Re: [PATCH 2/2] usb: dwc2: fix isoc split in transfer with no data

[wlf]

Dear Sergei,


å 2018å04æ24æ 16:27, Sergei Shtylyov åé:
> Hello!
>
> On 4/24/2018 5:43 AM, William Wu wrote:
>
> > If isoc split in transfer with no data (the length of DATA0
> > packet is 0), we can't simply return immediately. Because the
> > DATA0 can be the first transaction or the second transaction for
> > the isoc split in transaction. If the DATA0 packet with on data
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^^ no?
Thank you for correcting me. I will fix it in next patch version.
> > is in the first transaction, we can return immediately. But if
> > the the DATA0 packet with on data is in the second transaction
>
> Â One "the" too many. And that "on data" again... :-)
Ah, sorry to make such a simple mistake. I will fix these in next patch 
version.
> > of isoc split in transaction sequence, we need to increase the
> > qtd->isoc_frame_index and giveback urb to device driver if needed,
> > otherwise, the MDATA packet will be lost.
> >
> > A typical test case is that connect the dwc2 controller with an
> > usb hs Hub (GL852G-12), and plug an usb fs audio device (Plantronics
> > headset) into the downstream port of Hub. Then use the usb mic
> > to record, we can find noise when playback.
> >
> > In the case, the isoc split in transaction sequence like this:
> >
> > - SSPLIT IN transaction
> > - CSPLIT IN transaction
> > ÂÂ - MDATA packet (176 bytes)
> > - CSPLIT IN transaction
> > ÂÂ - DATA0 packet (0 byte)
> >
> > This patch use both the length of DATA0 and qtd->isoc_split_offset
> > to check if the DATA0 is in the second transaction.
> >
> > Signed-off-by: William Wu <william.wu@xxxxxxxxxxxxxx>
> [...]
>
> MBR, Sergei
Best regards,
ÂÂÂ wulf
>