drm/i915/xelpd: Handle PSR2 SDP indication in the prior scanline

In some modes there is not enough time during hblank to transmit PSR2
SDP plus the pixels CRC SDP, if such case happens PSR2 needs to be
disabled.
But eDP spec 1.4b allows to transmit PSR2 SDP in a prior scanline
alone and than later the CRC SDP, allowing PSR2 to be enabled in
those hblank constrained modes.

BSpec: 49274
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210616203158.118111-4-jose.souza@intel.com

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index e508816911fa..3cb8758be404 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -418,6 +418,9 @@ static void intel_psr_enable_sink(struct intel_dp *intel_dp)
 			dpcd_val |= DP_PSR_CRC_VERIFICATION;
 	}
 
+	if (intel_dp->psr.req_psr2_sdp_prior_scanline)
+		dpcd_val |= DP_PSR_SU_REGION_SCANLINE_CAPTURE;
+
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, dpcd_val);
 
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
@@ -585,6 +588,9 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
 		val |= EDP_PSR2_FAST_WAKE(7);
 	}
 
+	if (intel_dp->psr.req_psr2_sdp_prior_scanline)
+		val |= EDP_PSR2_SU_SDP_SCANLINE;
+
 	if (intel_dp->psr.psr2_sel_fetch_enabled) {
 		/* WA 1408330847 */
 		if (IS_TGL_DISPLAY_STEP(dev_priv, STEP_A0, STEP_A0) ||
@@ -814,6 +820,29 @@ static bool psr2_granularity_check(struct intel_dp *intel_dp,
 	return true;
 }
 
+static bool _compute_psr2_sdp_prior_scanline_indication(struct intel_dp *intel_dp,
+							struct intel_crtc_state *crtc_state)
+{
+	const struct drm_display_mode *adjusted_mode = &crtc_state->uapi.adjusted_mode;
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	u32 hblank_total, hblank_ns, req_ns;
+
+	hblank_total = adjusted_mode->crtc_hblank_end - adjusted_mode->crtc_hblank_start;
+	hblank_ns = div_u64(1000000ULL * hblank_total, adjusted_mode->crtc_clock);
+
+	/* From spec: (72 / number of lanes) * 1000 / symbol clock frequency MHz */
+	req_ns = (72 / crtc_state->lane_count) * 1000 / (crtc_state->port_clock / 1000);
+
+	if ((hblank_ns - req_ns) > 100)
+		return true;
+
+	if (DISPLAY_VER(dev_priv) < 13 || intel_dp->edp_dpcd[0] < DP_EDP_14b)
+		return false;
+
+	crtc_state->req_psr2_sdp_prior_scanline = true;
+	return true;
+}
+
 static bool intel_psr2_config_valid(struct intel_dp *intel_dp,
 				    struct intel_crtc_state *crtc_state)
 {
@@ -926,6 +955,12 @@ static bool intel_psr2_config_valid(struct intel_dp *intel_dp,
 		return false;
 	}
 
+	if (!_compute_psr2_sdp_prior_scanline_indication(intel_dp, crtc_state)) {
+		drm_dbg_kms(&dev_priv->drm,
+			    "PSR2 not enabled, PSR2 SDP indication do not fit in hblank\n");
+		return false;
+	}
+
 	tgl_dc3co_exitline_compute_config(intel_dp, crtc_state);
 	return true;
 }
@@ -1173,6 +1208,8 @@ static void intel_psr_enable_locked(struct intel_dp *intel_dp,
 	intel_dp->psr.dc3co_exit_delay = val;
 	intel_dp->psr.dc3co_exitline = crtc_state->dc3co_exitline;
 	intel_dp->psr.psr2_sel_fetch_enabled = crtc_state->enable_psr2_sel_fetch;
+	intel_dp->psr.req_psr2_sdp_prior_scanline =
+		crtc_state->req_psr2_sdp_prior_scanline;
 
 	if (!psr_interrupt_error_check(intel_dp))
 		return;