[sane-devel] deadlock with sanei_usb_read_bulk

[m. allan noah]

excellent work. please keep us informed.

allan

On 2/10/08, Jürgen Ernst <jrernst at gmx.de> wrote:
> Hi!
> I managed to solve the problem.
> Here it is:
> Canon driver sends a dummy bulk write as shown in the log. It only
> produces errors and I think it's only for delaying bulk reads. We can
> omit that and use a fix delay of 1 ms instead.
> Sanei_USB sets the right endpoints. I can read and write data on
> endpoint 0. It's all as it should be. Now initializing scanner and
> reading buttons is working. Getting access to scandata is following.
>
> Jürgen Ernst wrote:
> > Hi!
> >
> > I'm trying to write the backend for Canon LiDE 600F and now I'm stuck
> > with sanei_usb_read_bulk. I tried 10 hours but I don't understand how to
> > get sanei_usb working with bulk_read. Can somebody help me out?
> >
> > Here are some details:
> >
> > Canon LiDE 600F is similar to Canon LiDE 70. I checked this with two
> > guys owning a LiDE 70. So you can read some info on
> > http://www.sane-project.org/unsupported/canon-lide-70.html
> >
> > ...
> > <endpoint 0>
> >    bEndpointAddress  0x02 (out 0x02)
> >    bmAttributes      2 (bulk)
> > ...
> > <endpoint 0>
> >    bEndpointAddress  0x83 (in 0x03)
> >    bmAttributes      2 (bulk)
> > ...
> >
> > For short:
> > LiDE 600F has only two endpoints. Both bulk no interrupt. In the log
> > file no control messages are used. Only simple bulk read and write.
> >
> > I programmed a perl script with which I was able to access the scanner
> > and retrieve scan data.
> >
> > So this was the point to start writing the sane backend in C.
> >
> > Okay, let's look first on a perl code snippet:
> >
> > sub canon_get
> > {
> >    my ( $reg ) = @_ ;
> >    my $data = '01 ' . $reg . ' 01 00' ;
> >    my $err = $dev->bulk_write(hex('02'), hex2bin($data), $timeout);
> >
> >    my $data = "\0" x 512 ;
> >    my $cnt = $dev->bulk_write(hex('03'), $data, $timeout);
> >
> >    my $data = ' ' ;
> >    my $cnt = $dev->bulk_read(hex('83'), $data, 1, $timeout) ;
> >    return ( $data ) ;
> > }
> >
> > This is the procedure to get 1 byte of data from the CP2155 chip.
> > Suppose we called canon_get('91'); then $reg is '91' in hex.
> > $data is set to '01 91 01 00'.
> > I made it this way to better check with output from log.
> > hex2bin converts this string to binary.
> >
> > Then a first bulk_write is made. In perl I had to give the
> > bEndpointAddress '02' while in sanei_usb I saw I had to give the
> > endpoint number as an integer (endpoint 0).
> >
> > Second is a dummy write on the other endpoint (endpoint 1) with 512
> > bytes of data.
> >
> > Third we can get the result with a 1 byte bulk_read on endpoint 1.
> >
> > That's it.
> >
> > But it doesn't work in sane.
> >
> > Here's the snippet of my test procedure in C:
> >
> > static byte setup_buffer[] = { 0, 0, 0, 0, ... ,0 };
> >
> > static SANE_Status
> > CP2155get (CP2155_Register reg, byte *data)
> > {
> >    SANE_Status status;
> >    size_t count;
> >
> >    setup_buffer[0] = 0x01;
> >    setup_buffer[1] = (reg) & 0xFF;
> >    setup_buffer[2] = 0x01;
> >    setup_buffer[3] = 0x00;
> >    count = 4;
> >
> >    status = sanei_usb_write_bulk (0, setup_buffer, &count);
> >
> >    if (status != SANE_STATUS_GOOD)
> >      DBG (1, "CP2155get: sanei_usb_write_bulk.1 error\n");
> >
> >    count = 512;
> >    status = sanei_usb_write_bulk (0, setup_buffer, &count);
> >
> >    if (status != SANE_STATUS_GOOD)
> >      DBG (1, "CP2155get: sanei_usb_write_bulk.2 error\n");
> >
> >    count = 1;
> >    status = sanei_usb_read_bulk (0, data, &count);
> >
> >    if (status != SANE_STATUS_GOOD)
> >      DBG (1, "CP2155get: sanei_usb_read_bulk error\n");
> >
> >    return status;
> > }
> >
> > setup_buffer is an array with 512 bytes.
> >
> > The first two bulk_writes didn't return any error.
> > It seems that they worked fine.
> >
> > On the last bulk_read the program hangs forever.
> >
> > I surely did a mistake but I don't know where and why.
> > Please help.
>
>
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