Hi Felipe, > > Hi Lukasz, > > Lukasz Majewski <lu...@denx.de> writes: > > Hi Felipe, > > > > Thanks for the patch. > > Please see my comments below. > > > > On 13 Feb 2017 11:42 am, Felipe Balbi > > <felipe.ba...@linux.intel.com> wrote: > > > > Hi, > > > > Marek Vasut <ma...@denx.de> writes: > > > On 02/10/2017 05:32 PM, Andy Shevchenko wrote: > > >> From: Felipe Balbi <felipe.ba...@linux.intel.com> > > >> > > >> If last packet is short, we shouldn't write req->length bytes > > >> to non-volatile media, we should write only what's available to > > >> us, which is held in req->actual. > > >> > > >> Signed-off-by: Felipe Balbi <felipe.ba...@linux.intel.com> > > >> Signed-off-by: Andy Shevchenko > > >> <andriy.shevche...@linux.intel.com> > > > > > > Since I have no clue about DFU internals, I will wait for > > > Lukasz's Ack. > > > > you don't need to have any clues about DFU internals to realise > > that this fixes an actual bug, see below: > > > > I don't know your exact use case. Please keep in mind that we most > > eMMC :-)
Ok.
>
> > work on NAND and eMMC, which require the whole block write.
>
> Well, then the file should have been padded already before sending it
> over USB, right? :-)
>
> You shouldn't write req->length if you don't receive req->length as
> you are, potentially, writing garbage to the storage medium :-)
Yes. Correct....
>
> > However, I will setup test environment (after changing the job it
> > was gone), test your patch and then let you know.
>
> cool
>
> > >> 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 :-)
Best regards,
Lukasz Majewski
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