[RFC] media: thermal I2C cameras metadata

[RFC] media: thermal I2C cameras metadata

[Matt Ranostay]

Hello et all,

So currently working with some thermal sensors that have coefficients
that needs to be passed back to userspace that aren't related to the
pixel data but are required to normalize to remove scan patterns and
temp gradients. Was wondering the best way to do this, and hope it
isn't some is kludge of the close captioning, or just passing raw data
as another column line.

Datasheet: https://www.melexis.com/en/product/MLX90640/Far-Infrared-Thermal-Sensor-Array

Thanks,

Matt

Re: [RFC] media: thermal I2C cameras metadata

[Sakari Ailus]

Hi Matt,

On Sun, Jul 15, 2018 at 11:05:42PM -0700, Matt Ranostay wrote:
> Hello et all,
> 
> So currently working with some thermal sensors that have coefficients
> that needs to be passed back to userspace that aren't related to the
> pixel data but are required to normalize to remove scan patterns and
> temp gradients. Was wondering the best way to do this, and hope it
> isn't some is kludge of the close captioning, or just passing raw data
> as another column line.

Are you referring to the EEPROM content or something else?

For EEPROM, I could think of just exposing the EEPROM to the user space
as-is using the NVMEM API. This information is very, very device specific
and therefore using a generic interface to access individual values there
isn't really useful.

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi

Re: [RFC] media: thermal I2C cameras metadata

[Matt Ranostay]

On Mon, Jul 23, 2018 at 4:35 AM, Sakari Ailus <sakari.ailus@iki.fi> wrote:
> Hi Matt,
>
> On Sun, Jul 15, 2018 at 11:05:42PM -0700, Matt Ranostay wrote:
>> Hello et all,
>>
>> So currently working with some thermal sensors that have coefficients
>> that needs to be passed back to userspace that aren't related to the
>> pixel data but are required to normalize to remove scan patterns and
>> temp gradients. Was wondering the best way to do this, and hope it
>> isn't some is kludge of the close captioning, or just passing raw data
>> as another column line.
>
> Are you referring to the EEPROM content or something else?
>
> For EEPROM, I could think of just exposing the EEPROM to the user space
> as-is using the NVMEM API. This information is very, very device specific
> and therefore using a generic interface to access individual values there
> isn't really useful.
>

Actually that is okay for the EEPROM data that is per sensor, and
nvram does seem like it would work.
But there is per video frame data that is required along with the
static EEPROM data to calculate the actual end result.

- Matt

> --
> Sakari Ailus
> e-mail: sakari.ailus@iki.fi

Re: [RFC] media: thermal I2C cameras metadata

[Sakari Ailus]

On Tue, Jul 24, 2018 at 11:05:47PM -0700, Matt Ranostay wrote:
> On Mon, Jul 23, 2018 at 4:35 AM, Sakari Ailus <sakari.ailus@iki.fi> wrote:
> > Hi Matt,
> >
> > On Sun, Jul 15, 2018 at 11:05:42PM -0700, Matt Ranostay wrote:
> >> Hello et all,
> >>
> >> So currently working with some thermal sensors that have coefficients
> >> that needs to be passed back to userspace that aren't related to the
> >> pixel data but are required to normalize to remove scan patterns and
> >> temp gradients. Was wondering the best way to do this, and hope it
> >> isn't some is kludge of the close captioning, or just passing raw data
> >> as another column line.
> >
> > Are you referring to the EEPROM content or something else?
> >
> > For EEPROM, I could think of just exposing the EEPROM to the user space
> > as-is using the NVMEM API. This information is very, very device specific
> > and therefore using a generic interface to access individual values there
> > isn't really useful.
> >
> 
> Actually that is okay for the EEPROM data that is per sensor, and
> nvram does seem like it would work.
> But there is per video frame data that is required along with the
> static EEPROM data to calculate the actual end result.

Could you point out what that might be on the datasheet?

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi

Re: [RFC] media: thermal I2C cameras metadata

[Matt Ranostay]

On Wed, Jul 25, 2018 at 2:09 AM, Sakari Ailus <sakari.ailus@iki.fi> wrote:
> On Tue, Jul 24, 2018 at 11:05:47PM -0700, Matt Ranostay wrote:
>> On Mon, Jul 23, 2018 at 4:35 AM, Sakari Ailus <sakari.ailus@iki.fi> wrote:
>> > Hi Matt,
>> >
>> > On Sun, Jul 15, 2018 at 11:05:42PM -0700, Matt Ranostay wrote:
>> >> Hello et all,
>> >>
>> >> So currently working with some thermal sensors that have coefficients
>> >> that needs to be passed back to userspace that aren't related to the
>> >> pixel data but are required to normalize to remove scan patterns and
>> >> temp gradients. Was wondering the best way to do this, and hope it
>> >> isn't some is kludge of the close captioning, or just passing raw data
>> >> as another column line.
>> >
>> > Are you referring to the EEPROM content or something else?
>> >
>> > For EEPROM, I could think of just exposing the EEPROM to the user space
>> > as-is using the NVMEM API. This information is very, very device specific
>> > and therefore using a generic interface to access individual values there
>> > isn't really useful.
>> >
>>
>> Actually that is okay for the EEPROM data that is per sensor, and
>> nvram does seem like it would work.
>> But there is per video frame data that is required along with the
>> static EEPROM data to calculate the actual end result.
>
> Could you point out what that might be on the datasheet?

Datasheet: https://www.melexis.com/-/media/files/documents/datasheets/mlx90640-datasheet-melexis.pdf

On page 18 it documents that 0x700-0x73f  are required for the various
userspace calculations along with the other static EEPROM data.

>
> --
> Sakari Ailus
> e-mail: sakari.ailus@iki.fi