Hi Felipe,
>
> Hi Lukasz,
>
> Lukasz Majewski <lu...@denx.de> writes:
> >> > >> drivers/usb/gadget/f_dfu.c | 2 +-
> >> > >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >> > >>
> >> > >> diff --git a/drivers/usb/gadget/f_dfu.c
> >> > >> b/drivers/usb/gadget/f_dfu.c index 8e7c981657..64cdfa7c98
> >> > >> 100644 --- a/drivers/usb/gadget/f_dfu.c
> >> > >> +++ b/drivers/usb/gadget/f_dfu.c
> >> > >> @@ -159,7 +159,7 @@ static void
> >> > >> dnload_request_complete(struct usb_ep *ep, struct
> >> > >> usb_request *req) int ret;
> >> > >>
> >> > >> ret = dfu_write(dfu_get_entity(f_dfu->altsetting), req->buf,
> >> > >> - req->length, f_dfu->blk_seq_num);
> >> > >> + req->actual, f_dfu->blk_seq_num);
> >> >
> >> > DFU driver queues a request to USB controller. Per the gadget
> >> > API req->length contains maximum amount of data to be
> >> > transmitted. req->actual is written by USB controller with the
> >> > actual amount of data that we transmitted.
> >> >
> >> > In the case of IN (TX), upon completion req->length and
> >> > req->actual should always be equal (unless errors show up, etc)
> >> >
> >> > In the case of OUT (RX), upon completion req->actual MAY BE less
> >> > than req->length and that's not an error. Say host sent us a
> >> > short packet which causes early termination of transfer.
> >> >
> >> > With that in mind, let's consider the situation where we're
> >> > receiving data from host using DFU. Let's assume that we have a
> >> > 4096 byte buffer for transfers and we're receiving a binary
> >> > that's 7679 bytes in size.
> >> >
> >> > Here's what we will do (pseudo-code):
> >> >
> >> > int remaining = 7679;
> >> > char buf[4096];
> >> >
> >> > while (remaining) {
> >> > req->length = 4096;
> >> > req->buf = buf;
> >> > usb_ep_queue(req);
> >> >
> >> > /* wait for completion */
> >> >
> >> > remaining -= req->actual;
> >> >
> >> > dfu_write(buf, req->length); /* this is the error */
> >> > }
> >> >
> >> > Can you see here that in the last packet we will write 4096
> >> > bytes when we should write only 3583?
> >> >
> >> > In principle you are right. I need to check if this change will
> >> > not introduce regressions.
> >> >
> >> > Can you share your use case?
> >>
> >> Intel Edison running v2017.03-rc1 + patches (see [1]), flashing
> >> u-boot.bin over DFU (see [2] for details). Without $subject, image
> >> has to be aligned to 4096 bytes as below:
> >>
> >> $ dd if=u-boot.bin of=u-boot-4k.bin bs=4k seek=1 && truncate -s
> >> %4096 u-boot-4k.bin
> >>
> >> With $subject, I don't need truncate. We still need the 4096 byte
> >> of zeroes in the beginning of the image for other reasons (which I
> >> really don't know why at this point).
> >>
> >> [1] https://github.com/andy-shev/u-boot/tree/edison
> >> [2] https://communities.intel.com/message/435516#435516
> >>
> >
> > Ok. I will check this. Thanks for pointing out :-)
>
> Any updates here? I'd like to send Tangier Soc and Intel Edison Board
> support but I kinda depend on this patch making upstream. I can resend
> as part of the "add intel edison" series.
>
> Let me knowI'm setting up /test/py/dfu now on BBB. I will let you know by EOD. > Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
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