Revert "drivers/hwmon/occ: Add temperature fault attribute and VRM temp alarm"

From: "Edward A. James" <[email protected]>

This reverts commit e55423ee10a5057338d24383c00e813436a126ea.

Apologies for pushing this up so early... Userspace applications aren't ready for this change. The hwmon polling application cannot accept EGAIN yet, and we can't be returning apparent errors if the sensor is temporarily unavailable.

Signed-off-by Eddie James <[email protected]>

---
 drivers/hwmon/occ/common.c | 38 +++-----------------------------------
 1 file changed, 3 insertions(+), 35 deletions(-)

drivers/hwmon/occ/common.c +3 -36

index 8ffb556..34002fb 100644
@@ -19,10 +19,6 @@
 #define OCC_EXT_STAT_MEM_THROTTLE      0x20
 #define OCC_EXT_STAT_QUICK_DROP                0x10
 
-#define OCC_TEMP_SENSOR_FAULT          0xFF
-
-#define OCC_FRU_TYPE_VRM               3
-
 atomic_t occ_num_occs = ATOMIC_INIT(0);
 
 struct temp_sensor_1 {

@@ -381,23 +377,11 @@ static ssize_t occ_show_temp_2(struct device *dev,
                val = get_unaligned_be32(&temp->sensor_id);
                break;
        case 1:
-               val = temp->value;
-               if (val == OCC_TEMP_SENSOR_FAULT)
-                       return -EREMOTEIO;
-
-               if (temp->fru_type != OCC_FRU_TYPE_VRM) {
-                       if (val == 0)
-                               return -EAGAIN;
-
-                       val *= 1000;
-               }
+               val = temp->value * 1000;
                break;
        case 2:
                val = temp->fru_type;
                break;
-       case 3:
-               val = temp->value == OCC_TEMP_SENSOR_FAULT;
-               break;
        }
 
        return snprintf(buf, PAGE_SIZE - 1, "%u\n", val);

@@ -796,7 +780,6 @@ static ssize_t occ_show_extended(struct device *dev,
 int occ_setup_sensor_attrs(struct occ *occ)
 {
        unsigned int i, s;
-       struct temp_sensor_2 *temp;
        struct device *dev = occ->bus_dev;
        struct occ_sensors *sensors = &occ->sensors;
        struct occ_attribute *attr;

@@ -816,7 +799,7 @@ int occ_setup_sensor_attrs(struct occ *occ)
                occ->num_attrs += (sensors->temp.num_sensors * 2);
                break;
        case 2:
-               occ->num_attrs += (sensors->temp.num_sensors * 4);
+               occ->num_attrs += (sensors->temp.num_sensors * 3);
                show_temp = occ_show_temp_2;
                break;
        default:

@@ -888,22 +871,13 @@ int occ_setup_sensor_attrs(struct occ *occ)
 
        for (i = 0; i < sensors->temp.num_sensors; ++i) {
                s = i + 1;
-               temp = ((struct temp_sensor_2 *)sensors->temp.data) + i;
 
                snprintf(attr->name, sizeof(attr->name), "temp%d_label", s);
                attr->sensor = OCC_INIT_ATTR(attr->name, 0444, show_temp, NULL,
                                             0, i);
                attr++;
 
-               if (sensors->temp.version > 1 &&
-                   temp->fru_type == OCC_FRU_TYPE_VRM) {
-                       snprintf(attr->name, sizeof(attr->name), "temp%d_alarm",
-                                s);
-               } else {
-                       snprintf(attr->name, sizeof(attr->name), "temp%d_input",
-                                s);
-               }
-
+               snprintf(attr->name, sizeof(attr->name), "temp%d_input", s);
                attr->sensor = OCC_INIT_ATTR(attr->name, 0444, show_temp, NULL,
                                             1, i);
                attr++;

@@ -914,12 +888,6 @@ int occ_setup_sensor_attrs(struct occ *occ)
                        attr->sensor = OCC_INIT_ATTR(attr->name, 0444,
                                                     show_temp, NULL, 2, i);
                        attr++;
-
-                       snprintf(attr->name, sizeof(attr->name), "temp%d_fault",
-                                s);
-                       attr->sensor = OCC_INIT_ATTR(attr->name, 0444,
-                                                    show_temp, NULL, 3, i);
-                       attr++;
                }
        }
 
--

1.8.3.1

Quoted 4 lines · Eddie James

From: "Edward A. James" <[email protected]>

This reverts commit e55423ee10a5057338d24383c00e813436a126ea.

Quoted 4 lines

Apologies for pushing this up so early... Userspace applications aren't ready for this change. The hwmon polling application cannot accept EGAIN yet, and we can't be returning apparent errors if the sensor is temporarily unavailable.

Can you go into some more detail here please.

It looks like these changes are within the hwmon ABI, so userspace that supports hwmon devices shouldn't break.

Cheers,

Joel

Quoted 102 lines

Signed-off-by Eddie James <[email protected]>

---
  drivers/hwmon/occ/common.c | 38 +++-----------------------------------
  1 file changed, 3 insertions(+), 35 deletions(-)

drivers/hwmon/occ/common.c +3 -36

index 8ffb556..34002fb 100644
@@ -19,10 +19,6 @@
  #define OCC_EXT_STAT_MEM_THROTTLE      0x20
  #define OCC_EXT_STAT_QUICK_DROP                0x10
 
-#define OCC_TEMP_SENSOR_FAULT          0xFF
-
-#define OCC_FRU_TYPE_VRM               3
-
  atomic_t occ_num_occs = ATOMIC_INIT(0);
 
  struct temp_sensor_1 {

@@ -381,23 +377,11 @@ static ssize_t occ_show_temp_2(struct device *dev,
                 val = get_unaligned_be32(&temp->sensor_id);
                 break;
         case 1:
-               val = temp->value;
-               if (val == OCC_TEMP_SENSOR_FAULT)
-                       return -EREMOTEIO;
-
-               if (temp->fru_type != OCC_FRU_TYPE_VRM) {
-                       if (val == 0)
-                               return -EAGAIN;
-
-                       val *= 1000;
-               }
+               val = temp->value * 1000;
                 break;
         case 2:
                 val = temp->fru_type;
                 break;
-       case 3:
-               val = temp->value == OCC_TEMP_SENSOR_FAULT;
-               break;
         }
 
         return snprintf(buf, PAGE_SIZE - 1, "%u\n", val);

@@ -796,7 +780,6 @@ static ssize_t occ_show_extended(struct device *dev,
  int occ_setup_sensor_attrs(struct occ *occ)
  {
         unsigned int i, s;
-       struct temp_sensor_2 *temp;
         struct device *dev = occ->bus_dev;
         struct occ_sensors *sensors = &occ->sensors;
         struct occ_attribute *attr;

@@ -816,7 +799,7 @@ int occ_setup_sensor_attrs(struct occ *occ)
                 occ->num_attrs += (sensors->temp.num_sensors * 2);
                 break;
         case 2:
-               occ->num_attrs += (sensors->temp.num_sensors * 4);
+               occ->num_attrs += (sensors->temp.num_sensors * 3);
                 show_temp = occ_show_temp_2;
                 break;
         default:

@@ -888,22 +871,13 @@ int occ_setup_sensor_attrs(struct occ *occ)
 
         for (i = 0; i < sensors->temp.num_sensors; ++i) {
                 s = i + 1;
-               temp = ((struct temp_sensor_2 *)sensors->temp.data) + i;
 
                 snprintf(attr->name, sizeof(attr->name), "temp%d_label", s);
                 attr->sensor = OCC_INIT_ATTR(attr->name, 0444, show_temp, NULL,
                                              0, i);
                 attr++;
 
-               if (sensors->temp.version > 1 &&
-                   temp->fru_type == OCC_FRU_TYPE_VRM) {
-                       snprintf(attr->name, sizeof(attr->name), "temp%d_alarm",
-                                s);
-               } else {
-                       snprintf(attr->name, sizeof(attr->name), "temp%d_input",
-                                s);
-               }
-
+               snprintf(attr->name, sizeof(attr->name), "temp%d_input", s);
                 attr->sensor = OCC_INIT_ATTR(attr->name, 0444, show_temp, NULL,
                                              1, i);
                 attr++;

@@ -914,12 +888,6 @@ int occ_setup_sensor_attrs(struct occ *occ)
                         attr->sensor = OCC_INIT_ATTR(attr->name, 0444,
                                                      show_temp, NULL, 2, i);
                         attr++;
-
-                       snprintf(attr->name, sizeof(attr->name), "temp%d_fault",
-                                s);
-                       attr->sensor = OCC_INIT_ATTR(attr->name, 0444,
-                                                    show_temp, NULL, 3, i);
-                       attr++;
                 }
         }
 
--

1.8.3.1

Quoted 9 lines · Joel Stanley

Quoted 8 lines · Eddie James

From: "Edward A. James" <[email protected]>

This reverts commit e55423ee10a5057338d24383c00e813436a126ea.

Apologies for pushing this up so early... Userspace applications aren't ready for this change. The hwmon polling application cannot accept EGAIN yet, and we can't be returning apparent errors if the sensor is temporarily unavailable.

Quoted 4 lines

Can you go into some more detail here please.

It looks like these changes are within the hwmon ABI, so userspace that supports hwmon devices shouldn't break.

Sure. With this change, the driver returns -EAGAIN when reading temperature sensors that show 0 temperature. Temperature 0 is how the OCC indicates that the sensor is not available at the moment. So, we should retry in a bit. But the hwmon application currently sees any negative errno as an error,

and will not retry on -EAGAIN. So now we get errors when we don't want them (for now), basically.

Thanks,
Eddie

Quoted 15 lines · Eddie James

Quoted 9 lines · Joel Stanley

Quoted 8 lines · Eddie James

From: "Edward A. James" <[email protected]>

This reverts commit e55423ee10a5057338d24383c00e813436a126ea.

Apologies for pushing this up so early... Userspace applications aren't ready for this change. The hwmon polling application cannot accept EGAIN yet, and we can't be returning apparent errors if the sensor is temporarily unavailable.

Quoted 6 lines

Quoted 4 lines

Can you go into some more detail here please.

It looks like these changes are within the hwmon ABI, so userspace that supports hwmon devices shouldn't break.

Sure. With this change, the driver returns -EAGAIN when reading temperature sensors that show 0 temperature. Temperature 0 is how the OCC indicates that the sensor is not available at the moment. So, we should retry in a bit. But the hwmon application currently sees any negative errno as an error,

Actually the userspace retries for a configurable period on eio, etimedout, ebadmsg, eagain, and exnio. It also exits cleanly on enoent.

If any of these errnos don’t go away after the configured number of retry attempts, an error is logged. Any other errnos and an error is logged immediately. If this list needs improvement I’d love to hear about it.

ebadmsg and enxio are observed when i2c devices are unplugged with transfers in various stages of flight. They occur just before the driver is unbound after the presence gpio toggle on these devices is noticed and processed (killing the hwmon userspace daemon cleanly).

eio, etimedout seem to be bus type errors that appear somewhat infrequently, but occur nevertheless.

we all know what eagain means…

It isn’t so much that the hwmon userspace doesn’t support this change, its just the resulting behavior difference at the other end of the hwmon abi <-> dbus api translation is not optimal, right now.

1 - Without this change, the hwmon userspace reads a value of 0 out of the sysfs attribute and happily reports that as the temp at the DBus level.

With this change, the hwmon userspace would read the attribute, get an error and retry for a bit. After a number of retries, the error is logged and the sensor is marked faulted at a dbus level.

The issue is the consumer of the sensor at the dbus level. Today, the dbus consumer happens to translate the sensor value of zero into the desired behavior. If we submit this change the sensor will be put into faulted state and the consuming application doesn’t have support for that yet.

We have open issues to enhance the application to support faulted sensors, its just not implemented yet.

I hope this helps a decision to be made.