diff options
| author | Finn Thain <fthain@telegraphics.com.au> | 2016-10-10 00:46:52 -0400 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2016-11-08 17:29:47 -0500 |
| commit | d4408dd7ecff6ed3561f155923738474c585f31d (patch) | |
| tree | d5b2e08ec4d80487519d6016ad329ae551b52dd5 /drivers/scsi/NCR5380.c | |
| parent | abd12b09292cc87a75f7c3e3c3f2b12589560bb1 (diff) | |
| download | linux-d4408dd7ecff6ed3561f155923738474c585f31d.tar.bz2 | |
scsi: ncr5380: Simplify register polling limit
When polling a device register under irq lock the polling loop terminates
after a given number of jiffies. Make this timeout independent of the HZ
setting.
All 5380 drivers benefit from this patch, which optimizes the PIO fast
path, because they all use PIO transfers (for phases other than DATA IN
and DATA OUT). Some cards support only PIO transfers (even for DATA
phases). CPU cycles are scarce on some of these systems, so a small
improvement here makes a big difference.
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>
Diffstat (limited to 'drivers/scsi/NCR5380.c')
| -rw-r--r-- | drivers/scsi/NCR5380.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c index 790babc5ef66..c5c15573e23f 100644 --- a/drivers/scsi/NCR5380.c +++ b/drivers/scsi/NCR5380.c @@ -200,13 +200,9 @@ static int NCR5380_poll_politely2(struct Scsi_Host *instance, int reg2, int bit2, int val2, int wait) { struct NCR5380_hostdata *hostdata = shost_priv(instance); + unsigned long n = hostdata->poll_loops; unsigned long deadline = jiffies + wait; - unsigned long n; - /* Busy-wait for up to 10 ms */ - n = min(10000U, jiffies_to_usecs(wait)); - n *= hostdata->accesses_per_ms; - n /= 2000; do { if ((NCR5380_read(reg1) & bit1) == val1) return 0; @@ -482,6 +478,7 @@ static int NCR5380_init(struct Scsi_Host *instance, int flags) struct NCR5380_hostdata *hostdata = shost_priv(instance); int i; unsigned long deadline; + unsigned long accesses_per_ms; instance->max_lun = 7; @@ -530,7 +527,8 @@ static int NCR5380_init(struct Scsi_Host *instance, int flags) ++i; cpu_relax(); } while (time_is_after_jiffies(deadline)); - hostdata->accesses_per_ms = i / 256; + accesses_per_ms = i / 256; + hostdata->poll_loops = NCR5380_REG_POLL_TIME * accesses_per_ms / 2; return 0; } |