linux-kernel - Re: [PATCH v1 1/1] media: ov7251: Remap "reset" to "enable" for OV7251

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Message-ID: <Zy48Fc_nUceCs3PK@smile.fi.intel.com>
Date: Fri, 8 Nov 2024 18:28:05 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v1 1/1] media: ov7251: Remap "reset" to "enable" for
 OV7251

On Fri, Nov 08, 2024 at 04:06:39PM +0000, Sakari Ailus wrote:
> On Fri, Nov 08, 2024 at 04:50:24PM +0200, Andy Shevchenko wrote:
> > The driver of OmniVision OV7251 expects "enable" pin instead of "reset".
> > Remap "reset" to "enable" and update polarity.
> > 
> > In particular, the Linux kernel can't load the camera sensor
> > driver on Microsoft Surface Book without this change:
> > 
> >  ov7251 i2c-INT347E:00: supply vdddo not found, using dummy regulator
> >  ov7251 i2c-INT347E:00: supply vddd not found, using dummy regulator
> >  ov7251 i2c-INT347E:00: supply vdda not found, using dummy regulator
> >  ov7251 i2c-INT347E:00: cannot get enable gpio
> >  ov7251 i2c-INT347E:00: probe with driver ov7251 failed with error -2

...

> Should this be cc'd to stable? I guess it's not exactly a fix in the driver
> but a BIOS bug, but it can be worked around in the driver. :-)

It's everything, but a BIOS bug, it's DT bug and whoever first introduced that
GPIO in the driver. Even in the DT present in kernel the pin was referred as
CAM_RST_N, which is exactly how this patch names it.

OTOH it's a fix to the driver that never worked for ACPI case, so there never
was a regression to fix.

-- 
With Best Regards,
Andy Shevchenko