Re: [PATCH v3 34/77] atari_NCR5380: Use arbitration timeout

[Hannes Reinecke]

On 12/22/2015 02:18 AM, Finn Thain wrote:

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 

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


Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
--
Dr. Hannes Reinecke   zSeries & Storage
h...@suse.de  +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[PATCH v3 34/77] atari_NCR5380: Use arbitration timeout

[Finn Thain]

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 

---
 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 2015-12-22 12:16:20.0 
+1100
+++ linux/drivers/scsi/atari_NCR5380.c  2015-12-22 12:16:22.0 +1100
@@ -1412,6 +1412,7 @@ 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,
@@ -1436,42 +1437,28 @@ 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 */
@@ -1634,8 +1621,14 @@ 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   2015-12-22 12:16:20.0 +1100
+++ linux/drivers/scsi/NCR5380.c2015-12-22 12:16:22.0 +1100
@@ -1083,6 +1083,7 @@ 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);
@@ -1101,28 +1102,31 @@ 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 

[PATCH v3 34/77] atari_NCR5380: Use arbitration timeout

[Finn Thain]

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 

---
 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 2015-12-22 12:16:20.0 
+1100
+++ linux/drivers/scsi/atari_NCR5380.c  2015-12-22 12:16:22.0 +1100
@@ -1412,6 +1412,7 @@ 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,
@@ -1436,42 +1437,28 @@ 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 */
@@ -1634,8 +1621,14 @@ 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   2015-12-22 12:16:20.0 +1100
+++ linux/drivers/scsi/NCR5380.c2015-12-22 12:16:22.0 +1100
@@ -1083,6 +1083,7 @@ 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);
@@ -1101,28 +1102,31 @@ 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
-   

Re: [PATCH v3 34/77] atari_NCR5380: Use arbitration timeout

[Hannes Reinecke]

On 12/22/2015 02:18 AM, Finn Thain wrote:

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 

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


Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
--
Dr. Hannes Reinecke   zSeries & Storage
h...@suse.de  +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/