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

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2026 Intel Corporation
 *
 */

#include <drm/drm_print.h>

#include "intel_de.h"
#include "intel_dip.h"
#include "intel_dip_regs.h"
#include "intel_display_types.h"
#include "intel_hdmi.h"

static int intel_dip_get_as_sdp_transmission_line(const struct intel_crtc_state *crtc_state)
{
	struct intel_display *display = to_intel_display(crtc_state);

	if (!HAS_EMP_AS_SDP_TL(display))
		return 0;

	/*
	 * EMP_AS_SDP_TL defines the T1 position as the default AS SDP
	 * Transmission Line, which corresponds to the start of the
	 * VSYNC pulse.
	 *
	 * Use the T1 position for now.
	 */
	return crtc_state->vrr.vsync_start;
}

u16 intel_dip_read_emp_as_sdp_tl(const struct intel_crtc_state *crtc_state)
{
	struct intel_display *display = to_intel_display(crtc_state);
	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
	u32 val;

	if (!HAS_EMP_AS_SDP_TL(display))
		return 0;

	val = intel_de_read(display, EMP_AS_SDP_TL(display, cpu_transcoder));
	return REG_FIELD_GET(EMP_AS_SDP_DB_TL_MASK, val);
}

void intel_dip_write_emp_as_sdp_tl(const struct intel_crtc_state *crtc_state)
{
	struct intel_display *display = to_intel_display(crtc_state);
	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;

	if (!HAS_EMP_AS_SDP_TL(display))
		return;

	intel_de_write(display,
		       EMP_AS_SDP_TL(display, cpu_transcoder),
		       EMP_AS_SDP_DB_TL(crtc_state->dip.emp_as_sdp_tl));
}

static int intel_dip_sdp_stagger_to_tl(struct intel_crtc_state *crtc_state,
				       int stagger)
{
	return crtc_state->dip.cmn_sdp_tl + stagger;
}

static
void intel_dip_cmn_sdp_tl_compute_config_late(struct intel_crtc_state *crtc_state)
{
	struct intel_display *display = to_intel_display(crtc_state);
	bool as_sdp;

	if (!HAS_COMMON_SDP_TL(display))
		return;

	as_sdp = crtc_state->infoframes.enable &
		 intel_hdmi_infoframe_enable(DP_SDP_ADAPTIVE_SYNC);
	/*
	 * When AS SDP is enabled :
	 *  - The common SDP Transmission Line matches the EMP SDP Transmission Line.
	 *
	 * When AS SDP is disabled:
	 *  - Bspec mentions the positions as lines of delayed vblank.
	 *  - Guardband = 1st line of delayed vblank
	 *  - Common SDP Transmission line is set to 2nd line of delayed vblank.
	 */

	if (as_sdp)
		crtc_state->dip.cmn_sdp_tl = crtc_state->dip.emp_as_sdp_tl;
	else
		crtc_state->dip.cmn_sdp_tl = crtc_state->vrr.guardband - 1;

	if (drm_WARN_ON(display->drm,
			crtc_state->dip.cmn_sdp_tl >=
			crtc_state->vrr.guardband + crtc_state->set_context_latency))
		return;

	/*
	 * Currently we are programming the default stagger values, but these
	 * can be optimized if required, based on number of SDPs enabled.
	 *
	 * Default values of the Transmission lines for SDPs other than AS SDP:
	 * VSC : CMN SDP Transmission line
	 * GMP : CMN SDP Transmission line
	 * PPS : CMN SDP Transmission line + 1
	 * VSC_EXT: CMN SDP Transmission line + 2
	 */
	crtc_state->dip.vsc_sdp_tl = crtc_state->dip.cmn_sdp_tl;
	crtc_state->dip.gmp_sdp_tl =
		intel_dip_sdp_stagger_to_tl(crtc_state, GMP_STAGGER_DEFAULT);
	crtc_state->dip.pps_sdp_tl =
		intel_dip_sdp_stagger_to_tl(crtc_state, PPS_STAGGER_DEFAULT);
	crtc_state->dip.vsc_ext_sdp_tl =
		intel_dip_sdp_stagger_to_tl(crtc_state, VSC_EXT_STAGGER_DEFAULT);
}

void intel_dip_sdp_tl_compute_config_late(struct intel_crtc_state *crtc_state)
{
	crtc_state->dip.emp_as_sdp_tl = intel_dip_get_as_sdp_transmission_line(crtc_state);

	intel_dip_cmn_sdp_tl_compute_config_late(crtc_state);
}

static
void intel_dip_cmn_sdp_transmission_line_get_config(struct intel_crtc_state *crtc_state)
{
	struct intel_display *display = to_intel_display(crtc_state);
	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
	u16 vsc_ext_stagger, pps_stagger, gmp_stagger;
	u32 val;

	if (!HAS_COMMON_SDP_TL(display))
		return;

	val = intel_de_read(display, CMN_SDP_TL(display, cpu_transcoder));

	if (!(val & TRANSMISSION_LINE_ENABLE))
		return;

	crtc_state->dip.cmn_sdp_tl = REG_FIELD_GET(BASE_TRANSMISSION_LINE_MASK, val);

	/* SDP VSC uses same transmission line as CMN base transmission line */
	crtc_state->dip.vsc_sdp_tl = crtc_state->dip.cmn_sdp_tl;

	val = intel_de_read(display, CMN_SDP_TL_STGR_CTL(display, cpu_transcoder));

	vsc_ext_stagger = REG_FIELD_GET(VSC_EXT_STAGGER_MASK, val);
	pps_stagger = REG_FIELD_GET(PPS_STAGGER_MASK, val);
	gmp_stagger = REG_FIELD_GET(GMP_STAGGER_MASK, val);

	crtc_state->dip.vsc_ext_sdp_tl =
		intel_dip_sdp_stagger_to_tl(crtc_state, vsc_ext_stagger);
	crtc_state->dip.pps_sdp_tl =
		intel_dip_sdp_stagger_to_tl(crtc_state, pps_stagger);
	crtc_state->dip.gmp_sdp_tl =
		intel_dip_sdp_stagger_to_tl(crtc_state, gmp_stagger);
}

void intel_dip_sdp_transmission_line_get_config(struct intel_crtc_state *crtc_state)
{
	crtc_state->dip.emp_as_sdp_tl = intel_dip_read_emp_as_sdp_tl(crtc_state);

	intel_dip_cmn_sdp_transmission_line_get_config(crtc_state);
}

static int intel_dip_sdp_tl_to_stagger(const struct intel_crtc_state *crtc_state,
				       u16 sdp_transmission_line)
{
	return sdp_transmission_line - crtc_state->dip.cmn_sdp_tl;
}

void intel_dip_cmn_sdp_transmission_line_enable(const struct intel_crtc_state *crtc_state)
{
	struct intel_display *display = to_intel_display(crtc_state);
	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
	int gmp_stagger;
	int pps_stagger;
	int vsc_ext_stagger;

	if (!HAS_COMMON_SDP_TL(display))
		return;

	gmp_stagger = intel_dip_sdp_tl_to_stagger(crtc_state,
						  crtc_state->dip.gmp_sdp_tl);

	pps_stagger = intel_dip_sdp_tl_to_stagger(crtc_state,
						  crtc_state->dip.pps_sdp_tl);

	vsc_ext_stagger = intel_dip_sdp_tl_to_stagger(crtc_state,
						      crtc_state->dip.vsc_ext_sdp_tl);

	if (drm_WARN_ON(display->drm, gmp_stagger < 0))
		return;
	if (drm_WARN_ON(display->drm, pps_stagger < 0))
		return;
	if (drm_WARN_ON(display->drm, vsc_ext_stagger < 0))
		return;

	intel_de_write(display, CMN_SDP_TL_STGR_CTL(display, cpu_transcoder),
		       GMP_STAGGER(gmp_stagger) |
		       PPS_STAGGER(pps_stagger) |
		       VSC_EXT_STAGGER(vsc_ext_stagger));

	intel_de_write(display, CMN_SDP_TL(display, cpu_transcoder),
		       TRANSMISSION_LINE_ENABLE |
		       BASE_TRANSMISSION_LINE(crtc_state->dip.cmn_sdp_tl));
}

void intel_dip_cmn_sdp_transmission_line_disable(const struct intel_crtc_state *old_crtc_state)
{
	struct intel_display *display = to_intel_display(old_crtc_state);
	enum transcoder cpu_transcoder = old_crtc_state->cpu_transcoder;

	if (!HAS_COMMON_SDP_TL(display))
		return;

	intel_de_write(display, CMN_SDP_TL(display, cpu_transcoder), 0);
}