> -----Original Message-----
> From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Ville
> Syrjala
> Sent: Tuesday, June 25, 2024 12:40 AM
> To: intel-gfx@lists.freedesktop.org
> Subject: [PATCH 10/14] drm/i915/dsb: Introduce intel_dsb_chain()
>
> From: Ville Syrjälä <ville.syrj...@linux.intel.com>
>
> 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?
>
> Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> ---
> 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.
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
