Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
drm/i915/alpm: Compute LOBF late after guardband is already determined
Currently intel_alpm_lobf_compute_config() tries to account for
guardband +SCL requirements during encoder->compute_config() phase,
even before guardband is computed.
Also, LOBF depends on crtc_state->has_psr which can be modified in
encoder->compute_config_late().
Account for lobf requirements while optimizing the guardband and add
checks for final guardband in encoder->compute_config_late() phase after
the guardband and the final state of crtc_state->has_psr are already
computed.
Use crtc_state->vrr.guardband and crtc_state->set_context_latency for
the computation and add more documentation for the dependency of first
sdp position, guardband, set context latency and wake lines.
v2: Add helper to use min guardband required for lobf.
v3: Remove unrelated inadvertent changes. (Michał)
v4: Add a #FIXME note for computing wakelines based on feature. (Jouni)
Bspec:71041
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20260204050250.762718-2-ankit.k.nautiyal@intel.com
+63
-14
+56
-14
drivers/gpu/drm/i915/display/intel_alpm.c
+56
-14
drivers/gpu/drm/i915/display/intel_alpm.c
···
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#include "intel_dp_aux.h"
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#include "intel_psr.h"
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#include "intel_psr_regs.h"
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#include "intel_vrr.h"
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#define SILENCE_PERIOD_MIN_TIME 80
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#define SILENCE_PERIOD_MAX_TIME 180
···
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return true;
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}
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int intel_alpm_lobf_min_guardband(struct intel_crtc_state *crtc_state)
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{
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struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
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int first_sdp_position = adjusted_mode->crtc_vtotal -
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adjusted_mode->crtc_vsync_start;
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int waketime_in_lines;
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+
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/*
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* #FIXME: Need to check if io_wake_lines or aux_less_wake_lines
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* is applicable. Currently this information is not readily
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* available in crtc_state, so max will suffice for now.
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*/
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waketime_in_lines = max(crtc_state->alpm_state.io_wake_lines,
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crtc_state->alpm_state.aux_less_wake_lines);
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+
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if (!crtc_state->has_lobf)
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return 0;
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+
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return first_sdp_position + waketime_in_lines + crtc_state->set_context_latency;
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}
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+
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void intel_alpm_lobf_compute_config_late(struct intel_dp *intel_dp,
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struct intel_crtc_state *crtc_state)
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{
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struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
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int waketime_in_lines, first_sdp_position;
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+
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if (!crtc_state->has_lobf)
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return;
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+
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/*
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* LOBF can only be enabled if the time from the start of the SCL+Guardband
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* window to the position of the first SDP is greater than the time it takes
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* to wake the main link.
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*
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* Position of first sdp : vsync_start
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* start of scl + guardband : vtotal - (scl + guardband)
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* time in lines to wake main link : waketime_in_lines
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*
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* Position of first sdp - start of (scl + guardband) > time in lines to wake main link
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* vsync_start - (vtotal - (scl + guardband)) > waketime_in_lines
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* vsync_start - vtotal + scl + guardband > waketime_in_lines
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* scl + guardband > waketime_in_lines + (vtotal - vsync_start)
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*/
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first_sdp_position = adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vsync_start;
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if (intel_alpm_aux_less_wake_supported(intel_dp))
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waketime_in_lines = crtc_state->alpm_state.io_wake_lines;
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else
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waketime_in_lines = crtc_state->alpm_state.aux_less_wake_lines;
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crtc_state->has_lobf = (crtc_state->set_context_latency + crtc_state->vrr.guardband) >
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(first_sdp_position + waketime_in_lines);
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}
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void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp,
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struct intel_crtc_state *crtc_state,
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struct drm_connector_state *conn_state)
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{
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struct intel_display *display = to_intel_display(intel_dp);
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struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
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int waketime_in_lines, first_sdp_position;
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int context_latency, guardband;
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if (intel_dp->alpm.lobf_disable_debug) {
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drm_dbg_kms(display->drm, "LOBF is disabled by debug flag\n");
···
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if (!intel_alpm_compute_params(intel_dp, crtc_state))
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return;
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-
context_latency = adjusted_mode->crtc_vblank_start - adjusted_mode->crtc_vdisplay;
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guardband = adjusted_mode->crtc_vtotal -
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adjusted_mode->crtc_vdisplay - context_latency;
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first_sdp_position = adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vsync_start;
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if (intel_alpm_aux_less_wake_supported(intel_dp))
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waketime_in_lines = crtc_state->alpm_state.io_wake_lines;
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else
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waketime_in_lines = crtc_state->alpm_state.aux_less_wake_lines;
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-
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crtc_state->has_lobf = (context_latency + guardband) >
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(first_sdp_position + waketime_in_lines);
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crtc_state->has_lobf = true;
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}
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static void lnl_alpm_configure(struct intel_dp *intel_dp,
+3
drivers/gpu/drm/i915/display/intel_alpm.h
+3
drivers/gpu/drm/i915/display/intel_alpm.h
···
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const struct intel_crtc_state *crtc_state);
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void intel_alpm_disable(struct intel_dp *intel_dp);
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bool intel_alpm_get_error(struct intel_dp *intel_dp);
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void intel_alpm_lobf_compute_config_late(struct intel_dp *intel_dp,
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struct intel_crtc_state *crtc_state);
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int intel_alpm_lobf_min_guardband(struct intel_crtc_state *crtc_state);
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#endif
+2
drivers/gpu/drm/i915/display/intel_dp.c
+2
drivers/gpu/drm/i915/display/intel_dp.c
+2
drivers/gpu/drm/i915/display/intel_vrr.c
+2
drivers/gpu/drm/i915/display/intel_vrr.c
···
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#include <drm/drm_print.h>
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#include "intel_alpm.h"
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#include "intel_crtc.h"
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#include "intel_de.h"
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#include "intel_display_regs.h"
···
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if (intel_crtc_has_dp_encoder(crtc_state)) {
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guardband = max(guardband, intel_psr_min_guardband(crtc_state));
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guardband = max(guardband, intel_dp_sdp_min_guardband(crtc_state, true));
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guardband = max(guardband, intel_alpm_lobf_min_guardband(crtc_state));
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}
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return guardband;