Re: SCSI scanner problem with all kernels since 2.3.42

From: Juergen E Fischer (fischer@linux-buechse.de)
Date: Mon Jan 15 2001 - 16:24:35 EST


Hi Doug,

On Tue, Jan 09, 2001 at 03:53:02PM -0500, Douglas Gilbert wrote:
> There is also a problem report with the SnapScan 1236 <--> aha152x
> combination also based on SANE 1.0.3 . This one is looking
> like an "uninitialized errno" bug fixed in SANE 1.0.4 .

This should be solved with the attached patch. As you might remember
it's the same problem we already discussed with Abel Deuring.

Normally there should be no need to use REQUEST SENSE from outside,
when the driver supports auto-sense. It should be wrong as devices are
required to clear the sense data after the first, automatically issued
REQUEST SENSE. BTW the new eh code requires low-level drivers to do
auto-sense. The driver assumed that these are wrong and ignores them.
This behaviour was adopted from the aha1542 driver.

But for the SnapScan REQUEST SENSE is not only used on CHECK CONDITION,
but also to request the warmup time. Therefore the REQUEST SENSE is
valid here and proves the assumption wrong for such devices.

Even more worse is that the driver returned SUCCESS instead of 0 on
REQUEST SENSE. That's plain wrong and apparently tells the mid-level
code not to queue any more commands.

The warmup time issue with the SnapScan (and maybe other devices) should
also apply to the aha1542 driver.

Juergen

-- 
Juergen E Fischer


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