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authorFinn Thain <fthain@telegraphics.com.au>2016-01-03 16:05:19 +1100
committerMartin K. Petersen <martin.petersen@oracle.com>2016-01-06 21:42:55 -0500
commit4d029e9ae9c382b149b16632f49970d8b215e2da (patch)
treeecd48ef21f2f10c7020adebb701952d37b29c4bc /drivers/scsi/g_NCR5380.c
parentcf13b0837d7da2f3dce96e1f364fade13c8648ba (diff)
downloadlinux-4d029e9ae9c382b149b16632f49970d8b215e2da.tar.bz2
ncr5380: Eliminate USLEEP_WAITLONG delay
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>
Diffstat (limited to 'drivers/scsi/g_NCR5380.c')
-rw-r--r--drivers/scsi/g_NCR5380.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index ffbb07b0e9e8..fa9f6d41548b 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -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