Hi Felipe,
On 8/20/2018 3:34 AM, Felipe Balbi wrote:
> Gadget driver may take an unbounded amount of time to queue requests
> after XferNotReady. This is important for isochronous endpoints which
> need to be started for a specific (micro-)frame.
>
> Before kicking the transfer, let's check if current frame number is
> still less than our aligned frame number that we got from the
> previous XferNotReady. If it isn't, then we'll increment
> dep->frame_number to make sure it's ahead of current frame number.
>
> Signed-off-by: Felipe Balbi <felipe.ba...@linux.intel.com>
> ---
> drivers/usb/dwc3/core.h | 2 ++
> drivers/usb/dwc3/gadget.c | 11 +++++++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 285ce0ef3b91..3acf8788a680 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -685,6 +685,8 @@ struct dwc3_ep {
> u8 type;
> u8 resource_index;
> u32 frame_number;
> +#define DWC3_EP_FRAME_NUMBER_MASK 0x3fff
> +
> u32 interval;
>
> char name[20];
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index f61a4250c883..0bac9b02f28b 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1257,6 +1257,9 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
>
> static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
> {
> + u16 current_frame_number;
> + u16 frame_number;
> +
> if (list_empty(&dep->pending_list)) {
> dev_info(dep->dwc->dev, "%s: ran out of requests\n",
> dep->name);
> @@ -1265,6 +1268,14 @@ static int __dwc3_gadget_start_isoc(struct dwc3_ep
> *dep)
> }
>
> dep->frame_number = DWC3_ALIGN_FRAME(dep);
> + current_frame_number = __dwc3_gadget_get_frame(dep->dwc);
> + frame_number = dep->frame_number & DWC3_EP_FRAME_NUMBER_MASK;
> +
> + if (frame_number <= current_frame_number) {
This is not right. You're comparing (what should be a 16-bit but masked)
frame_number to a 14-bit current_frame_number.
If the current frame number is 2+ seconds ahead of dep->frame_number,
then this calculation is wrong.
> + dep->frame_number += current_frame_number - frame_number;
> + dep->frame_number = DWC3_ALIGN_FRAME(dep);
> + }
> +
> return __dwc3_gadget_kick_transfer(dep);
> }
>
Thinh
