On 08/25/2014 07:22 PM, Jassi Brar wrote:
> On Mon, Aug 25, 2014 at 9:30 PM, Daniel Mack <zonque@xxxxxxxxx> wrote:
>> @@ -187,7 +189,7 @@ agdev_iso_complete(struct usb_ep *ep, struct usb_request *req)
>>
>> if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>> src = prm->dma_area + prm->hw_ptr;
>> - req->actual = req->length;
>> + req->length = req->actual = uac2->c_pktsize;
>>
> This doesn't seem right.
> We asked req->length to be transmitted by the udc which shouldn't
> return until that is done. So at this point setting 'length' doesn't
> mean much. The original assignment to 'actual' is only because we want
> to ignore any issue that caused the udc to transmit fewer bytes (we
> drop that data).
Looking at this again, setting req->length is in fact the right thing to
do. We want to prepare a new packet of a specific length, so we have to
let the udc driver know how much data is contains before we call
usb_ep_queue() again.
Note that this is for SNDRV_PCM_STREAM_PLAYBACK, so for the IN endpoint
of the gadget. Reading your description again makes me believe you
actually wanted to do that for the *capture* side, because this is were
could possibly 'drop data', right?
Daniel
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