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Subject[PATCH 34/71] atari_NCR5380: Use arbitration timeout
Allow target selection to fail with a timeout instead of waiting in
infinite loops. This gets rid of the unused NCR_TIMEOUT macro, it is more
defensive and has proved helpful in debugging.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>

---
drivers/scsi/NCR5380.c | 44 ++++++++++++++++++---------------
drivers/scsi/atari_NCR5380.c | 57 ++++++++++++++++++-------------------------
2 files changed, 49 insertions(+), 52 deletions(-)

Index: linux/drivers/scsi/atari_NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/atari_NCR5380.c 2015-11-18 19:33:46.000000000 +1100
+++ linux/drivers/scsi/atari_NCR5380.c 2015-11-18 19:33:47.000000000 +1100
@@ -1406,6 +1406,7 @@ static int NCR5380_select(struct Scsi_Ho
int len;
int err;
unsigned long flags;
+ unsigned long timeout;

NCR5380_dprint(NDEBUG_ARBITRATION, instance);
dprintk(NDEBUG_ARBITRATION, "scsi%d: starting arbitration, id = %d\n", HOSTNO,
@@ -1430,42 +1431,28 @@ static int NCR5380_select(struct Scsi_Ho
NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
NCR5380_write(MODE_REG, MR_ARBITRATE);

- local_irq_restore(flags);
+ /* The chip now waits for BUS FREE phase. Then after the 800 ns
+ * Bus Free Delay, arbitration will begin.
+ */

- /* Wait for arbitration logic to complete */
-#if defined(NCR_TIMEOUT)
- {
- unsigned long timeout = jiffies + 2*NCR_TIMEOUT;
-
- while (!(NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS) &&
- time_before(jiffies, timeout) && !hostdata->connected)
- ;
- if (time_after_eq(jiffies, timeout)) {
- printk("scsi : arbitration timeout at %d\n", __LINE__);
+ local_irq_restore(flags);
+ timeout = jiffies + HZ;
+ while (1) {
+ if (time_is_before_jiffies(timeout)) {
NCR5380_write(MODE_REG, MR_BASE);
- NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
+ shost_printk(KERN_ERR, instance,
+ "select: arbitration timeout\n");
return -1;
}
+ if (!(NCR5380_read(MODE_REG) & MR_ARBITRATE)) {
+ /* Reselection interrupt */
+ return -1;
+ }
+ if (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS)
+ break;
}
-#else /* NCR_TIMEOUT */
- while (!(NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS) &&
- !hostdata->connected)
- ;
-#endif
-
- dprintk(NDEBUG_ARBITRATION, "scsi%d: arbitration complete\n", HOSTNO);
-
- if (hostdata->connected) {
- NCR5380_write(MODE_REG, MR_BASE);
- return -1;
- }
- /*
- * The arbitration delay is 2.2us, but this is a minimum and there is
- * no maximum so we can safely sleep for ceil(2.2) usecs to accommodate
- * the integral nature of udelay().
- *
- */

+ /* The SCSI-2 arbitration delay is 2.4 us */
udelay(3);

/* Check for lost arbitration */
@@ -1628,8 +1615,14 @@ static int NCR5380_select(struct Scsi_Ho
*/

/* Wait for start of REQ/ACK handshake */
- while (!(NCR5380_read(STATUS_REG) & SR_REQ))
- ;
+
+ err = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
+ if (err < 0) {
+ shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
+ NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
+ NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
+ return -1;
+ }

dprintk(NDEBUG_SELECTION, "scsi%d: target %d selected, going into MESSAGE OUT phase.\n",
HOSTNO, cmd->device->id);
Index: linux/drivers/scsi/NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/NCR5380.c 2015-11-18 19:33:46.000000000 +1100
+++ linux/drivers/scsi/NCR5380.c 2015-11-18 19:33:47.000000000 +1100
@@ -1076,6 +1076,7 @@ static int NCR5380_select(struct Scsi_Ho
unsigned char *data;
int len;
int err;
+ unsigned long timeout;

NCR5380_dprint(NDEBUG_ARBITRATION, instance);
dprintk(NDEBUG_ARBITRATION, "scsi%d : starting arbitration, id = %d\n", instance->host_no, instance->this_id);
@@ -1094,28 +1095,31 @@ static int NCR5380_select(struct Scsi_Ho
NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
NCR5380_write(MODE_REG, MR_ARBITRATE);

+ /* The chip now waits for BUS FREE phase. Then after the 800 ns
+ * Bus Free Delay, arbitration will begin.
+ */

- /* We can be relaxed here, interrupts are on, we are
- in workqueue context, the birds are singing in the trees */
spin_unlock_irq(instance->host_lock);
- err = NCR5380_poll_politely(instance, INITIATOR_COMMAND_REG, ICR_ARBITRATION_PROGRESS, ICR_ARBITRATION_PROGRESS, 5*HZ);
- spin_lock_irq(instance->host_lock);
- if (err < 0) {
- printk(KERN_DEBUG "scsi: arbitration timeout at %d\n", __LINE__);
- NCR5380_write(MODE_REG, MR_BASE);
- NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
- return -1;
+ timeout = jiffies + HZ;
+ while (1) {
+ if (time_is_before_jiffies(timeout)) {
+ NCR5380_write(MODE_REG, MR_BASE);
+ shost_printk(KERN_ERR, instance,
+ "select: arbitration timeout\n");
+ spin_lock_irq(instance->host_lock);
+ return -1;
+ }
+ spin_lock_irq(instance->host_lock);
+ if (!(NCR5380_read(MODE_REG) & MR_ARBITRATE)) {
+ /* Reselection interrupt */
+ return -1;
+ }
+ if (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS)
+ break;
+ spin_unlock_irq(instance->host_lock);
}

- dprintk(NDEBUG_ARBITRATION, "scsi%d : arbitration complete\n", instance->host_no);
-
- /*
- * The arbitration delay is 2.2us, but this is a minimum and there is
- * no maximum so we can safely sleep for ceil(2.2) usecs to accommodate
- * the integral nature of udelay().
- *
- */
-
+ /* The SCSI-2 arbitration delay is 2.4 us */
udelay(3);

/* Check for lost arbitration */
@@ -1263,9 +1267,9 @@ static int NCR5380_select(struct Scsi_Ho
spin_unlock_irq(instance->host_lock);
err = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
spin_lock_irq(instance->host_lock);
-
if (err < 0) {
- printk(KERN_ERR "scsi%d: timeout at NCR5380.c:%d\n", instance->host_no, __LINE__);
+ shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
+ NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
return -1;
}



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