From 629154ea4a97810b8571184b17636d1bbb44f81f Mon Sep 17 00:00:00 2001
From: Manasi Navare <manasi.d.navare@intel.com>
Date: Wed, 1 Jul 2020 15:10:52 -0700
Subject: drm/i915/dp: Helper to check for DDI BUF status to get active
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Git-commit: e828da3028b06cba43d4d91b94cb884d8927be09
Patch-mainline: v5.9-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Based on the platform, Bspec expects us to wait or poll with
timeout for DDI BUF IDLE bit to be set to 0 (non idle) or get active
after enabling DDI_BUF_CTL.

v2:
* Based on platform, fixed delay or poll (Ville)
* Use a helper to do this (Imre, Ville)
v3:
* Add a new function _active for DDI BUF CTL to be non idle (Ville)
v4:
* Use the timeout for GLK (Ville)
v5:
* Add bspec quote, change timeout to 500us (Ville)

Cc: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701221052.8946-2-manasi.d.navare@intel.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/display/intel_ddi.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 2120d6da3fcc..5773ebefffc7 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -1195,6 +1195,21 @@ static void intel_wait_ddi_buf_idle(struct drm_i915_private *dev_priv,
 			port_name(port));
 }
 
+static void intel_wait_ddi_buf_active(struct drm_i915_private *dev_priv,
+				      enum port port)
+{
+	/* Wait > 518 usecs for DDI_BUF_CTL to be non idle */
+	if (INTEL_GEN(dev_priv) < 10 && !IS_GEMINILAKE(dev_priv)) {
+		usleep_range(518, 1000);
+		return;
+	}
+
+	if (wait_for_us(!(intel_de_read(dev_priv, DDI_BUF_CTL(port)) &
+			  DDI_BUF_IS_IDLE), 500))
+		drm_err(&dev_priv->drm, "Timeout waiting for DDI BUF %c to get active\n",
+			port_name(port));
+}
+
 static u32 hsw_pll_to_ddi_pll_sel(const struct intel_shared_dpll *pll)
 {
 	switch (pll->info->id) {
@@ -4017,7 +4032,7 @@ static void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp)
 	intel_de_write(dev_priv, DDI_BUF_CTL(port), intel_dp->DP);
 	intel_de_posting_read(dev_priv, DDI_BUF_CTL(port));
 
-	udelay(600);
+	intel_wait_ddi_buf_active(dev_priv, port);
 }
 
 static void intel_ddi_set_link_train(struct intel_dp *intel_dp,
-- 
2.29.2