Re: plextor px-708uf: cannot get disk type
>From: Andy Polyakov <appro@fy.chalmers.se>
>> >> I have a Plextor PX-708UF (USB 2.0) on a Red Hat Linux 9 machine.
>> >>
>> >> cdrecord.prodvd: Input/output error. read disk info: scsi sendcmd: no error
>> >> CDB: 51 00 00 00 00 00 00 00 24 00
>> > ^^ I don't know if following holds true
>> >for other USB implementations, but Linux USB is very picky about
>>
>> First: Cdrecord added support to circumvent Linux USB DMA Bugs about
>> 3.5 years ago.
>If I wanted to imply that cdrecord doesn't circumvent USB bugs/specifics
>I would have written "that's because cdrecord apparently ..." It wrote
>nothing of that sort!!! I wrote "structure is 32 bytes upon media load,
>which must be the cause for the trouble."
And the Plextor says (upon request) that the strucure is 0x22 + 2 byte header
>> This happens, if you run the command with a DVD+R medium while
>> the Kernel SCSI transport is working correctly to the Plextor 708:
>>
>> Executing 'read disk info' command on Bus 0 Target 0, Lun 0 timeout 240s
>> CDB: 51 00 00 00 00 00 00 00 24 00
>> cmd finished after 0.000s timeout 240s
>> Got 36 (0x24), expecting 36 (0x24) bytes of data.
>> Received Data: 00 22 00 01 01 01 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 23 05 40 00 00 00 00 00 00 00 00 00 00 00 00
>Is it output from requestor's system? If not is it USB connected unit?
>But in either case given this new evidence, I have to admit that I might
>be wrong and it might turn out to be a firmware bug or pecularity... MMC
>drafts are specific about length of this structure being 32+8*n. So that
>the reported length is indeed bogus... Well, one has all rights to
>disregard bogus values... A.
This is from a Plextor 708 (as I wrote.....)
Even if the Plextor had a firmware bug and returns less, then
USB should not create the problems that may only be a result of a DMA
_overrun_.
Jörg
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