[RFC PATCH v3 2/2] drm/i915/display: Synchronize crtc_state for initial commit

[Juasheem Sultan <jdsultan@google.com>]

When attempting the initial commit, there is a mismatch between
the new crtc_state and the old crtc_state. This causes us to fail the
pipe_config comparison and force a modeset. In the case where we are
inheriting an initialized state, we can sync the new and the old state
to pass the comparison and allow us to do a fastset and achieve an
uninterrupted handoff to userspace.

Signed-off-by: Juasheem Sultan <jdsultan@google.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 0d527cf22866..6eef4bd2e251 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -5736,6 +5736,25 @@ static void intel_crtc_check_fastset(const struct intel_crtc_state *old_crtc_sta
 	if (old_crtc_state->vrr.in_range != new_crtc_state->vrr.in_range)
 		new_crtc_state->update_lrr = false;
 
+	/* Copying crtc state if inheriting an old state for commit */
+	if (old_crtc_state->inherited) {
+		new_crtc_state->hw = old_crtc_state->hw;
+
+		new_crtc_state->port_clock = old_crtc_state->port_clock;
+		new_crtc_state->pipe_bpp = old_crtc_state->pipe_bpp;
+		new_crtc_state->cpu_transcoder = old_crtc_state->cpu_transcoder;
+		new_crtc_state->lane_count = old_crtc_state->lane_count;
+		new_crtc_state->output_types = old_crtc_state->output_types;
+		new_crtc_state->dp_m_n = old_crtc_state->dp_m_n;
+		new_crtc_state->framestart_delay = old_crtc_state->framestart_delay;
+		new_crtc_state->pixel_multiplier = old_crtc_state->pixel_multiplier;
+		new_crtc_state->pixel_rate = old_crtc_state->pixel_rate;
+		new_crtc_state->enhanced_framing = old_crtc_state->enhanced_framing;
+		new_crtc_state->dpll_hw_state = old_crtc_state->dpll_hw_state;
+		new_crtc_state->intel_dpll = old_crtc_state->intel_dpll;
+		new_crtc_state->vrr.guardband = old_crtc_state->vrr.guardband;
+	}
+
 	if (!intel_pipe_config_compare(old_crtc_state, new_crtc_state, true)) {
 		drm_dbg_kms(display->drm, "[CRTC:%d:%s] fastset requirement not met, forcing full modeset\n",
 			    crtc->base.base.id, crtc->base.name);
-- 
2.52.0.457.g6b5491de43-goog