Hello Jani,
> -----Original Message-----
> From: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Sent: Monday, June 26, 2023 5:53 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>; intel-
> gfx@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH 2/2] drm/i915/color: For MTL convert 24 bit lut
> values to 16 bit
>
> On Mon, 26 Jun 2023, Chaitanya Kumar Borah
> <chaitanya.kumar.borah@xxxxxxxxx> wrote:
> > For MTL and beyond, convert back the 24 bit lut values read from HW to
> > 16 bit values to maintain parity with userspace values. This way we
> > avoid pipe config mismatch for pre-csc lut values.
> >
> > Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/display/intel_color.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_color.c
> > b/drivers/gpu/drm/i915/display/intel_color.c
> > index 25c73e2e6fa3..856191640e71 100644
> > --- a/drivers/gpu/drm/i915/display/intel_color.c
> > +++ b/drivers/gpu/drm/i915/display/intel_color.c
> > @@ -3477,6 +3477,14 @@ static struct drm_property_blob
> *glk_read_degamma_lut(struct intel_crtc *crtc)
> > for (i = 0; i < lut_size; i++) {
> > u32 val = intel_de_read_fw(dev_priv,
> PRE_CSC_GAMC_DATA(pipe));
> >
> > + /*
> > + * For MTL and beyond, convert back the 24 bit lut values
> > + * read from HW to 16 bit values to maintain parity with
> > + * userspace values
> > + */
> > + if (DISPLAY_VER(dev_priv) >= 14)
> > + val = mul_u32_u32(val, (1 << 16)) / (1 << 24);
> > +
>
> Here too please add a small helper for the conversion.
>
Thank you for the comment.
I have sent a new version with a helper function. Please let me know if you see any pitfalls with it.
Regards
Chaitanya.
> BR,
> Jani.
>
> > lut[i].red = val;
> > lut[i].green = val;
> > lut[i].blue = val;
>
> --
> Jani Nikula, Intel Open Source Graphics Center
