Re: [PATCH v2] drm/i915/display: Take into account AS SDP in intel_dp_sdp_min_guardband

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

On Thu, Oct 23, 2025 at 07:31:40AM +0300, Jouni Högander wrote:
> We started seeing "[drm] *ERROR* Timed out waiting PSR idle state" after
> taking optimized guardband into use. These are seen because VSC SDPs are
> sent on same line as AS SDPs when AS SDP is enabled. AS SDP is sent on line
> configured in EMP_AS_SDP_TL register. We are configuring
> crtc_state->vrr.vsync_start into that register.
> 
> Fix this by ensuring AS SDP is sent on line which is within
> guardband. From the bspec:
> 
> EMP_AS_SDP_TL < SCL + Guardband
> 
> v2: check HAS_AS_SDP
> 
> Bspec: 71197
> Fixes: 52ecd48b8d3f ("drm/i915/dp: Add helper to get min sdp guardband")
> Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>

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

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 475518b4048b7..a3391b17571cf 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -7023,7 +7023,7 @@ int intel_dp_compute_config_late(struct intel_encoder *encoder,
>  }
>  
>  static
> -int intel_dp_get_lines_for_sdp(u32 type)
> +int intel_dp_get_lines_for_sdp(const struct intel_crtc_state *crtc_state, u32 type)
>  {
>  	switch (type) {
>  	case DP_SDP_VSC_EXT_VESA:
> @@ -7033,6 +7033,8 @@ int intel_dp_get_lines_for_sdp(u32 type)
>  		return 8;
>  	case DP_SDP_PPS:
>  		return 7;
> +	case DP_SDP_ADAPTIVE_SYNC:
> +		return crtc_state->vrr.vsync_start + 1;
>  	default:
>  		break;
>  	}
> @@ -7043,17 +7045,25 @@ int intel_dp_get_lines_for_sdp(u32 type)
>  int intel_dp_sdp_min_guardband(const struct intel_crtc_state *crtc_state,
>  			       bool assume_all_enabled)
>  {
> +	struct intel_display *display = to_intel_display(crtc_state);
>  	int sdp_guardband = 0;
>  
>  	if (assume_all_enabled ||
>  	    crtc_state->infoframes.enable &
>  	    intel_hdmi_infoframe_enable(HDMI_PACKET_TYPE_GAMUT_METADATA))
>  		sdp_guardband = max(sdp_guardband,
> -				    intel_dp_get_lines_for_sdp(HDMI_PACKET_TYPE_GAMUT_METADATA));
> +				    intel_dp_get_lines_for_sdp(crtc_state,
> +							       HDMI_PACKET_TYPE_GAMUT_METADATA));
>  
>  	if (assume_all_enabled ||
>  	    crtc_state->dsc.compression_enable)
> -		sdp_guardband = max(sdp_guardband, intel_dp_get_lines_for_sdp(DP_SDP_PPS));
> +		sdp_guardband = max(sdp_guardband,
> +				    intel_dp_get_lines_for_sdp(crtc_state, DP_SDP_PPS));
> +
> +	if ((assume_all_enabled && HAS_AS_SDP(display)) ||
> +	    crtc_state->infoframes.enable & intel_hdmi_infoframe_enable(DP_SDP_ADAPTIVE_SYNC))
> +		sdp_guardband = max(sdp_guardband,
> +				    intel_dp_get_lines_for_sdp(crtc_state, DP_SDP_ADAPTIVE_SYNC));
>  
>  	return sdp_guardband;
>  }
> -- 
> 2.43.0

-- 
Ville Syrjälä
Intel