 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1255,17 +1255,17 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
> return DWC3_DSTS_SOFFN(reg);
>  }
> 
> -static void __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
> +static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
>  {
>  	if (list_empty(&dep->pending_list)) {
>  		dev_info(dep->dwc->dev, "%s: ran out of requests\n",
>  				dep->name);
>  		dep->flags |= DWC3_EP_PENDING_REQUEST;
> -		return;
> +		return -EAGAIN;
>  	}
> 
>  	dep->frame_number = DWC3_ALIGN_FRAME(dep);
> -	__dwc3_gadget_kick_transfer(dep);
> +	return __dwc3_gadget_kick_transfer(dep);
>  }
> 
>  static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request
> *req) @@ -1306,8 +1306,7 @@ static int __dwc3_gadget_ep_queue(struct
> dwc3_ep *dep, struct dwc3_request *req)
> 
>  		if ((dep->flags & DWC3_EP_PENDING_REQUEST)) {
>  			if (!(dep->flags & DWC3_EP_TRANSFER_STARTED)) {
> -				__dwc3_gadget_start_isoc(dep);
> -				return 0;
> +				return __dwc3_gadget_start_isoc(dep);

Do I understandand correctly that the new -EAGAIN error returned above when an 
underrun has occurred will never be returned here, as we call 
__dwc3_gadget_start_isoc() after adding a request to the pending_list, covered 
by the same spinlock that is taken by the IRQ handler to remove requests from 
the list ? I don't think that's an issue, but I want to make sure nothing is 
overlooked.

>  			}
>  		}
>  	}
> @@ -2427,7 +2426,7 @@ static void
> dwc3_gadget_endpoint_transfer_not_ready(struct dwc3_ep *dep, const struct
> dwc3_event_depevt *event)
>  {
>  	dwc3_gadget_endpoint_frame_from_event(dep, event);
> -	__dwc3_gadget_start_isoc(dep);
> +	(void) __dwc3_gadget_start_isoc(dep);

No need for a cast here.

>  }
> 
>  static void dwc3_endpoint_interrupt(struct dwc3 *dwc,