[libcamera-devel] [PATCH 04/10] ipa: libcamera: add metadata for the ov8858 sensor
Nicholas Roth
nicholas at rothemail.net
Fri Oct 28 00:21:37 CEST 2022
> Nice this matches the CCS defined linear gain model.
> However the sensor allows to select two formats for the analogue gain
> the "real gain" format and "sensor gain" format. The selection is made by
> register 0x3503[2] and it would be nice to validate that the driver
> uses the format that you expect.
I think I understand this better after reading the driver. In the register
value settings, I see:
{0x3502, 0x40}, // exposure L
{0x3503, 0x80}, // gain delay ?, exposure delay 1 frame, real gain
{0x3505, 0x80}, // gain option
The 0 low-nibbl indicates we're using "real gain."
According to the datasheet:
0x3503[2]=0, gain[7:0] is real gain format,
where low 4 bits are fraction bits, for
example, 0x10 is 1x gain, 0x28 is 2.5x gain
This tells me that we need to divide reported gain from the driver by 16 to
get a properly-scaled double-value gain, which these gain constants do.
> While V4L2 doesn't specify a unit for the ``EXPOSURE`` control, libcamera
> requires it to be expressed as a number of image lines. Camera sensor
drivers
> that do not comply with this requirement will need to be adapted or will
produce
> incorrect results.
Looks like the driver multiples inputs x16 to convert to 1/16 line length
before writing to the register...
case V4L2_CID_EXPOSURE:
/* 4 least significant bits of expsoure are fractional part */
ret = ov8858_write_reg(ov8858->client,
OV8858_REG_EXPOSURE,
OV8858_REG_VALUE_24BIT,
ctrl->val << 4);
Let me know if this looks good, and what needs to happen to merge this!
Thanks,
-Nicholas
On Thu, Oct 27, 2022 at 12:25 PM Nicholas Roth <nicholas at rothemail.net>
wrote:
> > please pardon me for being pedantic, but I would:
> > libcamera: Add support for ov8858 sensor
> >
> > instead of:
> > ipa: libcamera: add metadata for the ov8858 sensor
>
> Happy to make the change.
>
> > The sensor doesn't seem to be supported mainline :(...
> > Let's start from the first point: where does this driver lives ? What
> > kernel are you using ?
> I'm using Manjaro's kernel 5.19.8-1-MANJARO-ARM (from uname -r).
>
> It looks like my package manager is picking up the Manjaro kernel from
> https://gitlab.manjaro.org/manjaro-arm/packages/core/linux-pinephonepro/-/blob/5.19-megi/config,
> which sets "CONFIG_VIDEO_OV8858=m" in /config otherwise has no
> 8858-related changes. This ultimately pulls the driver from
> https://github.com/megous/linux/blob/orange-pi-5.19/drivers/media/i2c/ov8858.c
> .
>
> Looks like this has been in and out of Torvalds' peripheral view, e.g.:
> https://lkml.iu.edu/hypermail/linux/kernel/1711.1/06245.html
>
> If you think that it would be valuable to try and mainline this, I'd be
> interested to do so once I can get libcamera working on my hardware, though
> I'll likely need some guidance in the process, since I'll be learning a lot.
>
> > Nice this matches the CCS defined linear gain model.
> > However the sensor allows to select two formats for the analogue gain
> > the "real gain" format and "sensor gain" format. The selection is made by
> > register 0x3503[2] and it would be nice to validate that the driver
> > uses the format that you expect.
> Frankly, I'm not sure what you mean by this, but I'll try to find out from
> the driver above and verify.
>
> > Knowing what driver you're using is relevant, in example, as the
> > OV5688 sensor computes exposure in 1/16 of line length. This is not
> > what libcamera expects, and sensor drivers are expected to express the
> > V4L2_CID_EXPOSURE control in line units.
>
> > From Documentation/sensor_driver_requirements.rst
>
> > While V4L2 doesn't specify a unit for the ``EXPOSURE`` control, libcamera
> > requires it to be expressed as a number of image lines. Camera sensor
> drivers
> > that do not comply with this requirement will need to be adapted or will
> produce
> > incorrect results.
>
> Let me read the driver and get back to you.
>
>
> On Thu, Oct 27, 2022 at 11:41 AM Jacopo Mondi <jacopo at jmondi.org> wrote:
>
>> Hi Nicholas,
>>
>> please pardon me for being pedantic, but I would:
>> libcamera: Add support for ov8858 sensor
>>
>> instead of:
>> ipa: libcamera: add metadata for the ov8858 sensor
>>
>> "metadata" is an overloaded already term and usually refers to the
>> properties associated to a captured frame (the term comes from the
>> Android lingo, but we use it too).
>>
>> On Thu, Oct 27, 2022 at 12:55:09AM -0500, Nicholas Roth via
>> libcamera-devel wrote:
>> > From: Nicholas Roth <nicholas at rothemail.net>
>> >
>> > Currently, libcamera does not have information for the ov8858 sensor
>> > used in the PinePhone Pro, a phone designed to run Linux.
>> >
>> > This commit adds metadata, especially that sensor gain is reported and
>> > set in 1/16 discrete increments.
>> >
>> > For more information, see "5.8 manual exposure compensation/ manual
>> > gain compensation" in [0].
>> >
>> > [0] http://www.ahdsensor.com/uploadfile/202008/55322e75316871.pdf
>>
>> The sensor doesn't seem to be supported mainline :(
>> libcamera has a policy that requires supported components to be
>> upstream or at least on their way to upstream (ie posted to the
>> linux-media mailing list). The policy is there because different
>> downstream driver implementations might behave differently one from
>> the other, making it impossible for libcamera to support the part
>> fully. The policy is a strict requirement for ISPs, I guess we're a
>> bit more elastic when it comes to sensor. Howver knowing what driver
>> you are using, where it lives, and if there's any plan to upstream it
>> would be great.
>>
>> Let's start from the first point: where does this driver lives ? What
>> kernel are you using ?
>>
>> Knowing what driver you're using is relevant, in example, as the
>> OV5688 sensor computes exposure in 1/16 of line length. This is not
>> what libcamera expects, and sensor drivers are expected to express the
>> V4L2_CID_EXPOSURE control in line units.
>>
>> From Documentation/sensor_driver_requirements.rst
>>
>> While V4L2 doesn't specify a unit for the ``EXPOSURE`` control, libcamera
>> requires it to be expressed as a number of image lines. Camera sensor
>> drivers
>> that do not comply with this requirement will need to be adapted or will
>> produce
>> incorrect results.
>>
>> >
>> > Signed-off-by: Nicholas Roth <nicholas at rothemail.net>
>> > ---
>> > src/ipa/libipa/camera_sensor_helper.cpp | 11 +++++++++++
>> > src/libcamera/camera_sensor_properties.cpp | 14 ++++++++++++++
>> > 2 files changed, 25 insertions(+)
>> >
>> > diff --git a/src/ipa/libipa/camera_sensor_helper.cpp
>> b/src/ipa/libipa/camera_sensor_helper.cpp
>> > index 35056bec..f2040cbd 100644
>> > --- a/src/ipa/libipa/camera_sensor_helper.cpp
>> > +++ b/src/ipa/libipa/camera_sensor_helper.cpp
>> > @@ -476,6 +476,17 @@ public:
>> > };
>> > REGISTER_CAMERA_SENSOR_HELPER("ov5693", CameraSensorHelperOv5693)
>> >
>> > +class CameraSensorHelperOv8858 : public CameraSensorHelper
>> > +{
>> > +public:
>> > + CameraSensorHelperOv8858()
>> > + {
>> > + gainType_ = AnalogueGainLinear;
>> > + gainConstants_.linear = { 1, 0, 0, 16 };
>> > + }
>> > +};
>>
>> Nice this matches the CCS defined linear gain model.
>> However the sensor allows to select two formats for the analogue gain
>> the "real gain" format and "sensor gain" format. The selection is made by
>> register 0x3503[2] and it would be nice to validate that the driver
>> uses the format that you expect.
>>
>> > +REGISTER_CAMERA_SENSOR_HELPER("m00_f_ov8858", CameraSensorHelperOv8858)
>>
>> Ah! that's a weird name for the sensor entity :)
>>
>> > +
>> > class CameraSensorHelperOv8865 : public CameraSensorHelper
>> > {
>> > public:
>> > diff --git a/src/libcamera/camera_sensor_properties.cpp
>> b/src/libcamera/camera_sensor_properties.cpp
>> > index e5f27f06..d0757c15 100644
>> > --- a/src/libcamera/camera_sensor_properties.cpp
>> > +++ b/src/libcamera/camera_sensor_properties.cpp
>> > @@ -146,6 +146,20 @@ const CameraSensorProperties
>> *CameraSensorProperties::get(const std::string &sen
>> > */
>> > },
>> > } },
>> > + { "m00_f_ov8858", {
>> > + .unitCellSize = { 1200, 1200 },
>>
>> I read 1.12 um x 1.12 um
>>
>> > + .testPatternModes = {
>> > + { controls::draft::TestPatternModeOff, 0
>> },
>> > + {
>> controls::draft::TestPatternModeColorBars, 1 },
>> > + /*
>> > + * No best corresponding test pattern for:
>> > + * 1: "Vertical Color Bar Type 1",
>> > + * 2: "Vertical Color Bar Type 2",
>> > + * 3: "Vertical Color Bar Type 3",
>> > + * 4: "Vertical Color Bar Type 4"
>> > + */
>> > + },
>> > + } },
>> > { "ov8865", {
>> > .unitCellSize = { 1400, 1400 },
>> > .testPatternModes = {
>> > --
>> > 2.34.1
>> >
>>
>
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