HI,
On Fri, Oct 24, 2014 at 10:14:19AM +0900, Anton Tikhomirov wrote:
>
> Hi,
>
> On Thu, 23 Oct 2014, Alan Stern wrote:
> > On Thu, 23 Oct 2014, Felipe Balbi wrote:
> >
> > > here's v2:
> > >
> > > 8<--------------------------------------------------------------
> > >
> > > From 1080b54d66e3e77410b41732e76746ed8e2c01c7 Mon Sep 17 00:00:00
> > 2001
> > > From: Felipe Balbi <balbi@xxxxxx>
> > > Date: Tue, 30 Sep 2014 10:39:14 -0500
> > > Subject: [PATCH] usb: dwc3: ep0: fix Data Phase for transfer sizes
> > aligned to
> > > wMaxPacketSize
> > >
> > > According to Section 8.5.3.2 of the USB 2.0 specification,
> > > a USB device must terminate a Data Phase with either a
> > > short packet or a ZLP (if the previous transfer was
> > > a multiple of wMaxPacketSize).
> > >
> > > For reference, here's what the USB 2.0 specification, section
> > > 8.5.3.2 says:
> > >
> > > "
> > > 8.5.3.2 Variable-length Data Stage
> > >
> > > A control pipe may have a variable-length data phase
> > > in which the host requests more data than is contained
> > > in the specified data structure. When all of the data
> > > structure is returned to the host, the function should
> > > indicate that the Data stage is ended by returning a
> > > packet that is shorter than the MaxPacketSize for the
> > > pipe. If the data structure is an exact multiple of
> > > wMaxPacketSize for the pipe, the function will return
> > > a zero-length packet to indicate the end of the Data
> > > stage.
> > > "
> > >
> > > Signed-off-by: Felipe Balbi <balbi@xxxxxx>
> > > ---
> > > drivers/usb/dwc3/ep0.c | 19 +++++++++++++------
> > > 1 file changed, 13 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> > > index a47cc1e..ce6b0c7 100644
> > > --- a/drivers/usb/dwc3/ep0.c
> > > +++ b/drivers/usb/dwc3/ep0.c
> > > @@ -828,12 +828,19 @@ static void dwc3_ep0_complete_data(struct dwc3
> > *dwc,
> > >
> > > dwc3_ep0_stall_and_restart(dwc);
> > > } else {
> > > - /*
> > > - * handle the case where we have to send a zero packet.
> > This
> > > - * seems to be case when req.length > maxpacket. Could it
> > be?
> > > - */
> > > - if (r)
> > > - dwc3_gadget_giveback(ep0, r, 0);
> > > + dwc3_gadget_giveback(ep0, r, 0);
> >
> > Don't you want to wait until the ZLP has completed before doing the
> > giveback?
> >
> > In fact, shouldn't all this ZLP code run when the transfer is
> > submitted, rather than when it completes? The idea is that you get a
> > request, you queue up all the necessary TRBs or whatever, and if an
> > extra ZLP is needed then you queue up an extra TRB.
>
> You may want to check my patch one more time. I sent it for review 10
> monthes ago:
>
> [PATCH] usb: dwc3: ep0: Handle variable-length Data Stage
>
> It works just fine for us in our custom kernel.
you also said you'd send another version (see [1]) and never did. 10
months passed and I had even forgotten about this issue until I decided
to run all gadget drivers through USB[23]0CV and found that g_ncm falls
into this same bug, so I wrote the patch above.
considering you never sent another version even after 10 months, I'll
just go ahead with this one and work on improving TRB handling on this
driver so that when req->zero is true we can actually allocate a
separate TRB (as has been discussed on this and previous threads).
I'll add a note to commit log stating that you provided the original
patch but failed to provide a follow up.
[1] http://www.spinics.net/lists/linux-usb/msg99809.html
--
balbi
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