Re: [Intel-gfx] [PATCH] drm/i915/display/vrr: Compute VRR min/max based on highest clock mode for DRRS panel

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Aug 23, 2023 at 11:51:59PM +0000, Manasi Navare wrote:
> In case of a DRRS panel, there is a preferred panel mode and there is
> a downclock mode with lower pixel clock. But the Vtotal for both remains
> the same. This means even in downclocking mode the VRR Vtotal min/max
> should remain the same.
> So in this case always use the highest clock mode to compute VRR
> parameters.

NAK. The VRR parameters must be calculated based on the actual timings
used. Trying to make seamless DRRS and VRR coexist nicely might be a
doomed idea. Not 100% sure though since I haven't really thought
through all the combinations.

> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Manasi Navare <navaremanasi@chromium.org>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c  | 4 ++--
>  drivers/gpu/drm/i915/display/intel_dp.h  | 2 ++
>  drivers/gpu/drm/i915/display/intel_vrr.c | 7 ++++---
>  3 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 7067ee3a4bd3..c572a018ce57 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1509,8 +1509,8 @@ static bool has_seamless_m_n(struct intel_connector *connector)
>  		intel_panel_drrs_type(connector) == DRRS_TYPE_SEAMLESS;
>  }
>  
> -static int intel_dp_mode_clock(const struct intel_crtc_state *crtc_state,
> -			       const struct drm_connector_state *conn_state)
> +int intel_dp_mode_clock(const struct intel_crtc_state *crtc_state,
> +			const struct drm_connector_state *conn_state)
>  {
>  	struct intel_connector *connector = to_intel_connector(conn_state->connector);
>  	const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
> index 788a577ebe16..3c9866356359 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> @@ -119,6 +119,8 @@ u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
>  				bool bigjoiner);
>  bool intel_dp_need_bigjoiner(struct intel_dp *intel_dp,
>  			     int hdisplay, int clock);
> +int intel_dp_mode_clock(const struct intel_crtc_state *crtc_state,
> +			const struct drm_connector_state *conn_state);
>  
>  static inline unsigned int intel_dp_unused_lane_mask(int lane_count)
>  {
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index 88e4759b538b..18a4e0e4e696 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -8,6 +8,7 @@
>  #include "i915_reg.h"
>  #include "intel_de.h"
>  #include "intel_display_types.h"
> +#include "intel_dp.h"
>  #include "intel_vrr.h"
>  
>  bool intel_vrr_is_capable(struct intel_connector *connector)
> @@ -106,7 +107,7 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>  		to_intel_connector(conn_state->connector);
>  	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
>  	const struct drm_display_info *info = &connector->base.display_info;
> -	int vmin, vmax;
> +	int vmin, vmax, clock = intel_dp_mode_clock(crtc_state, conn_state);
>  
>  	if (!intel_vrr_is_capable(connector))
>  		return;
> @@ -114,9 +115,9 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE)
>  		return;
>  
> -	vmin = DIV_ROUND_UP(adjusted_mode->crtc_clock * 1000,
> +	vmin = DIV_ROUND_UP(clock * 1000,
>  			    adjusted_mode->crtc_htotal * info->monitor_range.max_vfreq);
> -	vmax = adjusted_mode->crtc_clock * 1000 /
> +	vmax = clock * 1000 /
>  		(adjusted_mode->crtc_htotal * info->monitor_range.min_vfreq);
>  
>  	vmin = max_t(int, vmin, adjusted_mode->crtc_vtotal);
> -- 
> 2.42.0.rc1.204.g551eb34607-goog

-- 
Ville Syrjälä
Intel