diff mbox series

[v2] iio: sx9310: Fix semtech,avg-pos-strength setting when > 16

Message ID 20201120182944.543428-1-swboyd@chromium.org (mailing list archive)
State New, archived
Headers show
Series [v2] iio: sx9310: Fix semtech,avg-pos-strength setting when > 16 | expand

Commit Message

Stephen Boyd Nov. 20, 2020, 6:29 p.m. UTC 
This DT property can be 0, 16, and then 64, but not 32. The math here
doesn't recognize this slight bump in the power of 2 numbers and
translates a DT property of 64 into the register value '3' when it
really should be '2'. Fix it by subtracting one more if the number being
translated is larger than 16.

Cc: Daniel Campello <campello@chromium.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Evan Green <evgreen@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---

Changes from v1 (https://lore.kernel.org/r/20201120073842.3232458-1-swboyd@chromium.org):
 * Changed ternary to consider 17 to 31 as the same as 16

 drivers/iio/proximity/sx9310.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


base-commit: 5b19ca2c78a0838976064c0347e46a2c859b541d

Comments

Doug Anderson Nov. 20, 2020, 6:31 p.m. UTC | #1 
Hi,

On Fri, Nov 20, 2020 at 10:29 AM Stephen Boyd <swboyd@chromium.org> wrote:
>
> This DT property can be 0, 16, and then 64, but not 32. The math here
> doesn't recognize this slight bump in the power of 2 numbers and
> translates a DT property of 64 into the register value '3' when it
> really should be '2'. Fix it by subtracting one more if the number being
> translated is larger than 16.
>
> Cc: Daniel Campello <campello@chromium.org>
> Cc: Lars-Peter Clausen <lars@metafoo.de>
> Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
> Cc: Douglas Anderson <dianders@chromium.org>
> Cc: Gwendal Grignou <gwendal@chromium.org>
> Cc: Evan Green <evgreen@chromium.org>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
>
> Changes from v1 (https://lore.kernel.org/r/20201120073842.3232458-1-swboyd@chromium.org):
>  * Changed ternary to consider 17 to 31 as the same as 16
>
>  drivers/iio/proximity/sx9310.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Jonathan Cameron Nov. 21, 2020, 2:58 p.m. UTC | #2 
On Fri, 20 Nov 2020 10:29:44 -0800
Stephen Boyd <swboyd@chromium.org> wrote:

> This DT property can be 0, 16, and then 64, but not 32. The math here
> doesn't recognize this slight bump in the power of 2 numbers and
> translates a DT property of 64 into the register value '3' when it
> really should be '2'. Fix it by subtracting one more if the number being
> translated is larger than 16.
> 
> Cc: Daniel Campello <campello@chromium.org>
> Cc: Lars-Peter Clausen <lars@metafoo.de>
> Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
> Cc: Douglas Anderson <dianders@chromium.org>
> Cc: Gwendal Grignou <gwendal@chromium.org>
> Cc: Evan Green <evgreen@chromium.org>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
> 
> Changes from v1 (https://lore.kernel.org/r/20201120073842.3232458-1-swboyd@chromium.org):
>  * Changed ternary to consider 17 to 31 as the same as 16
> 
>  drivers/iio/proximity/sx9310.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> index a2f820997afc..ee1b4ff05a37 100644
> --- a/drivers/iio/proximity/sx9310.c
> +++ b/drivers/iio/proximity/sx9310.c
> @@ -1305,7 +1305,7 @@ sx9310_get_default_reg(struct sx9310_data *data, int i,
>  		if (ret)
>  			break;
>  
> -		pos = min(max(ilog2(pos), 3), 10) - 3;
> +		pos = min(max(ilog2(pos), 3), 11) - (pos >= 32 ? 4 : 3);

Given this is now rather tricky to read, I'd just do an explicit lookup of
the allowed values.  Probably just a switch statement.

Thanks,

Jonathan

>  		reg_def->def &= ~SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK;
>  		reg_def->def |= FIELD_PREP(SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK,
>  					   pos);
> 
> base-commit: 5b19ca2c78a0838976064c0347e46a2c859b541d
Jonathan Cameron Nov. 21, 2020, 3:02 p.m. UTC | #3 
On Sat, 21 Nov 2020 14:58:49 +0000
Jonathan Cameron <jic23@kernel.org> wrote:

> On Fri, 20 Nov 2020 10:29:44 -0800
> Stephen Boyd <swboyd@chromium.org> wrote:
> 
> > This DT property can be 0, 16, and then 64, but not 32. The math here
> > doesn't recognize this slight bump in the power of 2 numbers and
> > translates a DT property of 64 into the register value '3' when it
> > really should be '2'. Fix it by subtracting one more if the number being
> > translated is larger than 16.
> > 
> > Cc: Daniel Campello <campello@chromium.org>
> > Cc: Lars-Peter Clausen <lars@metafoo.de>
> > Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
> > Cc: Douglas Anderson <dianders@chromium.org>
> > Cc: Gwendal Grignou <gwendal@chromium.org>
> > Cc: Evan Green <evgreen@chromium.org>
> > Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> > ---
> > 
> > Changes from v1 (https://lore.kernel.org/r/20201120073842.3232458-1-swboyd@chromium.org):
> >  * Changed ternary to consider 17 to 31 as the same as 16
> > 
> >  drivers/iio/proximity/sx9310.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> > index a2f820997afc..ee1b4ff05a37 100644
> > --- a/drivers/iio/proximity/sx9310.c
> > +++ b/drivers/iio/proximity/sx9310.c
> > @@ -1305,7 +1305,7 @@ sx9310_get_default_reg(struct sx9310_data *data, int i,
> >  		if (ret)
> >  			break;
> >  
> > -		pos = min(max(ilog2(pos), 3), 10) - 3;
> > +		pos = min(max(ilog2(pos), 3), 11) - (pos >= 32 ? 4 : 3);  
> 
> Given this is now rather tricky to read, I'd just do an explicit lookup of
> the allowed values.  Probably just a switch statement.
As an alternative, a comment would help saying that it's powers of 2 except
for a gap at 64.

Thanks,

J

> 
> Thanks,
> 
> Jonathan
> 
> >  		reg_def->def &= ~SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK;
> >  		reg_def->def |= FIELD_PREP(SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK,
> >  					   pos);
> > 
> > base-commit: 5b19ca2c78a0838976064c0347e46a2c859b541d  
>
Stephen Boyd Dec. 2, 2020, 7:32 p.m. UTC | #4 
Quoting Jonathan Cameron (2020-11-21 07:02:45)
> On Sat, 21 Nov 2020 14:58:49 +0000
> Jonathan Cameron <jic23@kernel.org> wrote:
> 
> > On Fri, 20 Nov 2020 10:29:44 -0800
> > Stephen Boyd <swboyd@chromium.org> wrote:
> > > diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> > > index a2f820997afc..ee1b4ff05a37 100644
> > > --- a/drivers/iio/proximity/sx9310.c
> > > +++ b/drivers/iio/proximity/sx9310.c
> > > @@ -1305,7 +1305,7 @@ sx9310_get_default_reg(struct sx9310_data *data, int i,
> > >             if (ret)
> > >                     break;
> > >  
> > > -           pos = min(max(ilog2(pos), 3), 10) - 3;
> > > +           pos = min(max(ilog2(pos), 3), 11) - (pos >= 32 ? 4 : 3);  
> > 
> > Given this is now rather tricky to read, I'd just do an explicit lookup of
> > the allowed values.  Probably just a switch statement.
> As an alternative, a comment would help saying that it's powers of 2 except
> for a gap at 64.
> 

Ok. I'll update with a comment.
diff mbox series

Patch

diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
index a2f820997afc..ee1b4ff05a37 100644
--- a/drivers/iio/proximity/sx9310.c
+++ b/drivers/iio/proximity/sx9310.c
@@ -1305,7 +1305,7 @@  sx9310_get_default_reg(struct sx9310_data *data, int i,
 		if (ret)
 			break;
 
-		pos = min(max(ilog2(pos), 3), 10) - 3;
+		pos = min(max(ilog2(pos), 3), 11) - (pos >= 32 ? 4 : 3);
 		reg_def->def &= ~SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK;
 		reg_def->def |= FIELD_PREP(SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK,
 					   pos);