Re: [PATCH 2/6] drm/i915/panel: Preserve Vtotal-Vsync distance while adjusting vtotal

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

On Fri, May 22, 2026 at 06:55:07PM +0530, Ankit Nautiyal wrote:
> As we increase the vtotal to accommodate lower resfresh rate for fixed
> modes, adjust the vtotal-vsync distance also.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_panel.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
> index 20c548eea6da..14c7eea8ccb1 100644
> --- a/drivers/gpu/drm/i915/display/intel_panel.c
> +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> @@ -237,11 +237,18 @@ int intel_panel_compute_config(struct intel_connector *connector,
>  
>  	drm_mode_copy(adjusted_mode, fixed_mode);
>  
> -	if (is_vrr && fixed_mode_vrefresh != vrefresh)
> +	if (is_vrr && fixed_mode_vrefresh != vrefresh) {
> +		int vsync_start_diff = adjusted_mode->vtotal - adjusted_mode->vsync_start;
> +		int vsync_end_diff = adjusted_mode->vtotal - adjusted_mode->vsync_end;

I'd probably just drop the "_diff" part from the variable names.
It makes me think of a difference between the vsync pulse in
two modes or something.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
>  		adjusted_mode->vtotal =
>  			DIV_ROUND_CLOSEST(adjusted_mode->clock * 1000,
>  					  adjusted_mode->htotal * vrefresh);
>  
> +		adjusted_mode->vsync_start = adjusted_mode->vtotal - vsync_start_diff;
> +		adjusted_mode->vsync_end = adjusted_mode->vtotal - vsync_end_diff;
> +	}
> +
>  	drm_mode_set_crtcinfo(adjusted_mode, 0);
>  
>  	return 0;
> -- 
> 2.45.2

-- 
Ville Syrjälä
Intel