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

[Felipe Balbi]

Hi,

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:

#!/usr/bin/env ruby

$errors = 0
$success = 0
$total = 0

$initial_size = 64
$max_size = 8 * 1024 * 1024 # 8MiB
$current_size = $initial_size

def create_file(size)
  `dd if=/dev/zero of=file.bin bs=#{size} count=1 > /dev/null 2>&1`
end

def send_file(size)
  `dfu-util -v -d 8087:0a99 -D file.bin > /dev/null 2>&1`
end

def transmit(size)
  create_file(size)
  send_file(size)
end

def transmit_and_check(size)
  transmit(size)

  if $?.success?
       $success += 1
       print "."
  else
       $errors += 1
       print "F"
  end

  $total += 1
end

while $current_size <= $max_size do
  transmit_and_check($current_size - 1)
  transmit_and_check($current_size)
  transmit_and_check($current_size + 1)

  $current_size *= 2
end

puts "\n"
puts "Test Done"
puts "Successes: #{$success}"
puts "Failures:  #{$errors}"
puts "Total:     #{$total}"

-- 
balbi
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