On 11/14/2025 8:39 PM, Ville Syrjälä wrote:
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.
Hmm.. for PTL+ platforms, the SCL can be in vactive region, at that time
SCL + guardband will become more than vblank.
In that case window1 would be 0.
I believed this is what you were pointing to in [1] or did I miss something.
[1] https://lore.kernel.org/intel-xe/[email protected]/
Regards,
Ankit
+
+ 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
