The JC42 compatible thermal sensor on Kingston KSM32ES8/16ME DIMMs
(using Micron E-Die) is an ST Microelectronics STTS2004 (manufacturer
0x104a, device 0x2201). It does not keep the previously programmed
minimum, maximum and critical temperatures after system suspend and
resume (which is a shutdown / startup cycle for the JC42 temperature
sensor). This results in an alarm on system resume because the hardware
default for these values is 0°C (so any environment temperature greater
than 0°C will trigger the alarm).
Example before system suspend:
jc42-i2c-0-1a
Adapter: SMBus PIIX4 adapter port 0 at 0b00
temp1: +34.8°C (low = +0.0°C)
(high = +85.0°C, hyst = +85.0°C)
(crit = +95.0°C, hyst = +95.0°C)
Example after system resume (without this change):
jc42-i2c-0-1a
Adapter: SMBus PIIX4 adapter port 0 at 0b00
temp1: +34.8°C (low = +0.0°C) ALARM (HIGH, CRIT)
(high = +0.0°C, hyst = +0.0°C)
(crit = +0.0°C, hyst = +0.0°C)
Apply the previously read or previously programmed temperature limits on
system resume. This fixes the alarm due to the hardware defaults of 0°C
because the previously applied limits (from a userspace setting) are
re-applied on system resume.
Fixes: 175c490c9e7f ("hwmon: (jc42) Add support for STTS2004 and AT30TSE004")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
---
This is my first change to jc42. I tried to be defensive with applying
the previous values by only configuring them if they are known valid. I
only have this one set of JC42 compatible sensors but I can adapt the
code here based on your suggestions.
drivers/hwmon/jc42.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/hwmon/jc42.c b/drivers/hwmon/jc42.c
index 30888feaf589..f98b28ff10ad 100644
--- a/drivers/hwmon/jc42.c
+++ b/drivers/hwmon/jc42.c
@@ -558,6 +558,19 @@ static int jc42_resume(struct device *dev)
data->config &= ~JC42_CFG_SHUTDOWN;
i2c_smbus_write_word_swapped(data->client, JC42_REG_CONFIG,
data->config);
+
+ if (data->valid || data->temp[t_min])
+ i2c_smbus_write_word_swapped(data->client, temp_regs[t_min],
+ data->temp[t_min]);
+
+ if (data->valid || data->temp[t_max])
+ i2c_smbus_write_word_swapped(data->client, temp_regs[t_max],
+ data->temp[t_max]);
+
+ if (data->valid || data->temp[t_crit])
+ i2c_smbus_write_word_swapped(data->client, temp_regs[t_crit],
+ data->temp[t_crit]);
+
return 0;
}
--
2.38.1
