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

[Sakari Ailus]

Hi Jakob,

Thanks for the patch.

On Sun, Jul 19, 2026 at 08:15:12PM +0200, Jakob Berg Jespersen wrote:
> 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".
> +		 */

GPIO type 8 is in fact "POWER1" (type 7 being "POWER0"). This hasn't been
seen anywhere yet so support for it hasn't been added either.

I understand the POWER_ENABLE GPIO is for executing the entire power
sequence and isn't expected to be found with the other regulators, hence an
apparent conflict here wouldn't be an issue.

I think for now we could map type POWER1 (8) to "dvdd", however not using a
quirk but doing it for all devices, like mapping POWER_ENABLE to "avdd".
That'd leave mapping POWER0 to "avdd" for later. The GPIO definition for
POWER0 could be added in any case.

I wonder what Hans or Dan think.

> +		.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,
> 

-- 
Kind regards,

Sakari Ailus