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realtek: hwmon: backport lm75 alert polarity patches

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The lm75 alert polarity active-high patch has been accepted upstream.
Replace the downstream version. Additionally add an upstream bugfix
that was identified during the implementation.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/23232
Signed-off-by: Robert Marko <robimarko@gmail.com>
This commit is contained in:
Markus Stockhausen
2026-05-05 20:06:12 +02:00
committed by Robert Marko
parent 8de418547f
commit 4c16b5766c
4 changed files with 104 additions and 59 deletions
Download Patch File Download Diff File Expand all files Collapse all files
target/linux/realtek/dts/rtl9301_d-link_dgs-1250-28x.dts
+1 -1
View File
@@ -79,7 +79,7 @@
compatible = "microchip,tcn75";
reg = <0x48>;
#thermal-sensor-cells = <0>;
alert-polarity-active-high;
ti,alert-polarity-active-high;
};
eeprom@50 {
target/linux/realtek/patches-6.18/028-v7.1-hwmon-lm75-fix-configuration-register-writes.patch
+40
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@@ -0,0 +1,40 @@
From ccef20232ded30ca6e73865458ebe89c0fe48dfe Mon Sep 17 00:00:00 2001
From: Markus Stockhausen <markus.stockhausen@gmx.de>
Date: Sat, 2 May 2026 19:32:07 +0200
Subject: hwmon: (lm75) Fix configuration register writes.
Sensors configurations are defined by set and clear masks. These
do not follow a consistent "clear mask is a superset of set mask"
rule. This relaxed definition breaks lm75_write_config()
static inline int lm75_write_config(struct lm75_data *data, u16 set_mask,
u16 clr_mask)
{
return regmap_update_bits(data->regmap, LM75_REG_CONF,
clr_mask | LM75_SHUTDOWN, set_mask);
}
Basically all bits from set_mask that are not defined in clr_mask are
dropped. Fix that by enhancing the helper to always combine clr_mask
and set_mask into the mask bits of regmap_update_bits().
Fixes: 6da24a25f766 ("hwmon: (lm75) Hide register size differences in regmap access functions")
Suggested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://lore.kernel.org/r/20260502173207.3567876-3-markus.stockhausen@gmx.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
drivers/hwmon/lm75.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -352,7 +352,7 @@ static inline int lm75_write_config(stru
u16 clr_mask)
{
return regmap_update_bits(data->regmap, LM75_REG_CONF,
- clr_mask | LM75_SHUTDOWN, set_mask);
+ clr_mask | set_mask | LM75_SHUTDOWN, set_mask);
}
static irqreturn_t lm75_alarm_handler(int irq, void *private)
target/linux/realtek/patches-6.18/029-v7.2-hwmon-lm75-support-active-high-alert-polarity.patch
+63
View File
@@ -0,0 +1,63 @@
From da96d42a568b98508729abf5c8f05d6e7770443d Mon Sep 17 00:00:00 2001
From: Markus Stockhausen <markus.stockhausen@gmx.de>
Date: Mon, 4 May 2026 17:10:20 +0200
Subject: hwmon: (lm75) Support active-high alert polarity
LM75 devices supported by this driver support configurable active-high
alert polarity. This is already documented in the devicetree description.
Add support for it to the driver.
Follow documentation and defensively enforce active-low if property is
not set. This avoids possible inconsistencies for future devices with
wrong parametrization. No API breakage as all current devices have
their parameters set to active-low.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://lore.kernel.org/r/20260504151020.462342-3-markus.stockhausen@gmx.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
drivers/hwmon/lm75.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -122,7 +122,9 @@ struct lm75_data {
static const u8 lm75_sample_set_masks[] = { 0 << 5, 1 << 5, 2 << 5, 3 << 5 };
-#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
+#define LM75_ALERT_POLARITY_HIGH_8_BIT (BIT(2))
+#define LM75_ALERT_POLARITY_HIGH_16_BIT (BIT(2) << 8)
+#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
/* The structure below stores the configuration values of the supported devices.
* In case of being supported multiple configurations, the default one must
@@ -710,6 +712,7 @@ static void lm75_remove(void *data)
static int lm75_generic_probe(struct device *dev, const char *name,
enum lm75_type kind, int irq, struct regmap *regmap)
{
+ u16 clr_mask, pol_mask, set_mask;
struct device *hwmon_dev;
struct lm75_data *data;
int status, err;
@@ -744,8 +747,18 @@ static int lm75_generic_probe(struct dev
return err;
data->orig_conf = status;
- err = lm75_write_config(data, data->params->set_mask,
- data->params->clr_mask);
+ /* Enforce polarity active-low (default) or active-high (devicetree) */
+ if (!data->params->config_reg_16bits)
+ pol_mask = LM75_ALERT_POLARITY_HIGH_8_BIT;
+ else
+ pol_mask = LM75_ALERT_POLARITY_HIGH_16_BIT;
+
+ clr_mask = data->params->clr_mask | pol_mask;
+ set_mask = data->params->set_mask & ~pol_mask;
+ if (device_property_read_bool(dev, "ti,alert-polarity-active-high"))
+ set_mask |= pol_mask;
+
+ err = lm75_write_config(data, set_mask, clr_mask);
if (err)
return err;
target/linux/realtek/patches-6.18/810-lm75-alert-polarity-swap.patch
-58
View File
@@ -1,58 +0,0 @@
From 92ea53e058d40ebda7326016494e3c21dc536c53 Mon Sep 17 00:00:00 2001
From: Markus Stockhausen <markus.stockhausen@gmx.de>
Date: Mon, 23 Mar 2026 22:12:01 +0200
Subject: [PATCH] hwmon: lm75 alert polarity swap
The LM75 can steer the alert polarity. In default mode the alert
output pin is active-low. This can not be configured with the
existing LM75 driver.
There are hardware designs that use this alert output for an automatic
fan speed control. E.g. the D-Link DGS-1250. This works as follows
- temperature below Tmax threshold -> alert pin low -> fan slow speed
- temperature above Tmax threshold -> alert pin high -> fan high speed
As one can see the hardware design requires the alert pin to be
configured in mode active-high to work as described. Add a LM75 DTS
property "alert-polarity-active-high" that allows to swap the alert
pin behaviour during initialization to active-high.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -122,7 +122,8 @@ struct lm75_data {
static const u8 lm75_sample_set_masks[] = { 0 << 5, 1 << 5, 2 << 5, 3 << 5 };
-#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
+#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
+#define LM75_ALERT_POLARITY_HIGH BIT(2)
/* The structure below stores the configuration values of the supported devices.
* In case of being supported multiple configurations, the default one must
@@ -713,6 +714,7 @@ static int lm75_generic_probe(struct dev
struct device *hwmon_dev;
struct lm75_data *data;
int status, err;
+ u16 set_mask;
data = devm_kzalloc(dev, sizeof(struct lm75_data), GFP_KERNEL);
if (!data)
@@ -744,8 +746,13 @@ static int lm75_generic_probe(struct dev
return err;
data->orig_conf = status;
- err = lm75_write_config(data, data->params->set_mask,
- data->params->clr_mask);
+ set_mask = data->params->set_mask;
+ if (of_property_read_bool(dev->of_node, "alert-polarity-active-high")) {
+ pr_info("set lm75 alert to active high\n");
+ set_mask |= LM75_ALERT_POLARITY_HIGH;
+ }
+
+ err = lm75_write_config(data, set_mask, data->params->clr_mask);
if (err)
return err;