[Intel-gfx] [PATCH] drm/i915/dp: Skip the HW readout of DPCD on disabled encoders

From: Imre Deak <imre.deak@intel.com>
To: intel-gfx@lists.freedesktop.org
Cc: "José Roberto de Souza" <jose.souza@intel.com>
Subject: [Intel-gfx] [PATCH] drm/i915/dp: Skip the HW readout of DPCD on disabled encoders
Date: Fri, 15 Oct 2021 15:10:31 +0300	[thread overview]
Message-ID: <20211015121031.870282-1-imre.deak@intel.com> (raw)

Reading out the DP encoders' DPCD during booting or resume is only
required for enabled encoders: such encoders may be modesetted during
the initial commit and the link training this involves depends on an
initialized DPCD. For DDI encoders reading out the DPCD is skipped, do
the same on pre-DDI platforms.

Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 9d8132dd4cc5a..23de500d56b52 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2007,6 +2007,9 @@ void intel_dp_sync_state(struct intel_encoder *encoder,
 {
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
+	if (!crtc_state)
+		return;
+
 	/*
 	 * Don't clobber DPCD if it's been already read out during output
 	 * setup (eDP) or detect.
-- 
2.27.0

