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ncr5380: Eliminate USLEEP_WAITLONG delay

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Linux 2.1.105 introduced the USLEEP_WAITLONG delay, apparently "needed for
Mustek scanners". It is intended to stall the issue queue for 5 seconds.
There are a number of problems with this.

1. Only g_NCR5380 enables the delay, which implies that the other five
   drivers using the NCR5380.c core driver remain incompatible with
   Mustek scanners.

2. The delay is not implemented by atari_NCR5380.c, which is problematic
   for re-unifying the two core driver forks.

3. The delay is implemented using NCR5380_set_timer() which makes it
   unreliable. A new command queued by the mid-layer cancels the delay.

4. The delay is applied indiscriminately in several situations in which
   NCR5380_select() returns -1. These are-- reselection by the target,
   failure of the target to assert BSY, and failure of the target to
   assert REQ. It's clear from the comments that USLEEP_WAITLONG is not
   relevant to the reselection case. And reportedly, these scanners do
   not disconnect.

5. atari_NCR5380.c was forked before Linux 2.1.105, so it was spared some
   of the damage done to NCR5380.c. In this case, the atari_NCR5380.c core
   driver was more standard-compliant and may not have needed any
   workaround like the USLEEP_WAITLONG kludge. The compliance issue was
   addressed in the previous patch.

If these scanners still don't work, we need a better solution. Retrying
selection until EH aborts a command offers equivalent robustness. Bugs in
the existing driver prevent EH working correctly but this is addressed in
a subsequent patch. Remove USLEEP_WAITLONG.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Finn Thain 2016-01-03 16:05:19 +11:00 committed by Martin K. Petersen
parent cf13b0837d
commit 4d029e9ae9
2 changed files with 5 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/scsi/NCR5380.c
View File

@ -468,10 +468,6 @@ static void NCR5380_print_phase(struct Scsi_Host *instance)
#ifndef USLEEP_POLL
#define USLEEP_POLL msecs_to_jiffies(200)
#endif
#ifndef USLEEP_WAITLONG
/* RvC: (reasonable time to wait on select error) */
#define USLEEP_WAITLONG USLEEP_SLEEP
#endif
/*
* Function : int should_disconnect (unsigned char cmd)
@ -619,8 +615,8 @@ static void prepare_info(struct Scsi_Host *instance)
"can_queue %d, cmd_per_lun %d, "
"sg_tablesize %d, this_id %d, "
"flags { %s%s%s%s}, "
#if defined(USLEEP_POLL) && defined(USLEEP_WAITLONG)
"USLEEP_POLL %lu, USLEEP_WAITLONG %lu, "
#if defined(USLEEP_POLL) && defined(USLEEP_SLEEP)
"USLEEP_POLL %lu, USLEEP_SLEEP %lu, "
#endif
"options { %s} ",
instance->hostt->name, instance->io_port, instance->n_io_port,
@ -631,8 +627,8 @@ static void prepare_info(struct Scsi_Host *instance)
hostdata->flags & FLAG_DTC3181E ? "DTC3181E " : "",
hostdata->flags & FLAG_NO_PSEUDO_DMA ? "NO_PSEUDO_DMA " : "",
hostdata->flags & FLAG_TOSHIBA_DELAY ? "TOSHIBA_DELAY " : "",
#if defined(USLEEP_POLL) && defined(USLEEP_WAITLONG)
USLEEP_POLL, USLEEP_WAITLONG,
#if defined(USLEEP_POLL) && defined(USLEEP_SLEEP)
USLEEP_POLL, USLEEP_SLEEP,
#endif
#ifdef AUTOPROBE_IRQ
"AUTOPROBE_IRQ "
@ -1030,15 +1026,10 @@ static void NCR5380_main(struct work_struct *work)
if (!NCR5380_select(instance, tmp)) {
/* OK or bad target */
} else {
/* RvC: device failed, so we wait a long time
this is needed for Mustek scanners, that
do not respond to commands immediately
after a scan */
printk(KERN_DEBUG "scsi%d: device %d did not respond in time\n", instance->host_no, tmp->device->id);
LIST(tmp, hostdata->issue_queue);
tmp->host_scribble = (unsigned char *) hostdata->issue_queue;
hostdata->issue_queue = tmp;
NCR5380_set_timer(hostdata, USLEEP_WAITLONG);
done = 0;
}
} /* if hostdata->selecting */
if (hostdata->connected

1
drivers/scsi/g_NCR5380.c
View File

@ -59,7 +59,6 @@
/* settings for DTC3181E card with only Mustek scanner attached */
#define USLEEP_POLL msecs_to_jiffies(10)
#define USLEEP_SLEEP msecs_to_jiffies(200)
#define USLEEP_WAITLONG msecs_to_jiffies(5000)
#define AUTOPROBE_IRQ