Re: [RESEND, 05/22] drm/i915/vrr: Add DC Balance params to crtc_state

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

On 11/3/2025 10:59 AM, Mitul Golani wrote:
> Add DC Balance params to crtc_state, also add state checker
> params for related properties.
>
> --v3:
> - Seggregate crtc_state params with this patch. (Ankit)
>
> --v4:
> - Update commit message and header. (Ankit)
> - Add +1 to VMIN and VMAX only when it is non-zero. (Ankit)
>
> --v5:
> - Add headers in sorted order. (Jani Nikula)
>
> 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  |  7 ++++++
>   .../drm/i915/display/intel_display_types.h    |  7 ++++++
>   drivers/gpu/drm/i915/display/intel_vrr.c      | 22 +++++++++++++++++++
>   3 files changed, 36 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 42ec78798666..a00625f882e8 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -5470,6 +5470,13 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>   		PIPE_CONF_CHECK_LLI(cmrr.cmrr_m);
>   		PIPE_CONF_CHECK_LLI(cmrr.cmrr_n);
>   		PIPE_CONF_CHECK_BOOL(cmrr.enable);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.vmin);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.vmax);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.guardband);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.slope);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.max_increase);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.max_decrease);
> +		PIPE_CONF_CHECK_I(vrr.dc_balance.vblank_target);
>   	}
>   
>   	if (!fastset || intel_vrr_always_use_vrr_tg(display)) {
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 00600134bda0..33fb70716110 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1358,6 +1358,13 @@ struct intel_crtc_state {
>   		u8 pipeline_full;
>   		u16 flipline, vmin, vmax, guardband;
>   		u32 vsync_end, vsync_start;
> +		struct {
> +			bool enable;
> +			u16 vmin, vmax;
> +			u16 guardband, slope;
> +			u16 max_increase, max_decrease;
> +			u16 vblank_target;
> +		} dc_balance;
>   	} vrr;
>   
>   	/* Content Match Refresh Rate state */
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index 68dde96583c0..3c30c8d3e206 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -9,6 +9,7 @@
>   #include "intel_de.h"
>   #include "intel_display_regs.h"
>   #include "intel_display_types.h"
> +#include "intel_dmc_regs.h"
>   #include "intel_dp.h"
>   #include "intel_psr.h"
>   #include "intel_vrr.h"
> @@ -789,6 +790,8 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
>   {
>   	struct intel_display *display = to_intel_display(crtc_state);
>   	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> +	enum pipe pipe = crtc->pipe;
>   	u32 trans_vrr_ctl, trans_vrr_vsync;
>   	bool vrr_enable;
>   
> @@ -866,6 +869,25 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
>   	else
>   		crtc_state->vrr.enable = vrr_enable;
>   
> +	if (HAS_VRR_DC_BALANCE(display)) {
> +		crtc_state->vrr.dc_balance.vmin =
> +			intel_de_read(display, PIPEDMC_DCB_VMIN(pipe)) ?
> +			intel_de_read(display, PIPEDMC_DCB_VMIN(pipe)) + 1 : 0;

Instead of reading it twice, can we just use a temp variable:

reg = intel_de_read(display, PIPEDMC_DCB_VMIN(pipe)) ;
crtc_state->vrr.dc_balance.vmin = reg ? reg + 1 :0;

reg = intel_de_read(display, PIPEDMC_DCB_VMAX(pipe)) ;
crtc_state->vrr.dc_balance.vmax = reg ? reg + 1 :0;


Regards,

Ankit

> +		crtc_state->vrr.dc_balance.vmax =
> +			intel_de_read(display, PIPEDMC_DCB_VMAX(pipe)) ?
> +			intel_de_read(display, PIPEDMC_DCB_VMAX(pipe)) + 1 : 0;
> +		crtc_state->vrr.dc_balance.guardband =
> +			intel_de_read(display, PIPEDMC_DCB_GUARDBAND(pipe));
> +		crtc_state->vrr.dc_balance.max_increase =
> +			intel_de_read(display, PIPEDMC_DCB_MAX_INCREASE(pipe));
> +		crtc_state->vrr.dc_balance.max_decrease =
> +			intel_de_read(display, PIPEDMC_DCB_MAX_DECREASE(pipe));
> +		crtc_state->vrr.dc_balance.slope =
> +			intel_de_read(display, PIPEDMC_DCB_SLOPE(pipe));
> +		crtc_state->vrr.dc_balance.vblank_target =
> +			intel_de_read(display, PIPEDMC_DCB_VBLANK(pipe));
> +	}
> +
>   	/*
>   	 * #TODO: For Both VRR and CMRR the flag I915_MODE_FLAG_VRR is set for mode_flags.
>   	 * Since CMRR is currently disabled, set this flag for VRR for now.