* [PATCH] hwmon: mcp9982: Add external diode fault read
@ 2026-04-22 8:43 Victor Duicu
2026-04-22 11:38 ` Guenter Roeck
2026-04-22 12:10 ` sashiko-bot
0 siblings, 2 replies; 3+ messages in thread
From: Victor Duicu @ 2026-04-22 8:43 UTC (permalink / raw)
To: Guenter Roeck; +Cc: linux-hwmon, linux-kernel, victor.duicu, marius.cristea
This patch adds external diode fault read capability
to the MCP998X/33 and MCP998XD/33D driver.
Signed-off-by: Victor Duicu <victor.duicu@microchip.com>
---
drivers/hwmon/mcp9982.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/drivers/hwmon/mcp9982.c b/drivers/hwmon/mcp9982.c
index 26c69e3388ab..2e75ade20118 100644
--- a/drivers/hwmon/mcp9982.c
+++ b/drivers/hwmon/mcp9982.c
@@ -92,19 +92,19 @@ static const struct hwmon_channel_info * const mcp9985_info[] = {
HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
- HWMON_T_CRIT_HYST,
+ HWMON_T_CRIT_HYST | HWMON_T_FAULT,
HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
- HWMON_T_CRIT_HYST,
+ HWMON_T_CRIT_HYST | HWMON_T_FAULT,
HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
- HWMON_T_CRIT_HYST,
+ HWMON_T_CRIT_HYST | HWMON_T_FAULT,
HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
- HWMON_T_CRIT_HYST),
+ HWMON_T_CRIT_HYST | HWMON_T_FAULT),
HWMON_CHANNEL_INFO(chip,
HWMON_C_UPDATE_INTERVAL),
NULL
@@ -510,6 +510,18 @@ static int mcp9982_read(struct device *dev, enum hwmon_sensor_types type, u32 at
*val -= hyst * 1000;
+ return 0;
+ case hwmon_temp_fault:
+ /*
+ * Because the ALERT/THERM pin is set in Therm(Comparator)
+ * mode, the external diode fault status register
+ * does not clear the bits after reading.
+ */
+ *val = regmap_test_bits(priv->regmap, MCP9982_EXT_FAULT_STATUS_ADDR,
+ BIT(channel));
+ if (*val < 0)
+ return *val;
+
return 0;
default:
return -EINVAL;
@@ -681,6 +693,7 @@ static umode_t mcp9982_is_visible(const void *_data, enum hwmon_sensor_types typ
case hwmon_temp_max_alarm:
case hwmon_temp_max_hyst:
case hwmon_temp_crit_alarm:
+ case hwmon_temp_fault:
return 0444;
case hwmon_temp_min:
case hwmon_temp_max:
---
base-commit: fb447217c59a13b2fff22d94de2498c185cd9032
change-id: 20260422-add-external-diode-fault-read-a0c3cd1a4761
Best regards,
--
Victor Duicu <victor.duicu@microchip.com>
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] hwmon: mcp9982: Add external diode fault read
2026-04-22 8:43 [PATCH] hwmon: mcp9982: Add external diode fault read Victor Duicu
@ 2026-04-22 11:38 ` Guenter Roeck
2026-04-22 12:10 ` sashiko-bot
1 sibling, 0 replies; 3+ messages in thread
From: Guenter Roeck @ 2026-04-22 11:38 UTC (permalink / raw)
To: Victor Duicu; +Cc: linux-hwmon, linux-kernel, marius.cristea
On 4/22/26 01:43, Victor Duicu wrote:
> This patch adds external diode fault read capability
> to the MCP998X/33 and MCP998XD/33D driver.
>
> Signed-off-by: Victor Duicu <victor.duicu@microchip.com>
> ---
> drivers/hwmon/mcp9982.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hwmon/mcp9982.c b/drivers/hwmon/mcp9982.c
> index 26c69e3388ab..2e75ade20118 100644
> --- a/drivers/hwmon/mcp9982.c
> +++ b/drivers/hwmon/mcp9982.c
> @@ -92,19 +92,19 @@ static const struct hwmon_channel_info * const mcp9985_info[] = {
> HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
> HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
> HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
> - HWMON_T_CRIT_HYST,
> + HWMON_T_CRIT_HYST | HWMON_T_FAULT,
> HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
> HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
> HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
> - HWMON_T_CRIT_HYST,
> + HWMON_T_CRIT_HYST | HWMON_T_FAULT,
> HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
> HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
> HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
> - HWMON_T_CRIT_HYST,
> + HWMON_T_CRIT_HYST | HWMON_T_FAULT,
> HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_MIN |
> HWMON_T_MIN_ALARM | HWMON_T_MAX | HWMON_T_MAX_ALARM |
> HWMON_T_MAX_HYST | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
> - HWMON_T_CRIT_HYST),
> + HWMON_T_CRIT_HYST | HWMON_T_FAULT),
> HWMON_CHANNEL_INFO(chip,
> HWMON_C_UPDATE_INTERVAL),
> NULL
> @@ -510,6 +510,18 @@ static int mcp9982_read(struct device *dev, enum hwmon_sensor_types type, u32 at
>
> *val -= hyst * 1000;
>
> + return 0;
> + case hwmon_temp_fault:
> + /*
> + * Because the ALERT/THERM pin is set in Therm(Comparator)
> + * mode, the external diode fault status register
> + * does not clear the bits after reading.
> + */
What does that mean ? How does this behavior differ from other alarm
bits to warrant that comment ?
Thanks,
Guenter
> + *val = regmap_test_bits(priv->regmap, MCP9982_EXT_FAULT_STATUS_ADDR,
> + BIT(channel));
> + if (*val < 0)
> + return *val;
> +
> return 0;
> default:
> return -EINVAL;
> @@ -681,6 +693,7 @@ static umode_t mcp9982_is_visible(const void *_data, enum hwmon_sensor_types typ
> case hwmon_temp_max_alarm:
> case hwmon_temp_max_hyst:
> case hwmon_temp_crit_alarm:
> + case hwmon_temp_fault:
> return 0444;
> case hwmon_temp_min:
> case hwmon_temp_max:
>
> ---
> base-commit: fb447217c59a13b2fff22d94de2498c185cd9032
> change-id: 20260422-add-external-diode-fault-read-a0c3cd1a4761
>
> Best regards,
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] hwmon: mcp9982: Add external diode fault read
2026-04-22 8:43 [PATCH] hwmon: mcp9982: Add external diode fault read Victor Duicu
2026-04-22 11:38 ` Guenter Roeck
@ 2026-04-22 12:10 ` sashiko-bot
1 sibling, 0 replies; 3+ messages in thread
From: sashiko-bot @ 2026-04-22 12:10 UTC (permalink / raw)
To: Victor Duicu; +Cc: linux-hwmon
Sashiko AI review found 1 potential issue(s):
- [Medium] Reading the `hwmon_temp_fault` attribute in Standby mode returns stale data because it fails to trigger a one-shot conversion.
--
commit 50b760776977e57ad65e2996d0bfd4a793fe2276
Author: Victor Duicu <victor.duicu@microchip.com>
hwmon: mcp9982: Add external diode fault read
This patch adds external diode fault read capability to the MCP998X/33
and MCP998XD/33D driver.
> diff --git a/drivers/hwmon/mcp9982.c b/drivers/hwmon/mcp9982.c
> index 26c69e3388ab8..2e75ade20118b 100644
> --- a/drivers/hwmon/mcp9982.c
> +++ b/drivers/hwmon/mcp9982.c
[ ... ]
> @@ -510,6 +510,18 @@ static int mcp9982_read(struct device *dev, enum hwmon_sensor_types type, u32 at
>
> *val -= hyst * 1000;
>
> + return 0;
> + case hwmon_temp_fault:
> + /*
> + * Because the ALERT/THERM pin is set in Therm(Comparator)
> + * mode, the external diode fault status register
> + * does not clear the bits after reading.
> + */
> + *val = regmap_test_bits(priv->regmap, MCP9982_EXT_FAULT_STATUS_ADDR,
> + BIT(channel));
Does this return stale data when the device is in Standby mode?
When the device is in Standby mode (!priv->run_state), automatic measurements
are stopped, and the driver triggers a manual one-shot conversion before
reading attributes:
if (!priv->run_state) {
switch (type) {
case hwmon_temp:
switch (attr) {
case hwmon_temp_input:
case hwmon_temp_max_alarm:
case hwmon_temp_min_alarm:
case hwmon_temp_crit_alarm:
ret = regmap_write(priv->regmap, MCP9982_ONE_SHOT_ADDR, 1);
...
Since hwmon_temp_fault is not included in this wake-up list, it looks like
reading the fault status bypasses the wake-up logic and returns the cached
hardware state from the last active cycle instead of triggering a new
measurement.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260422-add-external-diode-fault-read-v1-1-bb28e03a0766@microchip.com?part=1
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-04-22 8:43 [PATCH] hwmon: mcp9982: Add external diode fault read Victor Duicu
2026-04-22 11:38 ` Guenter Roeck
2026-04-22 12:10 ` sashiko-bot
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