sane-project-website/old-archive/1999-06/0189.html

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<title>sane-devel: Re: Umax 1200S on LinuxPPC R5</title>
<h1>Re: Umax 1200S on LinuxPPC R5</h1>
<b>Tom Martone</b> (<a href="mailto:tommartone@erols.com"><i>tommartone@erols.com</i></a>)<br>
<i>Wed, 23 Jun 1999 22:03:20 -0400</i>
<p>
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Oliver Rauch wrote:<br>
<i>&gt; </i><br>
<i>&gt; Simon Piette wrote:</i><br>
<i>&gt; </i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; &gt; export SANE_DEBUG_UMAX=10</i><br>
<i>&gt; &gt; &gt; and then call (x)scanimage</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; OK. Here is the output. We're going foward: It's says "handled as DEVICE</i><br>
<i>&gt; &gt; BUSY!" Should I recompile the kernel with SCSI GENERIC as a module,</i><br>
<i>&gt; &gt; instead of built-in?</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; [</i><br>
<i>&gt; &gt; [umax] check condition sense handler</i><br>
<i>&gt; &gt; [umax] invalid sense key =&gt; handled as DEVICE BUSY!</i><br>
<i>&gt; &gt; [umax] check condition sense handler</i><br>
<i>&gt; &gt; [umax] invalid sense key =&gt; handled as DEVICE BUSY!</i><br>
<i>&gt; &gt; [umax] attach_scanner: scanner-identification failed</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; </i><br>
<i>&gt; It looks like the umax backend is not able to get an inuiry</i><br>
<i>&gt; from the scanner.</i><br>
<i>&gt; </i><br>
<i>&gt; Are you able to use other scsi-devices via the generic scsi driver</i><br>
<i>&gt; on your computer?</i><br>
<i>&gt; </i><br>
<i>&gt; Bye</i><br>
<i>&gt; Oliver</i><br>
Greetings,<br>
<p>
I've been following this discussion a bit and took a look at the<br>
sense_handler code and then took a look a the Linux SCSI Programmers<br>
HOWTO and then the SCSI-2 ansi spec.<br>
<p>
The code:<br>
  if ( get_RS_error_code(result) != 0x70 ) <br>
  { <br>
    DBG(DBG_proc, "invalid sense key =&gt; handled as DEVICE BUSY!\n");<br>
    return SANE_STATUS_DEVICE_BUSY;							    /* sense key invalid */<br>
  }<br>
perhaps is being a bit too restrictive.  According to the SCSI spec,<br>
it seems that 0x71 is a valid value as well.  0x70 is a current error<br>
and 0x71 is a deferred error.  Perhaps this is the value that Simon <br>
is getting?  It would be real helpful if we could dump out the sense<br>
buffer :)<br>
<p>
I've also seen similar code written as:<br>
  if ( result[0] &amp; 0x80 )<br>
  {<br>
     /* sense buffer invalid */<br>
     return SANE_STATUS_GOOD;<br>
  }<br>
That code is checking the "valid bit" talked about in the SCSI spec<br>
snippet I've included below.  Then it returns the _GOOD status if<br>
it is not set (maybe this is too liberal??)<br>
<p>
I hope that this is helpful.  I must admit that I find scsi error <br>
handling quite confusing myself.  I'd like to see how this one gets<br>
resolved.<br>
<p>
Thanks,<br>
Tom Martone<br>
<p>
<i>&gt;From the SCSI-2 spec...</i><br>
<p>
            Table 7-35: Error Codes 70h and 71h Sense Data Format<br>
<p>
==============================================================================<br>
  Bit|   7    |   6    |   5    |   4    |   3    |   2    |   1    |   0    |<br>
Byte |        |        |        |        |        |        |        |        |<br>
==============================================================================<br>
 0   | Valid  |                  Error Code (70h or 71h)                     |<br>
-----|-----------------------------------------------------------------------|<br>
 1   |                           Segment Number                              |<br>
-----|-----------------------------------------------------------------------|<br>
 2   |Filemark|  EOM   |  ILI   |Reserved|         Sense Key                 |<br>
-----|-----------------------------------------------------------------------|<br>
 3   | (MSB)                                                                 |<br>
- - -|- -                        Information                              - -|<br>
 6   |                                                                 (LSB) |<br>
-----|-----------------------------------------------------------------------|<br>
 7   |                           Additional Sense Length (n-7)               |<br>
-----|-----------------------------------------------------------------------|<br>
 8   | (MSB)                                                                 |<br>
- - -|- -                        Command-Specific Information             - -|<br>
 11  |                                                                 (LSB) |<br>
-----|-----------------------------------------------------------------------|<br>
 12  |                           Additional Sense Code                       |<br>
-----|-----------------------------------------------------------------------|<br>
 13  |                           Additional Sense Code Qualifier             |<br>
-----|-----------------------------------------------------------------------|<br>
 14  |                           Field Replaceable Unit Code                 |<br>
-----|-----------------------------------------------------------------------|<br>
15 to|  SKSV  |                                                              |<br>
- - -|---------- -               Sense-Key Specific                       - -|<br>
 17  |                                                                       |<br>
-----|-----------------------------------------------------------------------|<br>
18 to|                                                                       |<br>
- - -|- -                        Additional Sense Bytes                   - -|<br>
 n   |                                                                       |<br>
==============================================================================<br>
<p>
<p>
  A valid bit of zero indicates that the information field is not as defined <br>
in this standard.  A valid bit of one indicates the information field contains <br>
valid information as defined in this standard.  Targets shall implement the <br>
valid bit.<br>
<p>
  The sense data format for error codes 70h (current errors) and 71h (deferred <br>
errors) are defined in Table 7-35.  Error code values of 72h to 7Eh are <br>
reserved.  Error code 7Fh is for a vendor-specific sense data format.  Targets <br>
shall implement error code 70h; implementation of error code 71h is optional. <br>
Error code values of 00h to 6Fh are not defined by this standard and their use <br>
is not recommended.<br>
<p>
<p>
<pre>
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</pre>
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<p>
<ul>
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<li> <b>Next message:</b> <a href="0190.html">Remmert: "New Camera"</a>
<li> <b>Previous message:</b> <a href="0188.html">David Mosberger-Tang: "Re: Umax 1200S on LinuxPPC R5"</a>
<li> <b>Maybe in reply to:</b> <a href="0140.html">Simon Piette: "Umax 1200S on LinuxPPC R5"</a>
<!-- nextthread="start" -->
<li> <b>Next in thread:</b> <a href="0192.html">Oliver Rauch: "Re: Umax 1200S on LinuxPPC R5"</a>
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