Re: [PATCH v9 09/17] drm/i915/display: Add DC Balance flip count operations

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 11/27/2025 2:46 PM, Mitul Golani wrote:
> Track dc balance flip count with params per crtc. Increment
> DC Balance Flip count before every flip to indicate DMC
> firmware about new flip occurrence which needs to be adjusted
> for dc balancing. This is tracked separately from legacy
> FLIP_COUNT register also Reset DC balance flip count value
> while disabling VRR adaptive mode, this is to start with
> fresh counts when VRR adaptive refresh mode is triggered again.
>
> --v2:
> - Call during intel_update_crtc.(Ankit)
>
> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>

Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>


> ---
>   drivers/gpu/drm/i915/display/intel_display.c      |  3 +++
>   .../gpu/drm/i915/display/intel_display_types.h    |  4 ++++
>   drivers/gpu/drm/i915/display/intel_vrr.c          | 15 +++++++++++++++
>   drivers/gpu/drm/i915/display/intel_vrr.h          |  2 ++
>   4 files changed, 24 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index d41ab965c013..1269f841d48b 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -6863,6 +6863,9 @@ static void intel_update_crtc(struct intel_atomic_state *state,
>   		intel_crtc_update_active_timings(new_crtc_state,
>   						 new_crtc_state->vrr.enable);
>   
> +	if (new_crtc_state->vrr.dc_balance.enable)
> +		intel_vrr_dcb_increment_flip_count(new_crtc_state, crtc);
> +
>   	/*
>   	 * We usually enable FIFO underrun interrupts as part of the
>   	 * CRTC enable sequence during modesets.  But when we inherit a
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 8eb0ace7d918..740c5fc9fe1e 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1501,6 +1501,10 @@ struct intel_crtc {
>   		struct intel_link_m_n m_n, m2_n2;
>   	} drrs;
>   
> +	struct {
> +		u64 flip_count;
> +	} dc_balance;
> +
>   	int scanline_offset;
>   
>   	struct {
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index ff65c1167e1b..411ae5da3824 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -632,6 +632,20 @@ void intel_vrr_set_transcoder_timings(const struct intel_crtc_state *crtc_state)
>   			       EMP_AS_SDP_DB_TL(crtc_state->vrr.vsync_start));
>   }
>   
> +void
> +intel_vrr_dcb_increment_flip_count(struct intel_crtc_state *crtc_state,
> +				   struct intel_crtc *crtc)
> +{
> +	struct intel_display *display = to_intel_display(crtc_state);
> +	enum pipe pipe = crtc->pipe;
> +
> +	if (!crtc_state->vrr.dc_balance.enable)
> +		return;
> +
> +	intel_de_write(display, PIPEDMC_DCB_FLIP_COUNT(pipe),
> +		       ++crtc->dc_balance.flip_count);
> +}
> +
>   void
>   intel_vrr_dcb_reset(const struct intel_crtc_state *old_crtc_state,
>   		    struct intel_crtc *crtc)
> @@ -642,6 +656,7 @@ intel_vrr_dcb_reset(const struct intel_crtc_state *old_crtc_state,
>   	if (!old_crtc_state->vrr.dc_balance.enable)
>   		return;
>   
> +	intel_de_write(display, PIPEDMC_DCB_FLIP_COUNT(pipe), 0);
>   	intel_de_write(display, PIPEDMC_DCB_BALANCE_RESET(pipe), 0);
>   }
>   
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.h b/drivers/gpu/drm/i915/display/intel_vrr.h
> index d40ed5504180..bedcc8c4bff2 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.h
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.h
> @@ -29,6 +29,8 @@ void intel_vrr_send_push(struct intel_dsb *dsb,
>   			 const struct intel_crtc_state *crtc_state);
>   void intel_vrr_check_push_sent(struct intel_dsb *dsb,
>   			       const struct intel_crtc_state *crtc_state);
> +void intel_vrr_dcb_increment_flip_count(struct intel_crtc_state *crtc_state,
> +					struct intel_crtc *crtc);
>   bool intel_vrr_is_push_sent(const struct intel_crtc_state *crtc_state);
>   void intel_vrr_disable(const struct intel_crtc_state *old_crtc_state);
>   void intel_vrr_get_config(struct intel_crtc_state *crtc_state);