[PATCH] platform/x86: int3472: handle GPIO type 0x08 as a power regulator

[Jakob Berg Jespersen]

On the Microsoft Surface Pro 7+, the rear camera's INT3472 device
(INT3472:01, sensor INT347A / ov8865) enumerates a GPIO of type 0x08
in its _DSM which the driver does not recognise, so it is left
unmapped:

  int3472-discrete INT3472:01: GPIO type 0x08 unknown; the sensor may
  not work

The DSDT shows this pin (0x0100AF08, pin 175, active-high) sitting
alongside a normal type-0x0b power-enable GPIO: it gates a second
sensor power rail. Because the type is unknown the rail is never
enabled, the ov8865's "dvdd" supply resolves to a dummy regulator, and
the sensor never probes.

Map type 0x08 for INT347A to a POWER_ENABLE regulator with con_id
"dvdd", the supply the in-tree ov8865 driver already requests, so no
sensor-driver change is needed. ("dvdd" rather than "avdd" because the
type-0x0b power-enable pin on this INT3472 is already registered as
"avdd".)

Type 0x08 is not in the driver's documented function list and is not
otherwise handled by mainline; based on the sensor's supply set and the
con_id that brings it up, it appears to be the DVDD (digital core
voltage) rail, the counterpart to the existing DOVDD (0x10) type.

Related out-of-tree work approached the same rail by adding a new "pwr1"
supply instead of the sensor's existing "dvdd" (linux-surface PR #1867
for the Surface Pro 9, PR #2201 for the Pro 7+ ov8865); neither was sent
upstream. Mapping to "dvdd" keeps the change contained to int3472.

With this change the SP7+ rear camera probes and streams reliably,
validated by over a month of use.

Link: https://github.com/linux-surface/linux-surface/pull/1867
Link: https://github.com/linux-surface/linux-surface/pull/2201
Cc: Tooraj Taraz <tooraj.taraz@xxxxxxxxx>
Cc: Joseph V. Lavigne <jlavig88@xxxxxxxxx>
Signed-off-by: Jakob Berg Jespersen <dev@xxxxxxx>
---
0x08 is left as a bare literal rather than a named constant here; if
its canonical meaning is known I'm happy to add e.g.
INT3472_GPIO_TYPE_DVDD and/or handle it generically like DOVDD in v2.

This is my first kernel contribution, so please bear with me on any
process mistakes.
---
 drivers/platform/x86/intel/int3472/discrete.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/platform/x86/intel/int3472/discrete.c b/drivers/platform/x86/intel/int3472/discrete.c
index 115bb37577a1..98c7b9bc393f 100644
--- a/drivers/platform/x86/intel/int3472/discrete.c
+++ b/drivers/platform/x86/intel/int3472/discrete.c
@@ -164,6 +164,19 @@ static const struct int3472_gpio_map int3472_gpio_map[] = {
 		.con_id = "dvdd",
 		.enable_time_us = 45 * USEC_PER_MSEC,
 	},
+	{	/*
+		 * Surface Pro 7+ ov8865 (rear camera): type 0x08 is an
+		 * undocumented sensor power rail; left undriven the sensor
+		 * stays in a failed power state. "dvdd" rather than "avdd"
+		 * because this INT3472 also has a type 0x0b (power enable)
+		 * pin already registered as "avdd".
+		 */
+		.hid = "INT347A",
+		.type_from = 0x08,
+		.type_to = INT3472_GPIO_TYPE_POWER_ENABLE,
+		.con_id = "dvdd",
+		.enable_time_us = GPIO_REGULATOR_ENABLE_TIME,
+	},
 };
 
 static void int3472_get_con_id_and_polarity(struct int3472_discrete_device *int3472, u8 *type,

---
base-commit: 2b3a5dabe89e330413af403246b648c1890f368f
change-id: 20260719-sp7plus-int3472-8f014b8de79c

Best regards,
--  
Jakob Berg Jespersen <dev@xxxxxxx>