linux-kernel - [PATCH v2 3/4] drm/i915/dp: Use the generic helper to control LTTPR transparent mode

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Message-Id: <20241211-drm-dp-msm-add-lttpr-transparent-mode-set-v2-3-d5906ed38b28@linaro.org>
Date: Wed, 11 Dec 2024 15:04:14 +0200
From: Abel Vesa <abel.vesa@...aro.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>, 
 Danilo Krummrich <dakr@...hat.com>, 
 Jani Nikula <jani.nikula@...ux.intel.com>, 
 Rodrigo Vivi <rodrigo.vivi@...el.com>, 
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, 
 Tvrtko Ursulin <tursulin@...ulin.net>, Rob Clark <robdclark@...il.com>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Sean Paul <sean@...rly.run>, 
 Marijn Suijten <marijn.suijten@...ainline.org>
Cc: Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, Johan Hovold <johan@...nel.org>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 nouveau@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org, 
 intel-xe@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org, 
 freedreno@...ts.freedesktop.org, Abel Vesa <abel.vesa@...aro.org>
Subject: [PATCH v2 3/4] drm/i915/dp: Use the generic helper to control
 LTTPR transparent mode

LTTPRs operating modes are defined by the DisplayPort standard and the
generic framework now provides a helper to switch between them, which
is handling the explicit disabling of non-transparent mode and its
disable->enable sequence mentioned in the DP Standard v2.0 section
3.6.6.1.

So use the new drm generic helper instead as it makes the code a bit
cleaner.

Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
---
 .../gpu/drm/i915/display/intel_dp_link_training.c  | 24 +++++-----------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index ea9b4730a176f16af56810248d1b66b9d97c5fd0..6982e6e9bcc8ab5f689ba1b02df334aa352a430c 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -118,9 +118,6 @@ intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable)
 	u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
 			  DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
 
-	if (drm_dp_dpcd_write(&intel_dp->aux, DP_PHY_REPEATER_MODE, &val, 1) != 1)
-		return false;
-
 	intel_dp->lttpr_common_caps[DP_PHY_REPEATER_MODE -
 				    DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV] = val;
 
@@ -145,6 +142,7 @@ static bool intel_dp_lttpr_transparent_mode_enabled(struct intel_dp *intel_dp)
 static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 {
 	int lttpr_count;
+	int ret;
 
 	if (!intel_dp_read_lttpr_common_caps(intel_dp, dpcd))
 		return 0;
@@ -171,22 +169,8 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
 		return lttpr_count;
 	}
 
-	/*
-	 * See DP Standard v2.0 3.6.6.1. about the explicit disabling of
-	 * non-transparent mode and the disable->enable non-transparent mode
-	 * sequence.
-	 */
-	intel_dp_set_lttpr_transparent_mode(intel_dp, true);
-
-	/*
-	 * In case of unsupported number of LTTPRs or failing to switch to
-	 * non-transparent mode fall-back to transparent link training mode,
-	 * still taking into account any LTTPR common lane- rate/count limits.
-	 */
-	if (lttpr_count < 0)
-		goto out_reset_lttpr_count;
-
-	if (!intel_dp_set_lttpr_transparent_mode(intel_dp, false)) {
+	ret = drm_dp_lttpr_init(&intel_dp->aux, lttpr_count));
+	if (ret) {
 		lt_dbg(intel_dp, DP_PHY_DPRX,
 		       "Switching to LTTPR non-transparent LT mode failed, fall-back to transparent mode\n");
 
@@ -195,6 +179,8 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
 		goto out_reset_lttpr_count;
 	}
 
+	intel_dp_set_lttpr_transparent_mode(intel_dp, false);
+
 	return lttpr_count;
 
 out_reset_lttpr_count:

-- 
2.34.1