I have some TEAC DV-28E-V CDROM drives that after polling for status
starts to timeout requests (the time it takes to do this varies between
5mins and 24hrs).
I believe only an APATPI reset gets them out of this timeout behaviour.
I assume this is down to bad firmware/hardware (the latest firmware has
been applied).
I happens on multiply drives of this version.
BUT...
The problem is that even when the requests timeout the ioctl
CDROM_DRIVE_STATUS will receive a status of CDS_DISC_OK.
This is obviously not the correct status (particularly when there is no
CD disc in the drive).
I have added some instrumentation to the code and this is the general
stack flow I see:
In the interrupt handler:
do_ide_request()
ide_do_request()
start_request() returns ide_stopped
ide_wait_stat() returns -EBUSY
ide_error() returns ide_stopped + stat=0xD0 {Busy}
ide_dump_status() returns 0 (so err=0)
rq->errors = 1;
ide_end_drive_cmd(err) b/c err is 0, then sets rq->errors=0
In the ioctl:
ide_cdrom_drive_status() Returns CDS_DISC_OK
cdrom_check_status() Returns 0.
ide_cd_queue_pc() Ignores the return from blk_execute_rq(). Checks for the flag REQ_FAILED in rq->cmd_flags (which is not set). Returns 0.
blk_execute_rq() Since rq->errors==1 and then returns 0
wait_for_completion()
The problem seems to be that in ide_cd_queue_pc():
1) the error return from blk_execute_rq() is ignored
2) the REQ_FAILED in rq->cmd_flags is not set in the interrupt handler (which is what ide_cd_queue_pc() seems to be concerned about)
Anyone have any comments:
1) why in ide_dump_status() a stat of BUSY_STAT does not translate to an error return ?
2) Is setting rq->cmd_flags |= REQ_FAILED in ide_wait_stat() an acceptable way to solve issue.
Patch something like this...
Index: linux/drivers/ide/ide-iops.c
===================================================================
--- linux.orig/drivers/ide/ide-iops.c 2010-07-20 15:37:01.871300665 +0100
+++ linux/drivers/ide/ide-iops.c 2010-07-28 11:43:21.386752993 +0100
@@ -652,6 +657,9 @@ int ide_wait_stat(ide_startstop_t *start
if (err) {
char *s = (err == -EBUSY) ? "status timeout" : "status error";
*startstop = ide_error(drive, s, stat);
+
+ if (err == -EBUSY)
+ rq->cmd_flags |= REQ_FAILED;
}
return err;
I appreciate any pointers you can give
Thanks
dom
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