On Tue, 2026-09-15 at 23:34 +0530, Animesh Manna wrote:
> For DP2.1, ALPM (Advanced Link Power Management) is optional: Panel
> Replay can be supported without ALPM. Until now ALPM enablement was
> derived implicitly from other features - eDP Panel Replay and PSR2
> always implied ALPM (intel_psr_needs_alpm()), while LOBF was tracked
> separately via has_lobf - so this scattered, feature-coupled logic
> cannot express "Panel Replay without ALPM".
>
> Introduce a single crtc_state->has_alpm flag as the source of truth
> for
> whether ALPM is enabled for a pipe configuration, computed during
> config
> validation:
>
> - Panel Replay: from alpm_config_valid() when ALPM is possible; eDP
> Panel Replay additionally requires has_alpm.
> - PSR2 / Selective Update: from intel_alpm_is_possible().
> - LOBF: from has_lobf.
>
> The Panel Replay path sets has_alpm speculatively, so clear it when
> Panel Replay is not the finally selected feature, ensuring a PSR1
> fallback never enables ALPM.
>
> Use has_alpm in place of the feature-specific checks in the ALPM
> configure, port configure, sink enable and MAC-transmit-LFPS paths,
> and
> key the late wake-line selection off has_alpm / has_panel_replay.
>
> Also rename intel_alpm_is_alpm_aux_less() to intel_alpm_is_aux_less()
> and base the aux-less decision on has_panel_replay, keeping the
> source
> programming consistent with the sink's DP_ALPM_MODE_AUX_LESS. The now
> unused intel_psr_needs_alpm() is removed.
>
> Cc: Jouni Högander <[email protected]>
> Signed-off-by: Animesh Manna <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_alpm.c | 25 +++++-----
> drivers/gpu/drm/i915/display/intel_alpm.h | 4 +-
> drivers/gpu/drm/i915/display/intel_cx0_phy.c | 6 ++-
> .../drm/i915/display/intel_display_types.h | 1 +
> drivers/gpu/drm/i915/display/intel_lt_phy.c | 2 +-
> drivers/gpu/drm/i915/display/intel_psr.c | 48 +++++++++++------
> --
> drivers/gpu/drm/i915/display/intel_psr.h | 1 -
> 7 files changed, 47 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 29a93a252fe9..236341aa3c8d 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -37,11 +37,11 @@ bool intel_alpm_aux_less_wake_supported(struct
> intel_dp *intel_dp)
> return intel_dp->alpm_dpcd & DP_ALPM_AUX_LESS_CAP;
> }
>
> -bool intel_alpm_is_alpm_aux_less(struct intel_dp *intel_dp,
> - const struct intel_crtc_state
> *crtc_state)
> +bool intel_alpm_is_aux_less(struct intel_dp *intel_dp,
> + const struct intel_crtc_state
> *crtc_state)
> {
> - return intel_psr_needs_alpm_aux_less(intel_dp, crtc_state)
> ||
> - (crtc_state->has_lobf &&
> intel_alpm_aux_less_wake_supported(intel_dp));
> + return crtc_state->has_panel_replay ||
> + (crtc_state->has_lobf &&
> intel_alpm_aux_less_wake_supported(intel_dp));
> }
>
> bool intel_alpm_source_supported(struct intel_connector *connector)
> @@ -537,6 +537,7 @@ void intel_alpm_lobf_compute_config_late(struct
> intel_dp *intel_dp,
>
> crtc_state->has_lobf = (crtc_state->set_context_latency +
> crtc_state->vrr.guardband) >
> (first_sdp_position +
> waketime_in_lines);
> + crtc_state->has_alpm = crtc_state->has_lobf;
> }
>
> void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp,
> @@ -719,7 +720,7 @@ void intel_alpm_pr_as_sdp_update(const struct
> intel_crtc_state *crtc_state)
> intel_dp = enc_to_intel_dp(encoder);
>
> if (!intel_dp->as_sdp_supported ||
> - !intel_alpm_is_alpm_aux_less(intel_dp,
> crtc_state))
> + !intel_alpm_is_aux_less(intel_dp, crtc_state))
> continue;
>
> mutex_lock(&intel_dp->alpm.lock);
> @@ -735,8 +736,7 @@ static void lnl_alpm_configure(struct intel_dp
> *intel_dp,
> enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> u32 alpm_ctl, alpm_ctl2, lttpr_count;
>
> - if (DISPLAY_VER(display) < 20 ||
> (!intel_psr_needs_alpm(intel_dp, crtc_state) &&
> - !crtc_state->has_lobf))
> + if (DISPLAY_VER(display) < 20 || !crtc_state->has_alpm)
> return;
>
> mutex_lock(&intel_dp->alpm.lock);
> @@ -744,7 +744,7 @@ static void lnl_alpm_configure(struct intel_dp
> *intel_dp,
> * Panel Replay on eDP is always using ALPM aux less. I.e.
> no need to
> * check panel support at this point.
> */
> - if (intel_alpm_is_alpm_aux_less(intel_dp, crtc_state)) {
> + if (intel_alpm_is_aux_less(intel_dp, crtc_state)) {
> alpm_ctl = ALPM_CTL_ALPM_ENABLE |
> ALPM_CTL_ALPM_AUX_LESS_ENABLE |
> ALPM_CTL_AUX_LESS_SLEEP_HOLD_TIME_50_SYMBOLS
> ;
> @@ -792,10 +792,10 @@ void intel_alpm_port_configure(struct intel_dp
> *intel_dp,
> enum port port = dp_to_dig_port(intel_dp)->base.port;
> u32 alpm_ctl_val = 0, lfps_ctl_val = 0;
>
> - if (DISPLAY_VER(display) < 20)
> + if (DISPLAY_VER(display) < 20 || !crtc_state->has_alpm)
> return;
>
> - if (intel_alpm_is_alpm_aux_less(intel_dp, crtc_state)) {
> + if (intel_alpm_is_aux_less(intel_dp, crtc_state)) {
> int lfps_cycle = get_lfps_cycle_count(crtc_state);
> u32 lfps_cycle_val;
>
> @@ -854,13 +854,12 @@ void intel_alpm_enable_sink(struct intel_dp
> *intel_dp,
> {
> u8 val;
>
> - if (!intel_psr_needs_alpm(intel_dp, crtc_state) &&
> !crtc_state->has_lobf)
> + if (!crtc_state->has_alpm)
> return;
>
> val = DP_ALPM_ENABLE | DP_ALPM_LOCK_ERROR_IRQ_HPD_ENABLE;
>
> - if (crtc_state->has_panel_replay || (crtc_state->has_lobf &&
> -
> intel_alpm_aux_less_wake_supported(intel_dp)))
> + if (intel_alpm_is_aux_less(intel_dp, crtc_state))
> val |= DP_ALPM_MODE_AUX_LESS;
>
> drm_dp_dpcd_writeb(&intel_dp->aux, DP_RECEIVER_ALPM_CONFIG,
> val);
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.h
> b/drivers/gpu/drm/i915/display/intel_alpm.h
> index ea90eba76ca7..5d404e7b07de 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.h
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.h
> @@ -35,8 +35,8 @@ void intel_alpm_lobf_enable(const struct
> intel_crtc_state *new_crtc_state);
> void intel_alpm_lobf_debugfs_add(struct intel_connector *connector);
> bool intel_alpm_aux_wake_supported(struct intel_dp *intel_dp);
> bool intel_alpm_aux_less_wake_supported(struct intel_dp *intel_dp);
> -bool intel_alpm_is_alpm_aux_less(struct intel_dp *intel_dp,
> - const struct intel_crtc_state
> *crtc_state);
> +bool intel_alpm_is_aux_less(struct intel_dp *intel_dp,
> + const struct intel_crtc_state
> *crtc_state);
> bool intel_alpm_pr_as_sdp_skip_frames_enabled(struct intel_dp
> *intel_dp,
> const struct
> intel_crtc_state *crtc_state);
> void intel_alpm_pr_as_sdp_update(const struct intel_crtc_state
> *crtc_state);
> diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> index dbebd7210848..26a5d40289ac 100644
> --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> @@ -3449,8 +3449,10 @@ void intel_lnl_mac_transmit_lfps(struct
> intel_encoder *encoder,
> int i;
> u8 owned_lane_mask;
>
> - if (DISPLAY_VER(display) < 20 ||
> - !intel_alpm_is_alpm_aux_less(enc_to_intel_dp(encoder),
> crtc_state))
> + if (DISPLAY_VER(display) < 20 || !crtc_state->has_alpm)
> + return;
> +
> + if (!intel_alpm_is_aux_less(enc_to_intel_dp(encoder),
> crtc_state))
> return;
>
> owned_lane_mask = intel_cx0_get_owned_lane_mask(encoder);
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> b/drivers/gpu/drm/i915/display/intel_display_types.h
> index a5f18ac8a7d0..e2cc73c98479 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1448,6 +1448,7 @@ struct intel_crtc_state {
> u8 silence_period_sym_clocks;
> u8 lfps_half_cycle_num_of_syms;
> } alpm_state;
> + bool has_alpm;
>
> /* to track changes in plane color blocks */
> bool plane_color_changed;
> diff --git a/drivers/gpu/drm/i915/display/intel_lt_phy.c
> b/drivers/gpu/drm/i915/display/intel_lt_phy.c
> index 4fe010df20be..8ebbdc3c0184 100644
> --- a/drivers/gpu/drm/i915/display/intel_lt_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_lt_phy.c
> @@ -2371,7 +2371,7 @@ void intel_xe3plpd_mac_transmit_lfps(struct
> intel_encoder *encoder,
> struct ref_tracker *wakeref;
> u8 owned_lane_mask;
>
> - if (!intel_alpm_is_alpm_aux_less(intel_dp, crtc_state))
> + if (!crtc_state->has_alpm ||
> !intel_alpm_is_aux_less(intel_dp, crtc_state))
> return;
>
> wakeref = intel_lt_phy_transaction_begin(encoder);
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index 872e253db178..1f14dbe57512 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1648,6 +1648,8 @@ static bool
> intel_sel_update_config_valid(struct intel_crtc_state *crtc_state,
> crtc_state->enable_psr2_su_region_et =
> psr2_su_region_et_valid(connector,
>
> crtc_state->has_panel_replay);
>
> + crtc_state->has_alpm = intel_alpm_is_possible(intel_dp);
For PSR2 right place for this is in intel_psr2_config_valid. There is
already alpm_config_valid call.
I would rather set it in one place. At the end of
intel_psr_compute_config_late if doing it this way.
I would rather target to have :
1. alpm_compute_config ()
doing intel_alpm_compute_params. Setting two new flags in
alpm_state->aux_less_possible and alpm_state->aux_wake_possible. Also
doing what lobf_compute_config is doing now.
2. psr_compute_config
using values/flags computed by alpm_compute_config and choosing
psr/psr2/pr based on those.
...
3. psr_compute_config_late
no changes.
4. alpm_compute_config_late
set has_lobf and has_alpm based on calculation by
alpm_compute_config, psr_compute_config and psr_compute_config_late.
Next logical move after this would be to have the configuration of ALPM
happening in one place. Not needed in this patch set though.
BR,
Jouni Högander
> +
> return true;
>
> unsupported:
> @@ -1735,11 +1737,17 @@ static bool
> _panel_replay_compute_config(struct intel_crtc_state *crtc_state,
> crtc_state->link_off_after_as_sdp_when_pr_active =
> compute_link_off_after_as_sdp_when_pr_active(connector);
> crtc_state->disable_as_sdp_when_pr_active =
> compute_disable_as_sdp_when_pr_active(connector);
>
> + if (intel_alpm_is_possible(intel_dp))
> + crtc_state->has_alpm = alpm_config_valid(intel_dp,
> crtc_state, true, true, false);
> +
> if (!intel_dp_is_edp(intel_dp))
> return true;
>
> /* Remaining checks are for eDP only */
>
> + if (!crtc_state->has_alpm)
> + return false;
> +
> if (to_intel_crtc(crtc_state->uapi.crtc)->pipe != PIPE_A &&
> to_intel_crtc(crtc_state->uapi.crtc)->pipe != PIPE_B)
> return false;
> @@ -1762,9 +1770,6 @@ static bool _panel_replay_compute_config(struct
> intel_crtc_state *crtc_state,
> return false;
> }
>
> - if (!alpm_config_valid(intel_dp, crtc_state, true, true,
> false))
> - return false;
> -
> return true;
> }
>
> @@ -1888,6 +1893,15 @@ void intel_psr_compute_config(struct intel_dp
> *intel_dp,
> crtc_state->panel_replay_dsc_support = connector-
> >dp.panel_replay_caps.dsc_support;
> crtc_state->has_panel_replay =
> _panel_replay_compute_config(crtc_state, conn_state);
>
> + /*
> + * has_alpm may have been set speculatively while evaluating
> Panel
> + * Replay. It is only valid if Panel Replay was actually
> selected;
> + * otherwise the finally chosen feature (PSR2/SU or LOBF)
> decides it and
> + * a PSR1 fallback must not enable ALPM.
> + */
> + if (!crtc_state->has_panel_replay)
> + crtc_state->has_alpm = false;
> +
> crtc_state->has_psr = crtc_state->has_panel_replay ? true :
> _psr_compute_config(intel_dp, crtc_state,
> conn_state);
>
> @@ -4555,16 +4569,6 @@ void intel_psr_connector_debugfs_add(struct
> intel_connector *connector)
> connector,
> &i915_psr_status_fops);
> }
>
> -bool intel_psr_needs_alpm(struct intel_dp *intel_dp, const struct
> intel_crtc_state *crtc_state)
> -{
> - /*
> - * eDP Panel Replay uses always ALPM
> - * PSR2 uses ALPM but PSR1 doesn't
> - */
> - return intel_dp_is_edp(intel_dp) && (crtc_state-
> >has_sel_update ||
> - crtc_state-
> >has_panel_replay);
> -}
> -
> bool intel_psr_needs_alpm_aux_less(struct intel_dp *intel_dp,
> const struct intel_crtc_state
> *crtc_state)
> {
> @@ -4578,15 +4582,17 @@ void intel_psr_compute_config_late(struct
> intel_dp *intel_dp,
> int vblank = intel_crtc_vblank_length(crtc_state);
> int wake_lines;
>
> - if (intel_psr_needs_alpm_aux_less(intel_dp, crtc_state))
> - wake_lines = crtc_state-
> >alpm_state.aux_less_wake_lines;
> - else if (intel_psr_needs_alpm(intel_dp, crtc_state))
> - wake_lines = DISPLAY_VER(display) < 20 ?
> - psr2_block_count_lines(crtc_state-
> >alpm_state.io_wake_lines,
> - crtc_state-
> >alpm_state.fast_wake_lines) :
> - crtc_state->alpm_state.io_wake_lines;
> - else
> + if (crtc_state->has_alpm) {
> + if (crtc_state->has_panel_replay)
> + wake_lines = crtc_state-
> >alpm_state.aux_less_wake_lines;
> + else
> + wake_lines = DISPLAY_VER(display) < 20 ?
> +
> psr2_block_count_lines(crtc_state->alpm_state.io_wake_lines,
> +
> crtc_state->alpm_state.fast_wake_lines) :
> + crtc_state-
> >alpm_state.io_wake_lines;
> + } else {
> wake_lines = 0;
> + }
>
> /*
> * Disable the PSR features if wake lines exceed the
> available vblank.
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.h
> b/drivers/gpu/drm/i915/display/intel_psr.h
> index d545fdaa0de7..4905ba4da4b8 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.h
> +++ b/drivers/gpu/drm/i915/display/intel_psr.h
> @@ -79,7 +79,6 @@ void intel_psr_trigger_frame_change_event(struct
> intel_dsb *dsb,
> int intel_psr_min_set_context_latency(const struct intel_crtc_state
> *crtc_state);
> void intel_psr_connector_debugfs_add(struct intel_connector
> *connector);
> void intel_psr_debugfs_register(struct intel_display *display);
> -bool intel_psr_needs_alpm(struct intel_dp *intel_dp, const struct
> intel_crtc_state *crtc_state);
> bool intel_psr_needs_alpm_aux_less(struct intel_dp *intel_dp,
> const struct intel_crtc_state
> *crtc_state);
> void intel_psr_compute_config_late(struct intel_dp *intel_dp,
