Commit 32c471e8 authored by Ankit Nautiyal's avatar Ankit Nautiyal
Browse files

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: default avatarAnkit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: default avatarMichał Grzelak <michal.grzelak@intel.com>
Reviewed-by: default avatarJouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20260204050250.762718-2-ankit.k.nautiyal@intel.com
parent 58bb6116

drivers/gpu/drm/i915/display/intel_alpm.c

+56 −14
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include "intel_dp_aux.h"

#include "intel_psr.h"

#include "intel_psr_regs.h"

#include "intel_vrr.h"



#define SILENCE_PERIOD_MIN_TIME	80

#define SILENCE_PERIOD_MAX_TIME	180
@@ -248,14 +249,65 @@ bool intel_alpm_compute_params(struct intel_dp *intel_dp, 
	return true;

}



int intel_alpm_lobf_min_guardband(struct intel_crtc_state *crtc_state)

{

	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;

	int first_sdp_position = adjusted_mode->crtc_vtotal -

				 adjusted_mode->crtc_vsync_start;

	int waketime_in_lines;



	/*

	 * #FIXME: Need to check if io_wake_lines or aux_less_wake_lines

	 * is applicable. Currently this information is not readily

	 * available in crtc_state, so max will suffice for now.

	 */

	waketime_in_lines = max(crtc_state->alpm_state.io_wake_lines,

				crtc_state->alpm_state.aux_less_wake_lines);



	if (!crtc_state->has_lobf)

		return 0;



	return first_sdp_position + waketime_in_lines + crtc_state->set_context_latency;

}



void intel_alpm_lobf_compute_config_late(struct intel_dp *intel_dp,

					 struct intel_crtc_state *crtc_state)

{

	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;

	int waketime_in_lines, first_sdp_position;



	if (!crtc_state->has_lobf)

		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

	 * to wake the main link.

	 *

	 * Position of first sdp : vsync_start

	 * start of scl + guardband : vtotal - (scl + guardband)

	 * time in lines to wake main link : waketime_in_lines

	 *

	 * Position of first sdp - start of (scl + guardband) > time in lines to wake main link

	 * vsync_start - (vtotal - (scl + guardband)) > waketime_in_lines

	 * vsync_start - vtotal + scl + guardband > waketime_in_lines

	 * scl + guardband > waketime_in_lines + (vtotal - vsync_start)

	 */

	first_sdp_position = adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vsync_start;

	if (intel_alpm_aux_less_wake_supported(intel_dp))

		waketime_in_lines = crtc_state->alpm_state.io_wake_lines;

	else

		waketime_in_lines = crtc_state->alpm_state.aux_less_wake_lines;



	crtc_state->has_lobf = (crtc_state->set_context_latency + crtc_state->vrr.guardband) >

			       (first_sdp_position + waketime_in_lines);

}



void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp,

				    struct intel_crtc_state *crtc_state,

				    struct drm_connector_state *conn_state)

{

	struct intel_display *display = to_intel_display(intel_dp);

	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;

	int waketime_in_lines, first_sdp_position;

	int context_latency, guardband;



	if (intel_dp->alpm.lobf_disable_debug) {

		drm_dbg_kms(display->drm, "LOBF is disabled by debug flag\n");
@@ -288,17 +340,7 @@ void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp, 
	if (!intel_alpm_compute_params(intel_dp, crtc_state))

		return;



	context_latency = adjusted_mode->crtc_vblank_start - adjusted_mode->crtc_vdisplay;

	guardband = adjusted_mode->crtc_vtotal -

		    adjusted_mode->crtc_vdisplay - context_latency;

	first_sdp_position = adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vsync_start;

	if (intel_alpm_aux_less_wake_supported(intel_dp))

		waketime_in_lines = crtc_state->alpm_state.io_wake_lines;

	else

		waketime_in_lines = crtc_state->alpm_state.aux_less_wake_lines;



	crtc_state->has_lobf = (context_latency + guardband) >

		(first_sdp_position + waketime_in_lines);

	crtc_state->has_lobf = true;

}



static void lnl_alpm_configure(struct intel_dp *intel_dp,

drivers/gpu/drm/i915/display/intel_alpm.h

+3 −0
Original line number Diff line number Diff line
@@ -38,4 +38,7 @@ bool intel_alpm_is_alpm_aux_less(struct intel_dp *intel_dp, 
				 const struct intel_crtc_state *crtc_state);

void intel_alpm_disable(struct intel_dp *intel_dp);

bool intel_alpm_get_error(struct intel_dp *intel_dp);

void intel_alpm_lobf_compute_config_late(struct intel_dp *intel_dp,

					 struct intel_crtc_state *crtc_state);

int intel_alpm_lobf_min_guardband(struct intel_crtc_state *crtc_state);

#endif

drivers/gpu/drm/i915/display/intel_dp.c

+2 −0
Original line number Diff line number Diff line
@@ -7163,6 +7163,8 @@ int intel_dp_compute_config_late(struct intel_encoder *encoder, 
	if (ret)

		return ret;



	intel_alpm_lobf_compute_config_late(intel_dp, crtc_state);



	return 0;

}

drivers/gpu/drm/i915/display/intel_vrr.c

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 


#include <drm/drm_print.h>



#include "intel_alpm.h"

#include "intel_crtc.h"

#include "intel_de.h"

#include "intel_display_regs.h"
@@ -520,6 +521,7 @@ int intel_vrr_compute_optimized_guardband(struct intel_crtc_state *crtc_state) 
	if (intel_crtc_has_dp_encoder(crtc_state)) {

		guardband = max(guardband, intel_psr_min_guardband(crtc_state));

		guardband = max(guardband, intel_dp_sdp_min_guardband(crtc_state, true));

		guardband = max(guardband, intel_alpm_lobf_min_guardband(crtc_state));

	}



	return guardband;