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scsi: ncr5380: Increase register polling limit

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If NCR5380_poll_politely() is called under irq lock, the polling time
limit is clamped to avoid a spike in interrupt latency. When not under
irq lock, the same polling time limit acts as the worst case delay
between schedule() calls.

During PDMA (under irq lock) I've found that the 10 ms time limit is
sometimes too short, and leads to the error message,
sd 0:0:0:0: [sda] tag#1 macscsi_pread: !REQ and !ACK

This particular target identifies itself as a QUANTUM DAYTONA514S. It
seems to be slower to assert ACK than the other targets I've tested.
This patch solves the problem by increasing the polling timeout.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Finn Thain 2016-10-10 00:46:52 -04:00 committed by Martin K. Petersen
parent d4408dd7ec
commit 4822827a69
1 changed files with 1 additions and 1 deletions
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2
drivers/scsi/NCR5380.h
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@ -253,7 +253,7 @@ struct NCR5380_cmd {
#define NCR5380_PIO_CHUNK_SIZE 256
/* Time limit (ms) to poll registers when IRQs are disabled, e.g. during PDMA */
#define NCR5380_REG_POLL_TIME 10
#define NCR5380_REG_POLL_TIME 15
static inline struct scsi_cmnd *NCR5380_to_scmd(struct NCR5380_cmd *ncmd_ptr)
{