On Fri, Nov 14, 2025 at 10:57:43AM +0530, Ankit Nautiyal wrote:
> LOBF must be disabled if the number of lines within Window 1 is not greater
> than ALPM_CTL[ALPM Entry Check]
>
> v2: Consider the case where SCL is in the active region. (Ville)
>
> Bspec:71041
> Signed-off-by: Ankit Nautiyal <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_alpm.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 98cbf5dde73b..686e4d13f864 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -263,6 +263,23 @@ int intel_alpm_lobf_min_guardband(struct
> intel_crtc_state *crtc_state)
> return first_sdp_position + waketime_in_lines +
> crtc_state->set_context_latency;
> }
>
> +static bool intel_alpm_lobf_is_window1_sufficient(struct intel_crtc_state
> *crtc_state)
> +{
> + struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
> + int vblank = adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vdisplay;
> + int window1;
> +
> + /*
> + * LOBF must be disabled if the number of lines within Window 1 is not
> + * greater than ALPM_CTL[ALPM Entry Check]
> + */
> + window1 = vblank - min(vblank,
> + crtc_state->vrr.guardband +
> + crtc_state->set_context_latency);
Dunno why you have the min() here? guardband+SCL can never
exceed the total vblank length.
> +
> + return window1 > crtc_state->alpm_state.check_entry_lines;
> +}
> +
> void intel_alpm_lobf_compute_config_late(struct intel_dp *intel_dp,
> struct intel_crtc_state *crtc_state)
> {
> @@ -272,6 +289,11 @@ void intel_alpm_lobf_compute_config_late(struct intel_dp
> *intel_dp,
> if (!crtc_state->has_lobf)
> return;
>
> + if (!intel_alpm_lobf_is_window1_sufficient(crtc_state)) {
> + crtc_state->has_lobf = false;
> + return;
> + }
> +
> /*
> * LOBF can only be enabled if the time from the start of the
> SCL+Guardband
> * window to the position of the first SDP is greater than the time it
> takes
> --
> 2.45.2
--
Ville Syrjälä
Intel
