> -----Original Message-----
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Sent: Monday, November 20, 2023 7:57 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>
> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH 2/4] drm/i915: Adjust LUT rounding rules
>
> On Mon, Nov 20, 2023 at 06:08:57AM +0000, Borah, Chaitanya Kumar wrote:
> > Hello Ville,
> >
> > > -----Original Message-----
> > > From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf
> > > Of Ville Syrjala
> > > Sent: Friday, October 13, 2023 6:44 PM
> > > To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > Subject: [PATCH 2/4] drm/i915: Adjust LUT rounding rules
> > >
> > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > >
> > > drm_color_lut_extract() rounding was changed to follow the OpenGL
> > > int<-
> > > >float conversion rules. Adjust intel_color_lut_pack() to match.
> > >
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/i915/display/intel_color.c | 14 ++++++--------
> > > 1 file changed, 6 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_color.c
> > > b/drivers/gpu/drm/i915/display/intel_color.c
> > > index 2a2a163ea652..b01f463af861 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_color.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_color.c
> > > @@ -785,14 +785,12 @@ static void chv_assign_csc(struct
> > > intel_crtc_state
> > > *crtc_state)
> > > /* convert hw value with given bit_precision to lut property val */
> > > static u32
> > > intel_color_lut_pack(u32 val, int bit_precision) {
> >
> > Is this operation unique to Intel. Should there be a drm helper for this?
>
> If some other driver gains gamma readout support they could probably use
> something like this. The other option would be to rework the current helper
> to allow conversions both ways.
>
The function name could be a minor inconvenience but anyway until that time arrives.
LGTM.
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
> >
> > Regards
> >
> > Chaitanya
> >
> > > - u32 max = 0xffff >> (16 - bit_precision);
> > > -
> > > - val = clamp_val(val, 0, max);
> > > -
> > > - if (bit_precision < 16)
> > > - val <<= 16 - bit_precision;
> > > -
> > > - return val;
> > > + if (bit_precision > 16)
> > > + return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(val, (1 << 16)
> > > - 1),
> > > + (1 << bit_precision) - 1);
> > > + else
> > > + return DIV_ROUND_CLOSEST(val * ((1 << 16) - 1),
> > > + (1 << bit_precision) - 1);
> > > }
> > >
> > > static u32 i9xx_lut_8(const struct drm_color_lut *color)
> > > --
> > > 2.41.0
> >
>
> --
> Ville Syrjälä
> Intel
