[PATCH 2/2] drm/i915/display: Don't wait for vblank for LUT DSB programming

[Borah, Chaitanya Kumar]

Thank you, Jani, for the review.

> -----Original Message-----
> From: Jani Nikula <jani.nikula at linux.intel.com>
> Sent: Thursday, February 27, 2025 6:11 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>; intel-
> xe at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
> Cc: ville.syrjala at linux.intel.com; Shankar, Uma <uma.shankar at intel.com>;
> Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>
> Subject: Re: [PATCH 2/2] drm/i915/display: Don't wait for vblank for LUT DSB
> programming
> 
> On Tue, 25 Feb 2025, Chaitanya Kumar Borah
> <chaitanya.kumar.borah at intel.com> wrote:
> > From PTL, LUT registers are made double buffered. With this change, we
> > don't need to wait for vblank to program them. Start DSB1 for
> > programming them without waiting for vblank.
> >
> > Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 919e236a9650..9c3fdfcd6759 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -7352,6 +7352,7 @@ static void intel_atomic_dsb_finish(struct
> > intel_atomic_state *state,  {
> >  	struct intel_crtc_state *new_crtc_state =
> >  		intel_atomic_get_new_crtc_state(state, crtc);
> > +	struct intel_display *display = to_intel_display(state);
> 
> Please always put display local variable first.
> 

Ack.
What about the cases it is dependent on other local variables. Should we put it immediately after them?

> >
> >  	if (!new_crtc_state->use_dsb && !new_crtc_state->dsb_color_vblank)
> >  		return;
> > @@ -7408,7 +7409,8 @@ static void intel_atomic_dsb_finish(struct
> > intel_atomic_state *state,
> >
> >  	if (new_crtc_state->dsb_color_vblank)
> >  		intel_dsb_chain(state, new_crtc_state->dsb_commit,
> > -				new_crtc_state->dsb_color_vblank, true);
> > +				new_crtc_state->dsb_color_vblank,
> > +				HAS_DOUBLE_BUFFERED_LUT(display) ? false
> : true);
> 
> HAS_DOUBLE_BUFFERED_LUT(display) ? false : true
> 
> =>
> 
> !HAS_DOUBLE_BUFFERED_LUT(display)
> 

Ack.

Regards

Chaitanya

> 
> >
> >  	intel_dsb_finish(new_crtc_state->dsb_commit);
> >  }
> 
> --
> Jani Nikula, Intel