linux-kernel - RE: [PATCH] usb: dwc3: gadget:Core consumes a trb software to fill a trb, in ISO

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Date:   Mon, 25 Dec 2017 02:58:42 +0000
From:   Lipengcheng <lpc.li@...ilicon.com>
To:     Felipe Balbi <balbi@...nel.org>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb: dwc3: gadget:Core consumes a trb software to fill
 a trb, in ISO

Hi,

> -----Original Message-----
> From: Felipe Balbi [mailto:balbi@...nel.org]
> Sent: Friday, December 22, 2017 3:54 PM
> To: Lipengcheng
> Cc: linux-usb@...r.kernel.org; linux-kernel@...r.kernel.org; Lipengcheng
> Subject: Re: [PATCH] usb: dwc3: gadget:Core consumes a trb software to fill a trb, in ISO
> 
> 
> Hi,
> 
> Lipengcheng <lpc.li@...ilicon.com> writes:
> 
> > Iso transmission, the current process is that all trb(HWO=1) is handled.
> > Then core generate DWC3_DEPEVT_XFERNOTREADY event, Software begin
> > refill trb, this will produce 0 length package, the patch is to
> > achieve the core consumes a trb, and then the software fill a trb.
> > Normally, there will never be DWC3_DEPEVT_XFERNOTREADY event and 0-length packet.
> >
> > Signed-off-by: l00229106 <lpc.li@...ilicon.com>
> 
> who is 100229106??
Sorry. It is my job number. I will use Pengcheng li to replace it.
> 
> > ---
> >  drivers/usb/dwc3/gadget.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 981fd98..1e6c42e 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -2420,7 +2420,7 @@ static void dwc3_endpoint_transfer_complete(struct dwc3 *dwc,
> >     if (!dep->endpoint.desc)
> >         return;
> >
> > -   if (!usb_endpoint_xfer_isoc(dep->endpoint.desc))
> > +   if (!usb_endpoint_xfer_isoc(dep->endpoint.desc) || (dep->flags &
> > + DWC3_EP_TRANSFER_STARTED))
> 
> this is wrong. isoc endpoints should NEVER be prestarted.
The main purpose is to core handle a trb and sofware re-fill the next trb in the DWC3_DEPEVT_XFERINPROGRESS interrupt. Mayebe it can be modified:
        if (!usb_endpoint_xfer_isoc(dep->endpoint.desc))
                __dwc3_gadget_kick_transfer(dep);
+       else
+               dwc3_prepare_trbs(dep);
+
> 
> --
> balbi