Hi,
On 7/18/2017 4:27 PM, Felipe Balbi wrote:
> Hi,
>
> Manu Gautam <mgautam@xxxxxxxxxxxxxx> writes:
>>> Manu Gautam <mgautam@xxxxxxxxxxxxxx> writes:
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>>> index aea9a5b..b81547d 100644
>>>> --- a/drivers/usb/dwc3/gadget.c
>>>> +++ b/drivers/usb/dwc3/gadget.c
>>>> @@ -854,8 +854,13 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb,
>>>> trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS_FIRST;
>>>>
>>>> if (speed == USB_SPEED_HIGH) {
>>>> - struct usb_ep *ep = &dep->endpoint;
>>>> - trb->size |= DWC3_TRB_SIZE_PCM1(ep->mult - 1);
>>>> + unsigned int maxp = usb_endpoint_maxp(
>>>> + dep->endpoint.desc);
>>>> + unsigned int rem = length % maxp;
>>>> + unsigned int mult = (length / maxp) & 0x3;
>>>> +
>>>> + trb->size |= DWC3_TRB_SIZE_PCM1(
>>>> + rem ? mult : mult - 1);
>>> Manu, It seems to me like we shouldn't be relying on req->length. Which
>>> gadget driver are you using to test this?
>> f_uvc function is used.
>> In bus analyzer logs there are DATA2, DATA1 PIDs even for a 2K byte TRB
>> (also last packet of the video frame are always less than maxpacket size).
> Understood, yeah it makes sense, although I think your patch can be
> simplified. Seems to me that it should be enough to set PCM1 to
> req->length / usb_endpoint_maxp(), no?
Still need to take care of two things:
1. Handle case if If req>length is more than 3K (buggy function driver)
2. We don't need to send extra packet for isoc if length is multiple of maxp.
Hence, remainder must be checked.
> Or, if we want to make use of ep->mult, we could:
>
> unsigned int mult = ep->mult - 1;
>
> if (req->length < (usb_endpoint_maxp() << 1))
> mult--;
I think it should be <=
E.g. for 2k size only two transfers should take place)
> if (req->length < usb_endpoint_maxp())
> mult--;
<=
> trb->size |= DWC3_TRB_SIZE_PCM1(mult);
>
> how about that?
>
This also looks fine and I can send the updated patch.
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