From: Alan Chandler <alan@chandlerfamily.org.uk>
To: linux-kernel@vger.kernel.org, axboe@suse.de
Subject: ide-cd problem
Date: Sat, 20 Nov 2004 18:42:14 +0000 [thread overview]
Message-ID: <200411201842.15091.alan@chandlerfamily.org.uk> (raw)
I have been trying to track down why all attempts to burn a cd on my ide cdrw
fails (see bug #3741 on bugzilla ), with a subprocess of cdrecord ending up
hanging in uninterruptable sleep state.
I think I understand what is happening, I just don't know what to do about it.
Inside drivers/ide/ide-cd.c
the ide_do_rw_cdrom routine has been called via a request with the request
flags having the REQ_BLOCK_PC flag set. The request->data_len of this
request is set to 0.
This request is sent to the device and it generates interrupts to eventually
land it up inside the routine cdrom_newpc_intr.
At this point the status register on the hardware is set to 0x58 - implying, I
think that the DRQ_STAT bit is set and that something should be sent to the
device.
Normally, because the requested data_len is not zero, the data is sent. In
this case however, because the original request had nothing to send, the
while/if clauses to initiate a new transfer are skipped and the routine ends
up setting a new interrupt handler address and returning to await an
interrupt that will never come.
Question: should something validate that the request length is not zero
earlier, or should there be a check in ide-cd.c, or is it my hardware (its a
generic cd read/rewriter which announces itself as 'CW078D CD-R/RW')
--
Alan Chandler
alan@chandlerfamily.org.uk
First they ignore you, then they laugh at you,
then they fight you, then you win. --Gandhi
next reply other threads:[~2004-11-20 18:42 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-20 18:42 Alan Chandler [this message]
2004-11-20 19:47 ` ide-cd problem Jens Axboe
2004-11-21 0:53 ` Alan Chandler
2004-11-21 8:56 ` Jens Axboe
2004-11-21 10:25 ` Alan Chandler
2004-11-21 16:13 ` Alan Chandler
2004-11-22 7:52 ` Alan Chandler
2004-11-22 8:01 ` Jens Axboe
2004-11-22 10:30 ` Alan Chandler
2004-11-22 10:51 ` Jens Axboe
2004-11-22 11:29 ` Alan Chandler
2004-11-22 11:31 ` Jens Axboe
2004-11-22 12:53 ` Alan Chandler
2004-11-22 13:02 ` Jens Axboe
2004-11-22 19:19 ` Alan Chandler
2004-11-22 23:48 ` Alan Chandler
2004-11-23 7:13 ` Alan Chandler
2004-11-23 14:51 ` Jens Axboe
2004-11-23 21:49 ` Alan Chandler
2004-11-26 23:39 ` Alan Chandler
2004-11-29 17:29 ` Bill Davidsen
2004-11-30 8:59 ` Alan Chandler
2004-12-10 21:32 ` ide-cd problem revisited - more brainpower needed Alan Chandler
2004-12-10 23:14 ` Alan Cox
2004-12-12 0:17 ` Alan Chandler
2004-12-12 11:39 ` Alan Cox
2004-12-12 13:34 ` Alan Chandler
2004-12-14 0:20 ` Alan Chandler
2004-12-16 15:56 ` Bill Davidsen
2004-12-17 23:59 ` Alan Chandler
2004-11-24 23:19 ` ide-cd problem Alan Cox
2004-11-25 15:29 ` Jens Axboe
2004-11-25 16:25 ` Alan Cox
2004-11-25 18:12 ` Jens Axboe
2004-11-25 18:45 ` Alan Chandler
2004-11-23 18:34 ` Jeff Garzik
2004-11-23 19:13 ` Jens Axboe
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