[v3,2/2] usb: dwc3: gadget: Report isoc transfer frame number

[Felipe Balbi <balbi@kernel.org>]

Hi,

Thinh Nguyen <thinh.nguyen@synopsys.com> writes:
> Implement the new frame_number API to report the isochronous interval
> frame number. This patch checks and reports the interval in which the
> isoc transfer was transmitted or received via the Isoc-First TRB SOF
> number field.
>
> Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
> ---
> Change in v3:
> - Implement the change with the redefined frame_number meaning
> Change in v2:
> - Capture frame number at request cleanup
>
>  drivers/usb/dwc3/core.h   |  1 +
>  drivers/usb/dwc3/gadget.c | 13 +++++++++++++
>  2 files changed, 14 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index ed0359d1216d..2c9f7a93147a 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -777,6 +777,7 @@ enum dwc3_link_state {
>  #define DWC3_TRB_CTRL_ISP_IMI		BIT(10)
>  #define DWC3_TRB_CTRL_IOC		BIT(11)
>  #define DWC3_TRB_CTRL_SID_SOFN(n)	(((n) & 0xffff) << 14)
> +#define DWC3_TRB_CTRL_GET_SID_SOFN(n)	(((n) & (0xffff << 14)) >> 14)
>  
>  #define DWC3_TRBCTL_TYPE(n)		((n) & (0x3f << 4))
>  #define DWC3_TRBCTL_NORMAL		DWC3_TRB_CTRL_TRBCTL(1)
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 679c12e14522..2de563124fc1 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2254,6 +2254,19 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
>  	if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
>  		trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
>  
> +	/*
> +	 * For isochronous transfers, the first TRB in a service interval must
> +	 * have the Isoc-First type. Track and report its interval frame number.
> +	 */
> +	if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
> +	    (trb->ctrl & DWC3_TRBCTL_ISOCHRONOUS_FIRST)) {
> +		unsigned int frame_number;
> +
> +		frame_number = DWC3_TRB_CTRL_GET_SID_SOFN(trb->ctrl);
> +		frame_number &= ~(dep->interval - 1);
> +		req->request.frame_number = frame_number;
> +	}

could you refresh my memory on how this is going to be used?