[U-Boot] [PATCH v1] usb: gadget: f_dfu: write req->actual bytes

[Lukasz Majewski]

Hi Felipe,

> 
> Hi,
> 
> Lukasz Majewski <lukma at denx.de> writes:
> >> Lukasz Majewski <lukma at denx.de> writes:
> >> >> Lukasz Majewski <lukma at 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 know
> >> >
> >> > I'm setting up /test/py/dfu now on BBB. I will let you know by
> >> > EOD.
> >> 
> >> Here's what I used for testing:
> >
> > I do appreciate that you tested it - even better, that with
> > different approach.
> >
> > However, some time ago Stephen Warren has rewritten tests for DFU,
> > UMS to use some python infrastructure. Those tests (especially DFU,
> > test corner cases - ZLP, +/-1B to packet size, etc).
> 
> that's exactly what I tested :-)
> 
> > If you want, you can add your board to them.
> 
> I'll see how to do that and maybe add to the TODO list
> 

Acked-by: Lukasz Majewski <lukma at denx.de>

Tested-by: Lukasz Majewski <lukma at denx.de>

Test HW: BBB (am335x) - with tests/py/dfu

I've added your patch to u-boot-dfu tree. I will send PR tomorrow.

You may also want to look into patches from Patrick Delaunay (those
also will be added to PR):

http://patchwork.ozlabs.org/patch/704131/
http://patchwork.ozlabs.org/patch/706492/
http://patchwork.ozlabs.org/patch/706493/



Best regards,

Lukasz Majewski

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