Message-ID: <Z5ojmLCO7DhsT6jd@kekkonen.localdomain>
Date: Wed, 29 Jan 2025 12:48:24 +0000
From: "sakari.ailus@...ux.intel.com" <sakari.ailus@...ux.intel.com>
To: Hans de Goede <hdegoede@...hat.com>
Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Mirela Rabulea <mirela.rabulea@....com>, mchehab@...nel.org,
	hverkuil-cisco@...all.nl, robh@...nel.org, krzk+dt@...nel.org,
	bryan.odonoghue@...aro.org, laurentiu.palcu@....com,
	robert.chiras@....com, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, LnxRevLi@....com,
	kieran.bingham@...asonboard.com, dave.stevenson@...pberrypi.com,
	mike.rudenko@...il.com, alain.volmat@...s.st.com,
	devicetree@...r.kernel.org, conor+dt@...nel.org,
	alexander.stein@...tq-group.com, umang.jain@...asonboard.com,
	zhi.mao@...iatek.com, festevam@...x.de, julien.vuillaumier@....com,
	alice.yuan@....com
Subject: Re: [PATCH v2 2/4] media: ox05b1s: Add omnivision OX05B1S raw sensor
 driver

Hi Hans,

On Sat, Jan 25, 2025 at 11:12:16AM +0100, Hans de Goede wrote:
> Hi Laurent,
> 
> On 25-Jan-25 1:14 AM, Laurent Pinchart wrote:
> > Hi Hans,
> > 
> > On Fri, Jan 24, 2025 at 06:17:40PM +0100, Hans de Goede wrote:
> >> On 26-Nov-24 4:50 PM, Mirela Rabulea wrote:
> >>> Add a v4l2 subdevice driver for the Omnivision OX05B1S RGB-IR sensor.
> >>>
> >>> The Omnivision OX05B1S is a 1/2.5-Inch CMOS image sensor with an
> >>> active array size of 2592 x 1944.
> >>>
> >>> The following features are supported for OX05B1S:
> >>> - Manual exposure an gain control support
> >>> - vblank/hblank control support
> >>> - Supported resolution: 2592 x 1944 @ 30fps (SGRBG10)
> >>>
> >>> Signed-off-by: Mirela Rabulea <mirela.rabulea@....com>
> >>
> >> Thank you for your contribution, I noticed in $subject
> >> that the model-nr ends in a "S" and that you describe
> >> this as a RGB-IR sensor.
> >>
> >> I've been working on OV01A1S support myself and one of
> >> the issues is how to communicate the RGB-IR color-filter
> >> to userspace.
> >>
> >> <snip>
> >>
> >> I see here:
> >>
> >>> +static const struct ox05b1s_sizes ox05b1s_supported_codes[] = {
> >>> +	{
> >>> +		.code = MEDIA_BUS_FMT_SGRBG10_1X10,
> >>> +		.sizes = ox05b1s_sgrbg10_sizes,
> >>> +	}, {
> >>> +		/* sentinel */
> >>> +	}
> >>> +};
> >>
> >> That you are using MEDIA_BUS_FMT_SGRBG10_1X10, but that suggests
> >> this sensor is using a plain Bayer color filter which is not correct.
> >>
> >> Here is what I have come up with:
> >>
> >> diff --git a/include/linux/drm_fourcc.h b/include/linux/drm_fourcc.h
> >> index db679877..68ed65c5 100644
> >> --- a/include/linux/drm_fourcc.h
> >> +++ b/include/linux/drm_fourcc.h
> >> @@ -447,6 +447,8 @@ extern "C" {
> >>  #define DRM_FORMAT_SGRBG10	fourcc_code('B', 'A', '1', '0')
> >>  #define DRM_FORMAT_SGBRG10	fourcc_code('G', 'B', '1', '0')
> >>  #define DRM_FORMAT_SBGGR10	fourcc_code('B', 'G', '1', '0')
> >> +/* Mixed 10 bit bayer + ir pixel pattern found on Omnivision ov01a1s */
> >> +#define DRM_FORMAT_SIGIG_GBGR_IGIG_GRGB10 fourcc_code('O', 'V', '1', 'S')
> >>  
> >>  /* 12-bit Bayer formats */
> >>  #define DRM_FORMAT_SRGGB12	fourcc_code('R', 'G', '1', '2')
> >> diff --git a/include/linux/media-bus-format.h b/include/linux/media-bus-format.h
> >> index b6acf8c8..e2938f0d 100644
> >> --- a/include/linux/media-bus-format.h
> >> +++ b/include/linux/media-bus-format.h
> >> @@ -122,7 +122,7 @@
> >>  #define MEDIA_BUS_FMT_YUV16_1X48		0x202a
> >>  #define MEDIA_BUS_FMT_UYYVYY16_0_5X48		0x202b
> >>  
> >> -/* Bayer - next is	0x3025 */
> >> +/* Bayer - next is	0x3026 */
> >>  #define MEDIA_BUS_FMT_SBGGR8_1X8		0x3001
> >>  #define MEDIA_BUS_FMT_SGBRG8_1X8		0x3013
> >>  #define MEDIA_BUS_FMT_SGRBG8_1X8		0x3002
> >> @@ -159,6 +159,8 @@
> >>  #define MEDIA_BUS_FMT_SGBRG20_1X20		0x3022
> >>  #define MEDIA_BUS_FMT_SGRBG20_1X20		0x3023
> >>  #define MEDIA_BUS_FMT_SRGGB20_1X20		0x3024
> >> +/* Mixed bayer + ir pixel pattern found on ov01a1s */
> >> +#define MEDIA_BUS_FMT_SIGIG_GBGR_IGIG_GRGB10_1X10 0x3025
> >>  
> >>  /* JPEG compressed formats - next is	0x4002 */
> >>  #define MEDIA_BUS_FMT_JPEG_1X8			0x4001
> >> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> >> index 3829c0b6..1b91ed0e 100644
> >> --- a/include/linux/videodev2.h
> >> +++ b/include/linux/videodev2.h
> >> @@ -706,6 +706,9 @@ struct v4l2_pix_format {
> >>  #define V4L2_PIX_FMT_SGBRG16 v4l2_fourcc('G', 'B', '1', '6') /* 16  GBGB.. RGRG.. */
> >>  #define V4L2_PIX_FMT_SGRBG16 v4l2_fourcc('G', 'R', '1', '6') /* 16  GRGR.. BGBG.. */
> >>  #define V4L2_PIX_FMT_SRGGB16 v4l2_fourcc('R', 'G', '1', '6') /* 16  RGRG.. GBGB.. */
> >> +	/* 10bit mixed bayer + ir pixel pattern found on ov01a1s */
> >> +#define V4L2_PIX_FMT_SIGIG_GBGR_IGIG_GRGB10  v4l2_fourcc('O', 'V', '1', 'S') /* unpacked */
> >> +#define V4L2_PIX_FMT_SIGIG_GBGR_IGIG_GRGB10P v4l2_fourcc('O', 'V', '1', 'P') /* packed */
> >>  
> >>  /* HSV formats */
> >>  #define V4L2_PIX_FMT_HSV24 v4l2_fourcc('H', 'S', 'V', '3')
> >>
> >> For this, note:
> >>
> >> 1. This is against libcamera's copy of the relevant linux headers, the paths
> >> to the .h files are different in the kernel
> >>
> >> 2. Since I wrote this I learned that it looks like the intel driver for
> >> the ov01a1s:
> >>
> >> https://github.com/intel/ipu6-drivers/blob/master/drivers/media/i2c/ov01a1s.c
> >>
> >> may have enabled horizontal-flip / mirroring by default, which means that
> >> the order of each of the quads needs to be flipped.
> >>
> >> IMHO we need to resolve how to communicate the color-filters used on
> >> these OV xxxxx"S" models to userspace. When I last discussed this with
> >> Laurent, Laurent suggested using V4L2_PIX_FMT_Y10, combined with
> >> a new field or v4l2-control to query the actual filter.
> > 
> > Yes, adding new pixel formats and media bus codes to represent CFA
> > patterns won't scale. We need to switch to using controls to report
> > those. Sakari is already working on a series for that.
> 
> Interesting, do you have a link to Sakari's work ?

I'm about to post v5 soonish, I'll cc you.

The current patches are two top-most here (metadata-raw branch)
<URL:https://git.retiisi.eu/?p=~sailus/linux.git;a=commitdiff;h=81aa6e3aad1fdf3b2da4a930a0f4e0520a805edd>.

> 
> >> The idea is to separate the depth/packing info from the filter info,
> >> avoiding the possible combinatioral explosion of needing this special
> >> filter with all possible deths. I gave this a quick try but at least on
> >> the libcamera side there is still a lot of code assuming that both
> >> depth and color-filter-type are communicated through a single fmt
> >> integer. Also it seems that in practice there only is this one new
> >> RGB-IR color filter used on the OV xxxxx"S" models so I think we
> >> need just 1 new V4L2_PIX_FMT_ define (*).
> > 
> > Changes in libcamera are surely needed. There's work to be done, we'll
> > do the work, and we'll solve this problem. Let's focus the effort in
> > that direction.
> 
> Ok, so what does that mean for upstreaming support for omnivision
> OVxxxxS sensors? Clearly advertising MEDIA_BUS_FMT_SGRBG10_1X10 is
> wrong. So I guess that upstreaming this driver needs to wait until
> at least the kernel API side of this is resolved?
> 
> Sensors relying on the new CFA control to communicatethe CFA type
> could use a new (e.g.) MEDIA_BUS_FMT_RAW_1X10 or are we going to re-use
> the monochrome (Y only) media bus fmts, so e.g. this sensor would
> advertise MEDIA_BUS_FMT_Y10_1X10 and then the CFA control would provide
> the actual CFA info ?
> 
> IMHO re-using the monochrome (Y only) media bus fmts seems best
> to avoid needing to have to make a "RAW" copy of all of them.

That's an interesting idea. I'll consider this for the next version of the
sensor API patchset, currently I don't see issues with this approach. The
advantage would be that the receiver drivers don't need to explicitly
support the common CSI-2 raw formats.

> 
> This also matches with what we are already doing for IR only sensors.
> AFAIK MEDIA_BUS_FMT_Y10_1X10 is currently already used for infrared
> sensors, so sticking with that and adding a IR CFA option to
> the CFA control to make clear this really is IR (*) seems to make
> sensor for IR only sensors. At which point extending this to RGB-IR
> sensors seems logical.

-- 
Kind regards,

Sakari Ailus

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