Re: [PATCH v3 4/4] hwmon: (aquacomputer_d5next) Add AMPINEL support

Hi Guenter,

Thanks for the review. I will add the trailing comma and separate the shared report validation and handling of an unknown firmware-version offset from the AMPINEL addition. I also noted the -ENODATA and conversion/scaling wording corrections on patch 2.

If the match function _is_ needed, the reason needs to be explained, even
more so since this may impact USB_PRODUCT_ID_AQUAERO.

The requirement is to keep AMPINEL's keyboard interface bound to hid-generic while the hwmon driver handles telemetry. Both interfaces share the same VID/PID and match aqc_table. With the existing __check_hid_generic(), that ID match is enough for hid-generic to decline the keyboard. Returning -ENODEV from aqc_probe(), or rejecting it in aqc_match() alone, does not make it eligible for hid-generic.

The Aquaero collection check rejects its non-telemetry interfaces during probe, but that check alone does not establish keyboard fallback to hid-generic. V3 leaves Aquaero's collection filtering in probe: aqc_match() accepts it subject to the same generic-driver override checks the core already applies when there is no match callback. I do not have Aquaero hardware and have not validated its keyboard behavior.

The matcher test demonstrates the AMPINEL rejection with the original hid-generic logic and passes with patch 1. This is a userspace harness, not a live kernel fallback test. With both revised modules loaded on the physical AMPINEL, the keyboard registration/capabilities survived hwmon reload and suspend/resume, and its capabilities were preserved on reboot. I will make the matching rationale explicit in the next revision.

FWIW, the raw even can happen prior to this, which will result
in bad data. This also affetcs other devices supported by this
driver (and those with fans can crash when it happens).

Could you clarify the path that permits raw_event during probe here? I checked the series base, 46fde107b4e881f179bf02bca69d8a0020561b3c. include/linux/hid.h documents that callbacks are blocked during probe unless the driver calls hid_device_io_start(). In hid-core.c, hid_device_probe() holds driver_input_lock around the driver's probe, and __hid_input_report() returns -EBUSY when it cannot acquire that lock.

aqc_probe() does not call hid_device_io_start(), and neither hid_hw_start() nor hid_hw_open() releases that lock. My reading is that normal USB reports cannot reach aqc_raw_event() until initialization has completed. Is there another path that bypasses this protection? I have not reproduced the race, and would like to understand it before adding a shared initialization fix.

Thanks,
Vas



On Tuesday, September 15th, 2026 at 7:30 AM, Guenter Roeck [off-list ref] wrote:

On 9/14/26 16:37, Vas Zayarskiy wrote:

quoted

Add read-only total power, total current, input voltage, hotspot
temperature and six channel currents for the Aquacomputer AMPINEL.

Decode its 544-byte input report through the existing serial-number,
temperature and update path, with power, current and voltage handled in
the device-specific switch. Store all readings in hwmon units.

Match only the USB telemetry interface, leaving the separate keyboard
interface to hid-generic. Validate the telemetry collection and report
size before opening the device. Channel labels follow report order;
configuration and alarms are not supported.

Assisted-by: LLM sparse
Signed-off-by: Vas Zayarskiy <redacted>
---
  Documentation/hwmon/aquacomputer_d5next.rst |  11 ++
  drivers/hwmon/Kconfig                       |   4 +-
  drivers/hwmon/aquacomputer_d5next.c         | 107 +++++++++++++++++++-
  3 files changed, 116 insertions(+), 6 deletions(-)

diff --git a/Documentation/hwmon/aquacomputer_d5next.rst b/Documentation/hwmon/aquacomputer_d5next.rst
index 49163f387..faf1c51c1 100644
--- a/Documentation/hwmon/aquacomputer_d5next.rst
+++ b/Documentation/hwmon/aquacomputer_d5next.rst

@@ -13,6 +13,7 @@ Supported devices:
  * Aquacomputer Quadro fan controller
  * Aquacomputer High Flow Next sensor
  * Aquacomputer Leakshield leak prevention system
+* Aquacomputer AMPINEL power monitor
  * Aquacomputer Aquastream XT watercooling pump
  * Aquacomputer Aquastream Ultimate watercooling pump
  * Aquacomputer Poweradjust 3 fan controller

@@ -69,6 +70,16 @@ The Aquastream XT pump exposes temperature readings for the coolant, external se
  and fan IC. It also exposes pump and fan speeds (in RPM), voltages, as well as pump
  current.

+The AMPINEL exposes total power, total current, input voltage, hotspot
+temperature and six channel currents. Channel numbers follow report order;
+their mapping to physical connector pins has not been verified. The readings
+are received approximately twice per second. Only sensor reads are supported;
+the driver does not configure protection settings or report alarms.
+
+For AMPINEL, ``power1_input`` is total power, ``in0_input`` is input voltage,
+``temp1_input`` is hotspot temperature, ``curr1_input`` is total current, and
+``curr[2-7]_input`` are the six channel currents.
+
  The Aquastream Ultimate pump exposes coolant temp and an external temp sensor, along
  with speed, power, voltage and current of both the pump and optionally connected fan.
  It also exposes pressure and flow speed readings.

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 3d8b2c958..06cb246ff 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig

@@ -257,14 +257,14 @@ config SENSORS_AHT10
  	  will be called aht10.

  config SENSORS_AQUACOMPUTER_D5NEXT
-	tristate "Aquacomputer D5 Next, Octo, Quadro, Farbwerk, Farbwerk 360, High Flow Next"
+	tristate "Aquacomputer D5 Next and other USB devices"
  	depends on USB_HID
  	select CRC16
  	help
  	  If you say yes here you get support for sensors and fans of
  	  the Aquacomputer D5 Next watercooling pump, Octo and Quadro fan
  	  controllers, Farbwerk and Farbwerk 360 RGB controllers, High Flow
-	  Next sensor, where available.
+	  Next sensor and AMPINEL power monitor, where available.

  	  This driver can also be built as a module. If so, the module
  	  will be called aquacomputer_d5next.

diff --git a/drivers/hwmon/aquacomputer_d5next.c b/drivers/hwmon/aquacomputer_d5next.c
index b58f5b5c9..e661c4dfa 100644
--- a/drivers/hwmon/aquacomputer_d5next.c
+++ b/drivers/hwmon/aquacomputer_d5next.c

@@ -2,7 +2,7 @@
  /*
   * hwmon driver for Aquacomputer devices (D5 Next, Farbwerk, Farbwerk 360, Octo,
   * Quadro, High Flow Next, Aquaero, Aquastream Ultimate, Leakshield,
- * High Flow USB/MPS Flow family)
+ * High Flow USB/MPS Flow family, AMPINEL)
   *
   * Aquacomputer devices send HID reports (with ID 0x01) every second to report
   * sensor values, except for devices that communicate through the

@@ -23,6 +23,7 @@
  #include <linux/module.h>
  #include <linux/seq_file.h>
  #include <linux/unaligned.h>
+#include <linux/usb.h>

  #define USB_VENDOR_ID_AQUACOMPUTER	0x0c70
  #define USB_PRODUCT_ID_AQUAERO		0xf001

@@ -33,6 +34,7 @@
  #define USB_PRODUCT_ID_OCTO		0xf011
  #define USB_PRODUCT_ID_HIGHFLOWNEXT	0xf012
  #define USB_PRODUCT_ID_LEAKSHIELD	0xf014
+#define USB_PRODUCT_ID_AMPINEL		0xf015
  #define USB_PRODUCT_ID_AQUASTREAMXT	0xf0b6
  #define USB_PRODUCT_ID_AQUASTREAMULT	0xf00b
  #define USB_PRODUCT_ID_POWERADJUST3	0xf0bd

@@ -41,7 +43,7 @@
  enum kinds {
  	d5next, farbwerk, farbwerk360, octo, quadro,
  	highflownext, aquaero, poweradjust3, aquastreamult,
-	aquastreamxt, leakshield, highflow
+	aquastreamxt, leakshield, highflow, ampinel
  };

  static const char *const aqc_device_names[] = {

@@ -56,7 +58,8 @@ static const char *const aqc_device_names[] = {
  	[aquaero] = "aquaero",
  	[aquastreamult] = "aquastreamultimate",
  	[poweradjust3] = "poweradjust3",
-	[highflow] = "highflow" /* Covers MPS Flow devices */
+	[highflow] = "highflow", /* Covers MPS Flow devices */
+	[ampinel] = "ampinel"

Add "," at the end to avoid having to change it whenever a new device is added.

quoted

  };

  #define DRIVER_NAME			"aquacomputer_d5next"

@@ -111,6 +114,16 @@ static u8 aquaero_secondary_ctrl_report[] = {
  #define AQC_FAN_POWER_OFFSET		0x06
  #define AQC_FAN_SPEED_OFFSET		0x08

+/* AMPINEL offsets include the report ID byte. */
+#define AMPINEL_DATA_INTERFACE		1
+#define AMPINEL_STATUS_REPORT_SIZE	544
+#define AMPINEL_NUM_CHANNELS		6
+#define AMPINEL_CHANNEL_CURRENT_START	0x6f
+#define AMPINEL_POWER			0xc7
+#define AMPINEL_CURRENT			0xc9
+#define AMPINEL_VOLTAGE			0xcf
+#define AMPINEL_HOTSPOT			0xe1
+
  /* Specs of the Aquaero fan controllers */
  #define AQUAERO_SERIAL_START			0x07
  #define AQUAERO_FIRMWARE_VERSION		0x0B

@@ -516,6 +529,24 @@ static const char *const label_highflow_speeds[] = {
  	"Flow speed [dL/h]"
  };

+static const char *const label_ampinel_temp[] = {
+	"Hotspot"
+};
+
+static const char *const label_ampinel_power[] = {
+	"Total power"
+};
+
+static const char *const label_ampinel_voltage[] = {
+	"VCC In"
+};
+
+static const char *const label_ampinel_current[] = {
+	"Total current",
+	"Channel 1", "Channel 2", "Channel 3",
+	"Channel 4", "Channel 5", "Channel 6"
+};
+
  struct aqc_fan_structure_offsets {
  	u8 voltage;
  	u8 curr;

@@ -869,6 +900,10 @@ static umode_t aqc_is_visible(const void *data, enum hwmon_sensor_types type, u3
  		break;
  	case hwmon_power:
  		switch (priv->kind) {
+		case ampinel:
+			if (channel == 0)
+				return 0444;
+			break;
  		case aquastreamult:
  			/* Special case to support pump and fan power */
  			if (channel < 2)

@@ -889,6 +924,10 @@ static umode_t aqc_is_visible(const void *data, enum hwmon_sensor_types type, u3
  		break;
  	case hwmon_curr:
  		switch (priv->kind) {
+		case ampinel:
+			if (channel < AMPINEL_NUM_CHANNELS + 1)
+				return 0444;
+			break;
  		case aquastreamult:
  			/* Special case to support pump and fan current */
  			if (channel < 2)

@@ -907,6 +946,10 @@ static umode_t aqc_is_visible(const void *data, enum hwmon_sensor_types type, u3
  		break;
  	case hwmon_in:
  		switch (priv->kind) {
+		case ampinel:
+			if (channel == 0)
+				return 0444;
+			break;
  		case d5next:
  			/* Special case to support +5V and +12V voltage sensors */
  			if (channel < priv->num_fans + 2)

@@ -1336,12 +1379,17 @@ static int aqc_raw_event(struct hid_device *hdev, struct hid_report *report, u8
  		return 0;

  	priv = hid_get_drvdata(hdev);
+	if (priv->kind == ampinel &&
+	    (report->type != HID_INPUT_REPORT || size != AMPINEL_STATUS_REPORT_SIZE ||
+	     data[0] != STATUS_REPORT_ID))
+		return 0;

This is again a bug fix affecting other controllers as well (report size and
input type check).

quoted

  	/* Info provided with every report */
  	priv->serial_number[0] = get_unaligned_be16(data + priv->serial_number_start_offset);
  	priv->serial_number[1] = get_unaligned_be16(data + priv->serial_number_start_offset +
  						    SERIAL_PART_OFFSET);
-	priv->firmware_version = get_unaligned_be16(data + priv->firmware_version_offset);
+	if (priv->firmware_version_offset)
+		priv->firmware_version = get_unaligned_be16(data + priv->firmware_version_offset);

Unrelated to adding support for ampinel.

quoted

  	/* Physical temperature sensor readings */
  	for (i = 0; i < priv->num_temp_sensors; i++) {

@@ -1394,6 +1442,17 @@ static int aqc_raw_event(struct hid_device *hdev, struct hid_report *report, u8

  	/* Special-case sensor readings */
  	switch (priv->kind) {
+	case ampinel:
+		priv->power_input[0] =
+			min_t(u64, get_unaligned_be16(data + AMPINEL_POWER) * 100000ULL,
+			      LONG_MAX);
+		priv->current_input[0] = get_unaligned_be16(data + AMPINEL_CURRENT) * 10;
+		for (i = 0; i < AMPINEL_NUM_CHANNELS; i++)
+			priv->current_input[i + 1] =
+				get_unaligned_be16(data + AMPINEL_CHANNEL_CURRENT_START +
+						   i * AQC_SENSOR_SIZE);
+		priv->voltage_input[0] = get_unaligned_be16(data + AMPINEL_VOLTAGE);
+		break;
  	case aquaero:
  		/* Read calculated virtual temp sensors */
  		i = priv->num_temp_sensors + priv->num_virtual_temp_sensors;

@@ -1519,8 +1578,26 @@ static void aqc_debugfs_init(struct aqc_data *priv)
  		debugfs_create_file("power_cycles", 0444, priv->debugfs, priv, &power_cycles_fops);
  }

+static bool aqc_match(struct hid_device *hdev, bool ignore_special_driver)
+{
+	struct usb_interface *intf;
+
+	if (ignore_special_driver || hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER)
+		return false;
+
+	if (hdev->product != USB_PRODUCT_ID_AMPINEL)
+		return true;
+
+	if (!hid_is_usb(hdev))
+		return false;
+
+	intf = to_usb_interface(hdev->dev.parent);
+	return intf->cur_altsetting->desc.bInterfaceNumber == AMPINEL_DATA_INTERFACE;
+}
+
  static int aqc_probe(struct hid_device *hdev, const struct hid_device_id *id)
  {
+	struct hid_report *report;
  	struct aqc_data *priv;
  	int ret;

@@ -1537,6 +1614,14 @@ static int aqc_probe(struct hid_device *hdev, const struct hid_device_id *id)
  	if (ret)
  		return ret;

+	if (hdev->product == USB_PRODUCT_ID_AMPINEL) {
+		report = hdev->report_enum[HID_INPUT_REPORT].report_id_hash[STATUS_REPORT_ID];
+		if (hdev->maxcollection != 1 ||
+		    hdev->collection[0].usage != (HID_UP_MSVENDOR | 1) ||
+		    !report || report->size != (AMPINEL_STATUS_REPORT_SIZE - 1) * 8)
+			return -ENODEV;
+	}

USB_PRODUCT_ID_AQUAERO has the same or a similar problem and handles it
in the switch statement below. I do not see a reason to handle this one
differently (including the need for the match function which doesn't seem
to be needed for USB_PRODUCT_ID_AQUAERO).

If the match function _is_ needed, the reason needs to be explained, even
more so since this may impact USB_PRODUCT_ID_AQUAERO.

quoted

+
  	ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
  	if (ret)
  		return ret;

@@ -1546,6 +1631,15 @@ static int aqc_probe(struct hid_device *hdev, const struct hid_device_id *id)
  		goto fail_and_stop;

  	switch (hdev->product) {
+	case USB_PRODUCT_ID_AMPINEL:
+		priv->kind = ampinel;
+		priv->num_temp_sensors = 1;
+		priv->temp_sensor_start_offset = AMPINEL_HOTSPOT;

FWIW, the raw even can happen prior to this, which will result
in bad data. This also affetcs other devices supported by this
driver (and those with fans can crash when it happens).

quoted

+		priv->temp_label = label_ampinel_temp;
+		priv->power_label = label_ampinel_power;
+		priv->voltage_label = label_ampinel_voltage;
+		priv->current_label = label_ampinel_current;
+		break;
  	case USB_PRODUCT_ID_AQUAERO:
  		/*
  		 * Aquaero presents itself as three HID devices under the same product ID:

@@ -1795,6 +1889,9 @@ static int aqc_probe(struct hid_device *hdev, const struct hid_device_id *id)
  	}

  	switch (priv->kind) {
+	case ampinel:
+		priv->serial_number_start_offset = AQC_SERIAL_START;
+		break;
  	case aquaero:
  		priv->serial_number_start_offset = AQUAERO_SERIAL_START;
  		priv->firmware_version_offset = AQUAERO_FIRMWARE_VERSION;

@@ -1890,6 +1987,7 @@ static const struct hid_device_id aqc_table[] = {
  	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_QUADRO) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_HIGHFLOWNEXT) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_LEAKSHIELD) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_AMPINEL) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_AQUASTREAMXT) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_AQUASTREAMULT) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_AQUACOMPUTER, USB_PRODUCT_ID_POWERADJUST3) },

@@ -1902,6 +2000,7 @@ MODULE_DEVICE_TABLE(hid, aqc_table);
  static struct hid_driver aqc_driver = {
  	.name = DRIVER_NAME,
  	.id_table = aqc_table,
+	.match = aqc_match,
  	.probe = aqc_probe,
  	.remove = aqc_remove,
  	.raw_event = aqc_raw_event,