> -----Original Message-----
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Sent: Wednesday, July 3, 2024 5:50 PM
> To: Manna, Animesh <animesh.manna@xxxxxxxxx>
> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH 10/14] drm/i915/dsb: Introduce intel_dsb_chain()
>
> On Wed, Jul 03, 2024 at 12:10:38PM +0000, Manna, Animesh wrote:
> >
> >
> > > -----Original Message-----
> > > From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf
> > > Of Ville Syrjala
> > > Sent: Tuesday, June 25, 2024 12:40 AM
> > > To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > > Subject: [PATCH 10/14] drm/i915/dsb: Introduce intel_dsb_chain()
> > >
> > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > >
> > > In order to handle the DEwake tricks without involving the CPU we
> > > need a mechanism by which one DSB can start another one. Add a basic
> > > function to do so. We'll extend it later with additional code to actually
> deal with DEwake.
> >
> > Is chained DSB concept restricting to only 2 DSB instance or can be
> extended to available/max DSB instances?
> >
> > Are we exposing full chain of DSB to user or can be restrict to primary DSB
> which will control other instances?
>
> You can start any DSB from any other DSB.
>
> > >
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/i915/display/intel_dsb.c | 42
> > > ++++++++++++++++++++++++ drivers/gpu/drm/i915/display/intel_dsb.h |
> > > 3 ++
> > > 2 files changed, 45 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c
> > > b/drivers/gpu/drm/i915/display/intel_dsb.c
> > > index 092cf082ac39..4c0519c41f16 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> > > @@ -502,6 +502,48 @@ static u32 dsb_error_int_en(struct
> > > intel_display
> > > *display)
> > > return errors;
> > > }
> > >
> > > +static void _intel_dsb_chain(struct intel_atomic_state *state,
> > > + struct intel_dsb *dsb,
> > > + struct intel_dsb *chained_dsb,
> > > + u32 ctrl)
> >
> > I do not see any usage of ctrl variable in this patch, maybe good to add
> wherever will be using it.
>
> It's in the next patch.
If we agree that intel_dsb_chain() will always work with DSB_WAIT_FOR_VBLANK, this ctrl variable will not be needed.
Regards,
Animesh
>
> >
> > Regards,
> > Animesh
> > > +{
> > > + struct intel_display *display = to_intel_display(state->base.dev);
> > > + struct intel_crtc *crtc = dsb->crtc;
> > > + enum pipe pipe = crtc->pipe;
> > > + u32 tail;
> > > +
> > > + if (drm_WARN_ON(display->drm, dsb->id == chained_dsb->id))
> > > + return;
> > > +
> > > + tail = chained_dsb->free_pos * 4;
> > > + if (drm_WARN_ON(display->drm, !IS_ALIGNED(tail,
> > > CACHELINE_BYTES)))
> > > + return;
> > > +
> > > + intel_dsb_reg_write(dsb, DSB_CTRL(pipe, chained_dsb->id),
> > > + ctrl | DSB_ENABLE);
> > > +
> > > + intel_dsb_reg_write(dsb, DSB_CHICKEN(pipe, chained_dsb->id),
> > > + dsb_chicken(state, crtc));
> > > +
> > > + intel_dsb_reg_write(dsb, DSB_INTERRUPT(pipe, chained_dsb->id),
> > > + dsb_error_int_status(display) |
> > > DSB_PROG_INT_STATUS |
> > > + dsb_error_int_en(display));
> > > +
> > > + intel_dsb_reg_write(dsb, DSB_HEAD(pipe, chained_dsb->id),
> > > + intel_dsb_buffer_ggtt_offset(&chained_dsb-
> > > >dsb_buf));
> > > +
> > > + intel_dsb_reg_write(dsb, DSB_TAIL(pipe, chained_dsb->id),
> > > + intel_dsb_buffer_ggtt_offset(&chained_dsb-
> > > >dsb_buf) + tail); }
> > > +
> > > +void intel_dsb_chain(struct intel_atomic_state *state,
> > > + struct intel_dsb *dsb,
> > > + struct intel_dsb *chained_dsb) {
> > > + _intel_dsb_chain(state, dsb, chained_dsb,
> > > + 0);
> > > +}
> > > +
> > > static void _intel_dsb_commit(struct intel_dsb *dsb, u32 ctrl,
> > > int hw_dewake_scanline)
> > > {
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dsb.h
> > > b/drivers/gpu/drm/i915/display/intel_dsb.h
> > > index d0737cefb393..e59fd7da0fc0 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dsb.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_dsb.h
> > > @@ -45,6 +45,9 @@ void intel_dsb_wait_scanline_in(struct
> > > intel_atomic_state *state, void intel_dsb_wait_scanline_out(struct
> > > intel_atomic_state *state,
> > > struct intel_dsb *dsb,
> > > int lower, int upper);
> > > +void intel_dsb_chain(struct intel_atomic_state *state,
> > > + struct intel_dsb *dsb,
> > > + struct intel_dsb *chained_dsb);
> > >
> > > void intel_dsb_commit(struct intel_dsb *dsb,
> > > bool wait_for_vblank);
> > > --
> > > 2.44.2
> >
>
> --
> Ville Syrjälä
> Intel
