linux-kernel - Re: [PATCH 02/13] media: i2c: ov5647: Correct pixel array offset

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Message-ID: <CAPY8ntCVQh-oQyU7Q5AcLrD=1M8kq=S=JFde4d3krtM64DhMJg@mail.gmail.com>
Date: Thu, 6 Nov 2025 12:09:28 +0000
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Jacopo Mondi <jacopo.mondi@...asonboard.com>
Cc: Jai Luthra <jai.luthra@...asonboard.com>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, Jacopo Mondi <jacopo@...ndi.org>, 
	Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, 
	Kieran Bingham <kieran.bingham@...asonboard.com>, 
	David Plowman <david.plowman@...pberrypi.com>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, Peter Robinson <pbrobinson@...il.com>, 
	Stefan Wahren <wahrenst@....net>, "Ivan T. Ivanov" <iivanov@...e.de>
Subject: Re: [PATCH 02/13] media: i2c: ov5647: Correct pixel array offset

Hi Jacopo

On Sun, 2 Nov 2025 at 10:29, Jacopo Mondi <jacopo.mondi@...asonboard.com> wrote:
>
> Hi Jai
>
> On Tue, Oct 28, 2025 at 12:57:13PM +0530, Jai Luthra wrote:
> > From: David Plowman <david.plowman@...pberrypi.com>
> >
> > The top offset in the pixel array is actually 6 (see page 3-1 of the
> > OV5647 data sheet).
> >
> > Fixes: 14f70a3232aa ("media: ov5647: Add support for get_selection()")
> > Signed-off-by: David Plowman <david.plowman@...pberrypi.com>
> > Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
>
> The patch is correct and match the datasheet, but I wonder what the
> implications of having a wrong top were..
>
> I see the full 2592x1944 mode declaring 1944 lines but, as the top row
> was set to 16, it means the mode should read 10 lines past the end of
> the sensor's pixel array..

It's not used in computing the register settings, only reported via
get_selection.

A user of the information from get_selection may get confused by
OV5647_PIXEL_ARRAY_TOP + OV5647_PIXEL_ARRAY_HEIGHT being greater than
OV5647_NATIVE_HEIGHT, but you'd still get images.

  Dave

> Anyway, on the patch
> Reviewed-by: Jacopo Mondi <jacopo.mondi@...asonboard.com>
>
> Thanks
>   j
>
> > ---
> >  drivers/media/i2c/ov5647.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
> > index 985a8e81529d2f88cb38ccb8c94f8605026a28a9..4fed655f5a11c38e76d1ccc9ae9155cf945684ab 100644
> > --- a/drivers/media/i2c/ov5647.c
> > +++ b/drivers/media/i2c/ov5647.c
> > @@ -69,7 +69,7 @@
> >  #define OV5647_NATIVE_HEIGHT         1956U
> >
> >  #define OV5647_PIXEL_ARRAY_LEFT              16U
> > -#define OV5647_PIXEL_ARRAY_TOP               16U
> > +#define OV5647_PIXEL_ARRAY_TOP               6U
> >  #define OV5647_PIXEL_ARRAY_WIDTH     2592U
> >  #define OV5647_PIXEL_ARRAY_HEIGHT    1944U
> >
> >
> > --
> > 2.51.0
> >
> >