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

[Jakob Berg Jespersen]

On Monday, July 20th, 2026 at 12:14, Hans de Goede <hansg@xxxxxxxxxx> wrote:

> Hi,
> 
> On 20-Jul-26 00:00, Sakari Ailus wrote:
> > 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 was wondering what the internal Intel headers said for type 8, so thank
> you for clarifying that that is called POWER1. Adding a generic mapping
> of POWER1 to "dvdd" instead of using a quirk sounds good to me.
> 
> Regards,
> 
> Hans
> 
> 


Thanks both, and thanks for the POWER0/POWER1 naming.

That approach makes sense to me. For v2 I'll:

 * add INT3472_GPIO_TYPE_POWER0 (7) and INT3472_GPIO_TYPE_POWER1 (8)
   definitions,
 * map POWER1 to "dvdd" generically in int3472_get_con_id_and_polarity(),
   dropping the INT347A quirk,
 * leave POWER0 defined but unmapped for now.

I'll retest on the Surface Pro 7+ and send v2, with a Suggested-by:
trailer for you, Sakari, for the generic approach.

Thanks for the quick review.
Jakob