diff mbox series

[v4,2/4] iio:temperature:mlx90632: Adding extended calibration option

Message ID 20200808121026.1300375-3-cmo@melexis.com
State New
Headers show
Series iio: temperature: mlx90632: Add extended calibration calculations | expand

Commit Message

Crt Mori Aug. 8, 2020, 12:10 p.m. UTC
For some time the market wants medical grade accuracy in medical range,
while still retaining the declared accuracy outside of the medical range
within the same sensor. That is why we created extended calibration
which is automatically switched to when object temperature is too high.

This patch also introduces the object_ambient_temperature variable which
is needed for more accurate calculation of the object infra-red
footprint as sensor's ambient temperature might be totally different
than what the ambient temperature is at object and that is why we can
have some more errors which can be eliminated. Currently this temperature
is fixed at 25, but the interface to adjust it by user (with external
sensor or just IR measurement of the other object which acts as ambient),
will be introduced in another commit.

Signed-off-by: Crt Mori <cmo@melexis.com>
---
 drivers/iio/temperature/mlx90632.c | 212 ++++++++++++++++++++++++++++-
 1 file changed, 210 insertions(+), 2 deletions(-)

Comments

Andy Shevchenko Aug. 8, 2020, 8:03 p.m. UTC | #1
On Sat, Aug 8, 2020 at 3:11 PM Crt Mori <cmo@melexis.com> wrote:
>
> For some time the market wants medical grade accuracy in medical range,
> while still retaining the declared accuracy outside of the medical range
> within the same sensor. That is why we created extended calibration
> which is automatically switched to when object temperature is too high.
>
> This patch also introduces the object_ambient_temperature variable which
> is needed for more accurate calculation of the object infra-red
> footprint as sensor's ambient temperature might be totally different
> than what the ambient temperature is at object and that is why we can
> have some more errors which can be eliminated. Currently this temperature
> is fixed at 25, but the interface to adjust it by user (with external
> sensor or just IR measurement of the other object which acts as ambient),
> will be introduced in another commit.

The kernel doc patch should go before this patch.

...

> +       *ambient_new_raw = (s16)read_tmp;

> +       *ambient_old_raw = (s16)read_tmp;

Sorry, did I miss your answer about these castings all over the patch?

...

> +       ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
> +       ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
> +       ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
> +       ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
> +       ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
> +       ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);

What so special about these magic 17, 18, 19? Can you provide definitions?

...

> +       int tries = 4;

> +       while (tries-- > 0) {
> +               ret = mlx90632_perform_measurement(data);
> +               if (ret < 0)
> +                       goto read_unlock;
> +
> +               if (ret == 19)
> +                       break;
> +       }
> +       if (tries < 0) {
> +               ret = -ETIMEDOUT;
> +               goto read_unlock;
> +       }

Please avoid ping-pong type of changes in the same series (similar way
as for kernel doc), which means don't introduce something you are
going to change later on. Patch to move to do {} while () should go
before this one.
Crt Mori Aug. 8, 2020, 9:57 p.m. UTC | #2
Hi,
I am very sorry you missed them, I thought you saw it (reply on v3 of
the patch). Maybe something happened to that mail, as it contained
link to datasheet, so I will omit it now.

Except for the order, only the remarks below are still open (did you
get the polling trail I did?)

On Sat, 8 Aug 2020 at 22:04, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
>
> On Sat, Aug 8, 2020 at 3:11 PM Crt Mori <cmo@melexis.com> wrote:
> >
> > For some time the market wants medical grade accuracy in medical range,
> > while still retaining the declared accuracy outside of the medical range
> > within the same sensor. That is why we created extended calibration
> > which is automatically switched to when object temperature is too high.
> >
> > This patch also introduces the object_ambient_temperature variable which
> > is needed for more accurate calculation of the object infra-red
> > footprint as sensor's ambient temperature might be totally different
> > than what the ambient temperature is at object and that is why we can
> > have some more errors which can be eliminated. Currently this temperature
> > is fixed at 25, but the interface to adjust it by user (with external
> > sensor or just IR measurement of the other object which acts as ambient),
> > will be introduced in another commit.
>
> The kernel doc patch should go before this patch.
>
> ...
>
> > +       *ambient_new_raw = (s16)read_tmp;
>
> > +       *ambient_old_raw = (s16)read_tmp;
>
> Sorry, did I miss your answer about these castings all over the patch?
>

These castings are in fact needed. You read unsigned integer, but the
return value is signed integer. Without the cast it did not extend the
signed bit, but just wrote the value to signed. Also I find it more
obvious with casts, that I did not "accidentally" convert to signed.

> ...
>
> > +       ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
> > +       ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
> > +       ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
> > +       ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
> > +       ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
> > +       ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);
>
> What so special about these magic 17, 18, 19? Can you provide definitions?
>
When we started 0 to 19 were all open for access, from userspace, then
only 1 and 2 were used with calculations, and now we use 17, 18 and
19. Matter of fact is, I can't provide a descriptive name as it
depends on DSP version and as you can see now within the same DSP
version, also on the ID part. While RAM3 vs RAM1 and RAM2 could be
named RAM_OBJECT1, RAM_OBJECT2, RAM_AMBIENT, knowing our development
that might not be true in the next configuration, so I rather keep the
naming as in the datasheet.

> ...
>
> > +       int tries = 4;
>
> > +       while (tries-- > 0) {
> > +               ret = mlx90632_perform_measurement(data);
> > +               if (ret < 0)
> > +                       goto read_unlock;
> > +
> > +               if (ret == 19)
> > +                       break;
> > +       }
> > +       if (tries < 0) {
> > +               ret = -ETIMEDOUT;
> > +               goto read_unlock;
> > +       }
>
> Please avoid ping-pong type of changes in the same series (similar way
> as for kernel doc), which means don't introduce something you are
> going to change later on. Patch to move to do {} while () should go
> before this one.

OK, will fix that ordering in v5, but will wait till we solve also
above discussions to avoid adding new versions.

>
> --
> With Best Regards,
> Andy Shevchenko

And about that voodoo stuff with numbers:

Honestly, the equation is in the datasheet[1] and this is just making
floating point to fixed point with proper intermediate scaling
(initially I had defines of TENTOX, but that was not desired). There
is no better explanation of this voodoo.
Jonathan Cameron Aug. 9, 2020, 1:32 p.m. UTC | #3
On Sat, 8 Aug 2020 23:57:59 +0200
Crt Mori <cmo@melexis.com> wrote:

> Hi,
> I am very sorry you missed them, I thought you saw it (reply on v3 of
> the patch). Maybe something happened to that mail, as it contained
> link to datasheet, so I will omit it now.
> 
> Except for the order, only the remarks below are still open (did you
> get the polling trail I did?)
> 
> On Sat, 8 Aug 2020 at 22:04, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> >
> > On Sat, Aug 8, 2020 at 3:11 PM Crt Mori <cmo@melexis.com> wrote:  
> > >
> > > For some time the market wants medical grade accuracy in medical range,
> > > while still retaining the declared accuracy outside of the medical range
> > > within the same sensor. That is why we created extended calibration
> > > which is automatically switched to when object temperature is too high.
> > >
> > > This patch also introduces the object_ambient_temperature variable which
> > > is needed for more accurate calculation of the object infra-red
> > > footprint as sensor's ambient temperature might be totally different
> > > than what the ambient temperature is at object and that is why we can
> > > have some more errors which can be eliminated. Currently this temperature
> > > is fixed at 25, but the interface to adjust it by user (with external
> > > sensor or just IR measurement of the other object which acts as ambient),
> > > will be introduced in another commit.  
> >
> > The kernel doc patch should go before this patch.
> >
> > ...
> >  
> > > +       *ambient_new_raw = (s16)read_tmp;  
> >  
> > > +       *ambient_old_raw = (s16)read_tmp;  
> >
> > Sorry, did I miss your answer about these castings all over the patch?
> >  
> 
> These castings are in fact needed. You read unsigned integer, but the
> return value is signed integer. Without the cast it did not extend the
> signed bit, but just wrote the value to signed. Also I find it more
> obvious with casts, that I did not "accidentally" convert to signed.

Should we perhaps be making this explicit for the cases where we
are sign extending?  That doesn't include these two as the lvalue
is s16, but does include some of the others.

sign_extend32(read_tmp, 15)

> 
> > ...
> >  
> > > +       ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
> > > +       ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
> > > +       ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
> > > +       ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
> > > +       ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
> > > +       ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);  
> >
> > What so special about these magic 17, 18, 19? Can you provide definitions?
> >  
> When we started 0 to 19 were all open for access, from userspace, then
> only 1 and 2 were used with calculations, and now we use 17, 18 and
> 19. Matter of fact is, I can't provide a descriptive name as it
> depends on DSP version and as you can see now within the same DSP
> version, also on the ID part. While RAM3 vs RAM1 and RAM2 could be
> named RAM_OBJECT1, RAM_OBJECT2, RAM_AMBIENT, knowing our development
> that might not be true in the next configuration, so I rather keep the
> naming as in the datasheet.
Normal solution for that is to version the defines as well.

MLX90632_FW3_RAM_1_AMBIENT etc
When a new version changes this, then you introduced new defines to
support that firmware.

> 
> > ...
> >  
> > > +       int tries = 4;  
> >  
> > > +       while (tries-- > 0) {
> > > +               ret = mlx90632_perform_measurement(data);
> > > +               if (ret < 0)
> > > +                       goto read_unlock;
> > > +
> > > +               if (ret == 19)
> > > +                       break;
> > > +       }
> > > +       if (tries < 0) {
> > > +               ret = -ETIMEDOUT;
> > > +               goto read_unlock;
> > > +       }  
> >
> > Please avoid ping-pong type of changes in the same series (similar way
> > as for kernel doc), which means don't introduce something you are
> > going to change later on. Patch to move to do {} while () should go
> > before this one.  
> 
> OK, will fix that ordering in v5, but will wait till we solve also
> above discussions to avoid adding new versions.
> 
> >
> > --
> > With Best Regards,
> > Andy Shevchenko  
> 
> And about that voodoo stuff with numbers:
> 
> Honestly, the equation is in the datasheet[1] and this is just making
> floating point to fixed point with proper intermediate scaling
> (initially I had defines of TENTOX, but that was not desired). There
> is no better explanation of this voodoo.

We all love fixed point arithmetic :)

Jonathan
Crt Mori Aug. 9, 2020, 9:05 p.m. UTC | #4
On Sun, 9 Aug 2020 at 15:32, Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sat, 8 Aug 2020 23:57:59 +0200
> Crt Mori <cmo@melexis.com> wrote:
>
> > Hi,
> > I am very sorry you missed them, I thought you saw it (reply on v3 of
> > the patch). Maybe something happened to that mail, as it contained
> > link to datasheet, so I will omit it now.
> >
> > Except for the order, only the remarks below are still open (did you
> > get the polling trail I did?)
> >
> > On Sat, 8 Aug 2020 at 22:04, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > >
> > > On Sat, Aug 8, 2020 at 3:11 PM Crt Mori <cmo@melexis.com> wrote:
> > > >
> > > > For some time the market wants medical grade accuracy in medical range,
> > > > while still retaining the declared accuracy outside of the medical range
> > > > within the same sensor. That is why we created extended calibration
> > > > which is automatically switched to when object temperature is too high.
> > > >
> > > > This patch also introduces the object_ambient_temperature variable which
> > > > is needed for more accurate calculation of the object infra-red
> > > > footprint as sensor's ambient temperature might be totally different
> > > > than what the ambient temperature is at object and that is why we can
> > > > have some more errors which can be eliminated. Currently this temperature
> > > > is fixed at 25, but the interface to adjust it by user (with external
> > > > sensor or just IR measurement of the other object which acts as ambient),
> > > > will be introduced in another commit.
> > >
> > > The kernel doc patch should go before this patch.
> > >
> > > ...
> > >
> > > > +       *ambient_new_raw = (s16)read_tmp;
> > >
> > > > +       *ambient_old_raw = (s16)read_tmp;
> > >
> > > Sorry, did I miss your answer about these castings all over the patch?
> > >
> >
> > These castings are in fact needed. You read unsigned integer, but the
> > return value is signed integer. Without the cast it did not extend the
> > signed bit, but just wrote the value to signed. Also I find it more
> > obvious with casts, that I did not "accidentally" convert to signed.
>
> Should we perhaps be making this explicit for the cases where we
> are sign extending?  That doesn't include these two as the lvalue
> is s16, but does include some of the others.
>
> sign_extend32(read_tmp, 15)
>

So for you lines like
s32 read;
read = (read + (s16)read_tmp) / 2;

would actually be better as:
read = (read + sign_extend32(read_tmp, 15)) / 2;

Hm, strange. I would read that more align the read_tmp to 32 bit than
the value you have in read_tmp is actually a signed 16 bit integer...

> >
> > > ...
> > >
> > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
> > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
> > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
> > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
> > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
> > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);
> > >
> > > What so special about these magic 17, 18, 19? Can you provide definitions?
> > >
> > When we started 0 to 19 were all open for access, from userspace, then
> > only 1 and 2 were used with calculations, and now we use 17, 18 and
> > 19. Matter of fact is, I can't provide a descriptive name as it
> > depends on DSP version and as you can see now within the same DSP
> > version, also on the ID part. While RAM3 vs RAM1 and RAM2 could be
> > named RAM_OBJECT1, RAM_OBJECT2, RAM_AMBIENT, knowing our development
> > that might not be true in the next configuration, so I rather keep the
> > naming as in the datasheet.
> Normal solution for that is to version the defines as well.
>
> MLX90632_FW3_RAM_1_AMBIENT etc
> When a new version changes this, then you introduced new defines to
> support that firmware.
>

OK will add those, but it is ending up as:
MLX90632_RAM_DSP5_AMBIENT
MLX90632_RAM_DSP5_EXTENDED_AMBIENT
MLX90632_RAM_DSP5_OBJECT_1
MLX90632_RAM_DSP5_EXTENDED_OBJECT_1
MLX90632_RAM_DSP5_OBJECT_2
MLX90632_RAM_DSP5_EXTENDED_OBJECT_2

ok?
> >
> > > ...
> > >
> > > > +       int tries = 4;
> > >
> > > > +       while (tries-- > 0) {
> > > > +               ret = mlx90632_perform_measurement(data);
> > > > +               if (ret < 0)
> > > > +                       goto read_unlock;
> > > > +
> > > > +               if (ret == 19)
> > > > +                       break;
> > > > +       }
> > > > +       if (tries < 0) {
> > > > +               ret = -ETIMEDOUT;
> > > > +               goto read_unlock;
> > > > +       }
> > >
> > > Please avoid ping-pong type of changes in the same series (similar way
> > > as for kernel doc), which means don't introduce something you are
> > > going to change later on. Patch to move to do {} while () should go
> > > before this one.
> >
> > OK, will fix that ordering in v5, but will wait till we solve also
> > above discussions to avoid adding new versions.
> >
> > >
> > > --
> > > With Best Regards,
> > > Andy Shevchenko
> >
> > And about that voodoo stuff with numbers:
> >
> > Honestly, the equation is in the datasheet[1] and this is just making
> > floating point to fixed point with proper intermediate scaling
> > (initially I had defines of TENTOX, but that was not desired). There
> > is no better explanation of this voodoo.
>
> We all love fixed point arithmetic :)
>
> Jonathan
Crt Mori Aug. 11, 2020, 7:53 a.m. UTC | #5
On Sun, 9 Aug 2020 at 23:05, Crt Mori <cmo@melexis.com> wrote:
>
> On Sun, 9 Aug 2020 at 15:32, Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Sat, 8 Aug 2020 23:57:59 +0200
> > Crt Mori <cmo@melexis.com> wrote:
> >
> > > Hi,
> > > I am very sorry you missed them, I thought you saw it (reply on v3 of
> > > the patch). Maybe something happened to that mail, as it contained
> > > link to datasheet, so I will omit it now.
> > >
> > > Except for the order, only the remarks below are still open (did you
> > > get the polling trail I did?)
> > >
> > > On Sat, 8 Aug 2020 at 22:04, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > > >
> > > > On Sat, Aug 8, 2020 at 3:11 PM Crt Mori <cmo@melexis.com> wrote:
> > > > >
> > > > > For some time the market wants medical grade accuracy in medical range,
> > > > > while still retaining the declared accuracy outside of the medical range
> > > > > within the same sensor. That is why we created extended calibration
> > > > > which is automatically switched to when object temperature is too high.
> > > > >
> > > > > This patch also introduces the object_ambient_temperature variable which
> > > > > is needed for more accurate calculation of the object infra-red
> > > > > footprint as sensor's ambient temperature might be totally different
> > > > > than what the ambient temperature is at object and that is why we can
> > > > > have some more errors which can be eliminated. Currently this temperature
> > > > > is fixed at 25, but the interface to adjust it by user (with external
> > > > > sensor or just IR measurement of the other object which acts as ambient),
> > > > > will be introduced in another commit.
> > > >
> > > > The kernel doc patch should go before this patch.
> > > >
> > > > ...
> > > >
> > > > > +       *ambient_new_raw = (s16)read_tmp;
> > > >
> > > > > +       *ambient_old_raw = (s16)read_tmp;
> > > >
> > > > Sorry, did I miss your answer about these castings all over the patch?
> > > >
> > >
> > > These castings are in fact needed. You read unsigned integer, but the
> > > return value is signed integer. Without the cast it did not extend the
> > > signed bit, but just wrote the value to signed. Also I find it more
> > > obvious with casts, that I did not "accidentally" convert to signed.
> >
> > Should we perhaps be making this explicit for the cases where we
> > are sign extending?  That doesn't include these two as the lvalue
> > is s16, but does include some of the others.
> >
> > sign_extend32(read_tmp, 15)
> >
>
> So for you lines like
> s32 read;
> read = (read + (s16)read_tmp) / 2;
>
> would actually be better as:
> read = (read + sign_extend32(read_tmp, 15)) / 2;
>
> Hm, strange. I would read that more align the read_tmp to 32 bit than
> the value you have in read_tmp is actually a signed 16 bit integer...
>

OK, I did some trails without the casts and had deja-vu from the first
series of patches I submitted.  I noticed that without a cast the
value that ends up in variable is not extended to signed, but it is
unsigned value truncated. This same finding leads to have these casts
already in current ambient and object raw read functions.

So now only debate is if sign_extend32 is useful in this case, as read
in the current case is 32 bit (before it was also 16 bit).

My preference is to leave unified across the driver.

> > >
> > > > ...
> > > >
> > > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
> > > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
> > > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
> > > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
> > > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
> > > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);
> > > >
> > > > What so special about these magic 17, 18, 19? Can you provide definitions?
> > > >
> > > When we started 0 to 19 were all open for access, from userspace, then
> > > only 1 and 2 were used with calculations, and now we use 17, 18 and
> > > 19. Matter of fact is, I can't provide a descriptive name as it
> > > depends on DSP version and as you can see now within the same DSP
> > > version, also on the ID part. While RAM3 vs RAM1 and RAM2 could be
> > > named RAM_OBJECT1, RAM_OBJECT2, RAM_AMBIENT, knowing our development
> > > that might not be true in the next configuration, so I rather keep the
> > > naming as in the datasheet.
> > Normal solution for that is to version the defines as well.
> >
> > MLX90632_FW3_RAM_1_AMBIENT etc
> > When a new version changes this, then you introduced new defines to
> > support that firmware.
> >
>
> OK will add those, but it is ending up as:
> MLX90632_RAM_DSP5_AMBIENT
> MLX90632_RAM_DSP5_EXTENDED_AMBIENT
> MLX90632_RAM_DSP5_OBJECT_1
> MLX90632_RAM_DSP5_EXTENDED_OBJECT_1
> MLX90632_RAM_DSP5_OBJECT_2
> MLX90632_RAM_DSP5_EXTENDED_OBJECT_2
>
> ok?
> > >
> > > > ...
> > > >
> > > > > +       int tries = 4;
> > > >
> > > > > +       while (tries-- > 0) {
> > > > > +               ret = mlx90632_perform_measurement(data);
> > > > > +               if (ret < 0)
> > > > > +                       goto read_unlock;
> > > > > +
> > > > > +               if (ret == 19)
> > > > > +                       break;
> > > > > +       }
> > > > > +       if (tries < 0) {
> > > > > +               ret = -ETIMEDOUT;
> > > > > +               goto read_unlock;
> > > > > +       }
> > > >
> > > > Please avoid ping-pong type of changes in the same series (similar way
> > > > as for kernel doc), which means don't introduce something you are
> > > > going to change later on. Patch to move to do {} while () should go
> > > > before this one.
> > >
> > > OK, will fix that ordering in v5, but will wait till we solve also
> > > above discussions to avoid adding new versions.
> > >
> > > >
> > > > --
> > > > With Best Regards,
> > > > Andy Shevchenko
> > >
> > > And about that voodoo stuff with numbers:
> > >
> > > Honestly, the equation is in the datasheet[1] and this is just making
> > > floating point to fixed point with proper intermediate scaling
> > > (initially I had defines of TENTOX, but that was not desired). There
> > > is no better explanation of this voodoo.
> >
> > We all love fixed point arithmetic :)
> >
> > Jonathan
Jonathan Cameron Aug. 16, 2020, 9:09 a.m. UTC | #6
On Tue, 11 Aug 2020 09:53:55 +0200
Crt Mori <cmo@melexis.com> wrote:

> On Sun, 9 Aug 2020 at 23:05, Crt Mori <cmo@melexis.com> wrote:
> >
> > On Sun, 9 Aug 2020 at 15:32, Jonathan Cameron <jic23@kernel.org> wrote:  
> > >
> > > On Sat, 8 Aug 2020 23:57:59 +0200
> > > Crt Mori <cmo@melexis.com> wrote:
> > >  
> > > > Hi,
> > > > I am very sorry you missed them, I thought you saw it (reply on v3 of
> > > > the patch). Maybe something happened to that mail, as it contained
> > > > link to datasheet, so I will omit it now.
> > > >
> > > > Except for the order, only the remarks below are still open (did you
> > > > get the polling trail I did?)
> > > >
> > > > On Sat, 8 Aug 2020 at 22:04, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:  
> > > > >
> > > > > On Sat, Aug 8, 2020 at 3:11 PM Crt Mori <cmo@melexis.com> wrote:  
> > > > > >
> > > > > > For some time the market wants medical grade accuracy in medical range,
> > > > > > while still retaining the declared accuracy outside of the medical range
> > > > > > within the same sensor. That is why we created extended calibration
> > > > > > which is automatically switched to when object temperature is too high.
> > > > > >
> > > > > > This patch also introduces the object_ambient_temperature variable which
> > > > > > is needed for more accurate calculation of the object infra-red
> > > > > > footprint as sensor's ambient temperature might be totally different
> > > > > > than what the ambient temperature is at object and that is why we can
> > > > > > have some more errors which can be eliminated. Currently this temperature
> > > > > > is fixed at 25, but the interface to adjust it by user (with external
> > > > > > sensor or just IR measurement of the other object which acts as ambient),
> > > > > > will be introduced in another commit.  
> > > > >
> > > > > The kernel doc patch should go before this patch.
> > > > >
> > > > > ...
> > > > >  
> > > > > > +       *ambient_new_raw = (s16)read_tmp;  
> > > > >  
> > > > > > +       *ambient_old_raw = (s16)read_tmp;  
> > > > >
> > > > > Sorry, did I miss your answer about these castings all over the patch?
> > > > >  
> > > >
> > > > These castings are in fact needed. You read unsigned integer, but the
> > > > return value is signed integer. Without the cast it did not extend the
> > > > signed bit, but just wrote the value to signed. Also I find it more
> > > > obvious with casts, that I did not "accidentally" convert to signed.  
> > >
> > > Should we perhaps be making this explicit for the cases where we
> > > are sign extending?  That doesn't include these two as the lvalue
> > > is s16, but does include some of the others.
> > >
> > > sign_extend32(read_tmp, 15)
> > >  
> >
> > So for you lines like
> > s32 read;
> > read = (read + (s16)read_tmp) / 2;
> >
> > would actually be better as:
> > read = (read + sign_extend32(read_tmp, 15)) / 2;
> >
> > Hm, strange. I would read that more align the read_tmp to 32 bit than
> > the value you have in read_tmp is actually a signed 16 bit integer...
> >  
> 
> OK, I did some trails without the casts and had deja-vu from the first
> series of patches I submitted.  I noticed that without a cast the
> value that ends up in variable is not extended to signed, but it is
> unsigned value truncated. This same finding leads to have these casts
> already in current ambient and object raw read functions.
> 
> So now only debate is if sign_extend32 is useful in this case, as read
> in the current case is 32 bit (before it was also 16 bit).
> 
> My preference is to leave unified across the driver.

It is fairly obvious to me what is going on as things stand, but
if others are being confused, the sign_extend32 does make it explicit
that this is all about sign extension.

> 
> > > >  
> > > > > ...
> > > > >  
> > > > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
> > > > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
> > > > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
> > > > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
> > > > > > +       ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
> > > > > > +       ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);  
> > > > >
> > > > > What so special about these magic 17, 18, 19? Can you provide definitions?
> > > > >  
> > > > When we started 0 to 19 were all open for access, from userspace, then
> > > > only 1 and 2 were used with calculations, and now we use 17, 18 and
> > > > 19. Matter of fact is, I can't provide a descriptive name as it
> > > > depends on DSP version and as you can see now within the same DSP
> > > > version, also on the ID part. While RAM3 vs RAM1 and RAM2 could be
> > > > named RAM_OBJECT1, RAM_OBJECT2, RAM_AMBIENT, knowing our development
> > > > that might not be true in the next configuration, so I rather keep the
> > > > naming as in the datasheet.  
> > > Normal solution for that is to version the defines as well.
> > >
> > > MLX90632_FW3_RAM_1_AMBIENT etc
> > > When a new version changes this, then you introduced new defines to
> > > support that firmware.
> > >  
> >
> > OK will add those, but it is ending up as:
> > MLX90632_RAM_DSP5_AMBIENT
> > MLX90632_RAM_DSP5_EXTENDED_AMBIENT
> > MLX90632_RAM_DSP5_OBJECT_1
> > MLX90632_RAM_DSP5_EXTENDED_OBJECT_1
> > MLX90632_RAM_DSP5_OBJECT_2
> > MLX90632_RAM_DSP5_EXTENDED_OBJECT_2
> >
> > ok?  
That's fine.

> > > >  
> > > > > ...
> > > > >  
> > > > > > +       int tries = 4;  
> > > > >  
> > > > > > +       while (tries-- > 0) {
> > > > > > +               ret = mlx90632_perform_measurement(data);
> > > > > > +               if (ret < 0)
> > > > > > +                       goto read_unlock;
> > > > > > +
> > > > > > +               if (ret == 19)
> > > > > > +                       break;
> > > > > > +       }
> > > > > > +       if (tries < 0) {
> > > > > > +               ret = -ETIMEDOUT;
> > > > > > +               goto read_unlock;
> > > > > > +       }  
> > > > >
> > > > > Please avoid ping-pong type of changes in the same series (similar way
> > > > > as for kernel doc), which means don't introduce something you are
> > > > > going to change later on. Patch to move to do {} while () should go
> > > > > before this one.  
> > > >
> > > > OK, will fix that ordering in v5, but will wait till we solve also
> > > > above discussions to avoid adding new versions.
> > > >  
> > > > >
> > > > > --
> > > > > With Best Regards,
> > > > > Andy Shevchenko  
> > > >
> > > > And about that voodoo stuff with numbers:
> > > >
> > > > Honestly, the equation is in the datasheet[1] and this is just making
> > > > floating point to fixed point with proper intermediate scaling
> > > > (initially I had defines of TENTOX, but that was not desired). There
> > > > is no better explanation of this voodoo.  
> > >
> > > We all love fixed point arithmetic :)
> > >
> > > Jonathan
diff mbox series

Patch

diff --git a/drivers/iio/temperature/mlx90632.c b/drivers/iio/temperature/mlx90632.c
index c3de10ba5b1e..049c1217a166 100644
--- a/drivers/iio/temperature/mlx90632.c
+++ b/drivers/iio/temperature/mlx90632.c
@@ -11,6 +11,7 @@ 
 #include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/kernel.h>
+#include <linux/limits.h>
 #include <linux/module.h>
 #include <linux/math64.h>
 #include <linux/of.h>
@@ -58,6 +59,8 @@ 
 /* Control register address - volatile */
 #define MLX90632_REG_CONTROL	0x3001 /* Control Register address */
 #define   MLX90632_CFG_PWR_MASK		GENMASK(2, 1) /* PowerMode Mask */
+#define   MLX90632_CFG_MTYP_MASK		GENMASK(8, 4) /* Meas select Mask */
+
 /* PowerModes statuses */
 #define MLX90632_PWR_STATUS(ctrl_val) (ctrl_val << 1)
 #define MLX90632_PWR_STATUS_HALT MLX90632_PWR_STATUS(0) /* hold */
@@ -65,6 +68,18 @@ 
 #define MLX90632_PWR_STATUS_STEP MLX90632_PWR_STATUS(2) /* step */
 #define MLX90632_PWR_STATUS_CONTINUOUS MLX90632_PWR_STATUS(3) /* continuous*/
 
+/* Measurement types */
+#define MLX90632_MTYP_MEDICAL 0
+#define MLX90632_MTYP_EXTENDED 17
+
+/* Measurement type select*/
+#define MLX90632_MTYP_STATUS(ctrl_val) (ctrl_val << 4)
+#define MLX90632_MTYP_STATUS_MEDICAL MLX90632_MTYP_STATUS(MLX90632_MTYP_MEDICAL)
+#define MLX90632_MTYP_STATUS_EXTENDED MLX90632_MTYP_STATUS(MLX90632_MTYP_EXTENDED)
+
+/* I2C command register - volatile */
+#define MLX90632_REG_I2C_CMD    0x3005 /* I2C command Register address */
+
 /* Device status register - volatile */
 #define MLX90632_REG_STATUS	0x3fff /* Device status register */
 #define   MLX90632_STAT_BUSY		BIT(10) /* Device busy indicator */
@@ -81,6 +96,8 @@ 
 /* Magic constants */
 #define MLX90632_ID_MEDICAL	0x0105 /* EEPROM DSPv5 Medical device id */
 #define MLX90632_ID_CONSUMER	0x0205 /* EEPROM DSPv5 Consumer device id */
+#define MLX90632_ID_EXTENDED	0x0505 /* EEPROM DSPv5 Extended range device id */
+#define MLX90632_ID_MASK	GENMASK(14, 0) /* DSP version and device ID in EE_VERSION */
 #define MLX90632_DSP_VERSION	5 /* DSP version */
 #define MLX90632_DSP_MASK	GENMASK(7, 0) /* DSP version in EE_VERSION */
 #define MLX90632_RESET_CMD	0x0006 /* Reset sensor (address or global) */
@@ -88,16 +105,20 @@ 
 #define MLX90632_REF_3		12LL /**< ResCtrlRef value of Channel 3 */
 #define MLX90632_MAX_MEAS_NUM	31 /**< Maximum measurements in list */
 #define MLX90632_SLEEP_DELAY_MS 3000 /**< Autosleep delay */
+#define MLX90632_EXTENDED_LIMIT 27000 /* Extended mode raw value limit */
 
 struct mlx90632_data {
 	struct i2c_client *client;
 	struct mutex lock; /* Multiple reads for single measurement */
 	struct regmap *regmap;
 	u16 emissivity;
+	u8 mtyp; /* measurement type - to enable extended range calculations */
+	u32 object_ambient_temperature;
 };
 
 static const struct regmap_range mlx90632_volatile_reg_range[] = {
 	regmap_reg_range(MLX90632_REG_I2C_ADDR, MLX90632_REG_CONTROL),
+	regmap_reg_range(MLX90632_REG_I2C_CMD, MLX90632_REG_I2C_CMD),
 	regmap_reg_range(MLX90632_REG_STATUS, MLX90632_REG_STATUS),
 	regmap_reg_range(MLX90632_RAM_1(0),
 			 MLX90632_RAM_3(MLX90632_MAX_MEAS_NUM)),
@@ -113,6 +134,7 @@  static const struct regmap_range mlx90632_read_reg_range[] = {
 	regmap_reg_range(MLX90632_EE_CTRL, MLX90632_EE_I2C_ADDR),
 	regmap_reg_range(MLX90632_EE_Ha, MLX90632_EE_Hb),
 	regmap_reg_range(MLX90632_REG_I2C_ADDR, MLX90632_REG_CONTROL),
+	regmap_reg_range(MLX90632_REG_I2C_CMD, MLX90632_REG_I2C_CMD),
 	regmap_reg_range(MLX90632_REG_STATUS, MLX90632_REG_STATUS),
 	regmap_reg_range(MLX90632_RAM_1(0),
 			 MLX90632_RAM_3(MLX90632_MAX_MEAS_NUM)),
@@ -199,6 +221,26 @@  static int mlx90632_perform_measurement(struct mlx90632_data *data)
 	return (reg_status & MLX90632_STAT_CYCLE_POS) >> 2;
 }
 
+static int mlx90632_set_meas_type(struct regmap *regmap, u8 type)
+{
+	int ret;
+
+	if ((type != MLX90632_MTYP_MEDICAL) && (type != MLX90632_MTYP_EXTENDED))
+		return -EINVAL;
+
+	ret = regmap_write(regmap, MLX90632_REG_I2C_CMD, MLX90632_RESET_CMD);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write_bits(regmap, MLX90632_REG_CONTROL,
+				 (MLX90632_CFG_MTYP_MASK | MLX90632_CFG_PWR_MASK),
+				 (MLX90632_MTYP_STATUS(type) | MLX90632_PWR_STATUS_HALT));
+	if (ret < 0)
+		return ret;
+
+	return mlx90632_pwr_continuous(regmap);
+}
+
 static int mlx90632_channel_new_select(int perform_ret, uint8_t *channel_new,
 				       uint8_t *channel_old)
 {
@@ -300,6 +342,106 @@  static int mlx90632_read_all_channel(struct mlx90632_data *data,
 	return ret;
 }
 
+static int mlx90632_read_ambient_raw_extended(struct regmap *regmap,
+					      s16 *ambient_new_raw, s16 *ambient_old_raw)
+{
+	unsigned int read_tmp;
+	int ret;
+
+	ret = regmap_read(regmap, MLX90632_RAM_3(17), &read_tmp);
+	if (ret < 0)
+		return ret;
+	*ambient_new_raw = (s16)read_tmp;
+
+	ret = regmap_read(regmap, MLX90632_RAM_3(18), &read_tmp);
+	if (ret < 0)
+		return ret;
+	*ambient_old_raw = (s16)read_tmp;
+
+	return 0;
+}
+
+static int mlx90632_read_object_raw_extended(struct regmap *regmap, s16 *object_new_raw)
+{
+	unsigned int read_tmp;
+	s32 read;
+	int ret;
+
+	ret = regmap_read(regmap, MLX90632_RAM_1(17), &read_tmp);
+	if (ret < 0)
+		return ret;
+	read = (s16)read_tmp;
+
+	ret = regmap_read(regmap, MLX90632_RAM_2(17), &read_tmp);
+	if (ret < 0)
+		return ret;
+	read = read - (s16)read_tmp;
+
+	ret = regmap_read(regmap, MLX90632_RAM_1(18), &read_tmp);
+	if (ret < 0)
+		return ret;
+	read = read - (s16)read_tmp;
+
+	ret = regmap_read(regmap, MLX90632_RAM_2(18), &read_tmp);
+	if (ret < 0)
+		return ret;
+	read = (read + (s16)read_tmp) / 2;
+
+	ret = regmap_read(regmap, MLX90632_RAM_1(19), &read_tmp);
+	if (ret < 0)
+		return ret;
+	read = read + (s16)read_tmp;
+
+	ret = regmap_read(regmap, MLX90632_RAM_2(19), &read_tmp);
+	if (ret < 0)
+		return ret;
+	read = read + (s16)read_tmp;
+
+	if (read > S16_MAX || read < S16_MIN)
+		return -ERANGE;
+
+	*object_new_raw = read;
+
+	return 0;
+}
+
+static int mlx90632_read_all_channel_extended(struct mlx90632_data *data, s16 *object_new_raw,
+					      s16 *ambient_new_raw, s16 *ambient_old_raw)
+{
+	int tries = 4;
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = mlx90632_set_meas_type(data->regmap, MLX90632_MTYP_EXTENDED);
+	if (ret < 0)
+		goto read_unlock;
+
+	while (tries-- > 0) {
+		ret = mlx90632_perform_measurement(data);
+		if (ret < 0)
+			goto read_unlock;
+
+		if (ret == 19)
+			break;
+	}
+	if (tries < 0) {
+		ret = -ETIMEDOUT;
+		goto read_unlock;
+	}
+
+	ret = mlx90632_read_object_raw_extended(data->regmap, object_new_raw);
+	if (ret < 0)
+		goto read_unlock;
+
+	ret = mlx90632_read_ambient_raw_extended(data->regmap, ambient_new_raw, ambient_old_raw);
+
+read_unlock:
+	(void) mlx90632_set_meas_type(data->regmap, MLX90632_MTYP_MEDICAL);
+
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
 static int mlx90632_read_ee_register(struct regmap *regmap, u16 reg_lsb,
 				     s32 *reg_value)
 {
@@ -354,9 +496,23 @@  static s64 mlx90632_preprocess_temp_obj(s16 object_new_raw, s16 object_old_raw,
 	return div64_s64((tmp << 19ULL), 1000LL);
 }
 
+static s64 mlx90632_preprocess_temp_obj_extended(s16 object_new_raw, s16 ambient_new_raw,
+						 s16 ambient_old_raw, s16 Ka)
+{
+	s64 VR_IR, kKa, tmp;
+
+	kKa = ((s64)Ka * 1000LL) >> 10ULL;
+	VR_IR = (s64)ambient_old_raw * 1000000LL +
+		kKa * div64_s64((s64)ambient_new_raw * 1000LL,
+				MLX90632_REF_3);
+	tmp = div64_s64(
+			div64_s64((s64) object_new_raw * 1000000000000LL, MLX90632_REF_12),
+			VR_IR);
+	return div64_s64(tmp << 19ULL, 1000LL);
+}
+
 static s32 mlx90632_calc_temp_ambient(s16 ambient_new_raw, s16 ambient_old_raw,
-				      s32 P_T, s32 P_R, s32 P_G, s32 P_O,
-				      s16 Gb)
+				      s32 P_T, s32 P_R, s32 P_G, s32 P_O, s16 Gb)
 {
 	s64 Asub, Bsub, Ablock, Bblock, Cblock, AMB, sum;
 
@@ -428,6 +584,31 @@  static s32 mlx90632_calc_temp_object(s64 object, s64 ambient, s32 Ea, s32 Eb,
 	return temp;
 }
 
+static s32 mlx90632_calc_temp_object_extended(s64 object, s64 ambient, s64 reflected,
+					      s32 Ea, s32 Eb, s32 Fa, s32 Fb, s32 Ga,
+					      s16 Ha, s16 Hb, u16 tmp_emi)
+{
+	s64 kTA, kTA0, TAdut, TAdut4, Tr4, TaTr4;
+	s64 temp = 25000;
+	s8 i;
+
+	kTA = (Ea * 1000LL) >> 16LL;
+	kTA0 = (Eb * 1000LL) >> 8LL;
+	TAdut = div64_s64(((ambient - kTA0) * 1000000LL), kTA) + 25 * 1000000LL;
+	Tr4 = mlx90632_calc_ta4(reflected, 10);
+	TAdut4 = mlx90632_calc_ta4(TAdut, 10000LL);
+	TaTr4 = Tr4 - div64_s64(Tr4 - TAdut4, tmp_emi) * 1000;
+
+	/* Iterations of calculation as described in datasheet */
+	for (i = 0; i < 5; ++i) {
+		temp = mlx90632_calc_temp_object_iteration(temp, object, TAdut, TaTr4,
+							   Fa / 2, Fb, Ga, Ha, Hb,
+							   tmp_emi);
+	}
+
+	return temp;
+}
+
 static int mlx90632_calc_object_dsp105(struct mlx90632_data *data, int *val)
 {
 	s32 ret;
@@ -475,6 +656,26 @@  static int mlx90632_calc_object_dsp105(struct mlx90632_data *data, int *val)
 	if (ret < 0)
 		return ret;
 
+	if (object_new_raw > MLX90632_EXTENDED_LIMIT &&
+	    data->mtyp == MLX90632_MTYP_EXTENDED) {
+		ret = mlx90632_read_all_channel_extended(data, &object_new_raw,
+							 &ambient_new_raw, &ambient_old_raw);
+		if (ret < 0)
+			return ret;
+
+		/* Use extended mode calculations */
+		ambient = mlx90632_preprocess_temp_amb(ambient_new_raw,
+						       ambient_old_raw, Gb);
+		object = mlx90632_preprocess_temp_obj_extended(object_new_raw,
+							       ambient_new_raw,
+							       ambient_old_raw, Ka);
+		*val = mlx90632_calc_temp_object_extended(object, ambient,
+							  data->object_ambient_temperature,
+							  Ea, Eb, Fa, Fb, Ga,
+							  Ha, Hb, data->emissivity);
+		return 0;
+	}
+
 	ambient = mlx90632_preprocess_temp_amb(ambient_new_raw,
 					       ambient_old_raw, Gb);
 	object = mlx90632_preprocess_temp_obj(object_new_raw,
@@ -648,6 +849,7 @@  static int mlx90632_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, indio_dev);
 	mlx90632->client = client;
 	mlx90632->regmap = regmap;
+	mlx90632->mtyp = MLX90632_MTYP_MEDICAL;
 
 	mutex_init(&mlx90632->lock);
 	indio_dev->name = id->name;
@@ -667,12 +869,17 @@  static int mlx90632_probe(struct i2c_client *client,
 		dev_err(&client->dev, "read of version failed: %d\n", ret);
 		return ret;
 	}
+	read = read & MLX90632_ID_MASK;
 	if (read == MLX90632_ID_MEDICAL) {
 		dev_dbg(&client->dev,
 			"Detected Medical EEPROM calibration %x\n", read);
 	} else if (read == MLX90632_ID_CONSUMER) {
 		dev_dbg(&client->dev,
 			"Detected Consumer EEPROM calibration %x\n", read);
+	} else if (read == MLX90632_ID_EXTENDED) {
+		dev_dbg(&client->dev,
+			"Detected Extended range EEPROM calibration %x\n", read);
+		mlx90632->mtyp = MLX90632_MTYP_EXTENDED;
 	} else if ((read & MLX90632_DSP_MASK) == MLX90632_DSP_VERSION) {
 		dev_dbg(&client->dev,
 			"Detected Unknown EEPROM calibration %x\n", read);	
@@ -684,6 +891,7 @@  static int mlx90632_probe(struct i2c_client *client,
 	}
 
 	mlx90632->emissivity = 1000;
+	mlx90632->object_ambient_temperature = 25000; /* 25 degrees milliCelsius */
 
 	pm_runtime_disable(&client->dev);
 	ret = pm_runtime_set_active(&client->dev);