linux-kernel - [PATCH v5 4/4] drm/i915/gen9_bc: Add W/A for missing STRAP config on TGP PCH + CML combos

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Date:   Tue,  9 Feb 2021 16:28:31 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     intel-gfx@...ts.freedesktop.org
Cc:     Matt Roper <matthew.d.roper@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Ville Syrjala <ville.syrjala@...ux.intel.com>,
        Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay@...el.com>,
        Yijun Shen <Yijun.Shen@...l.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Manasi Navare <manasi.d.navare@...el.com>,
        José Roberto de Souza <jose.souza@...el.com>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Dave Airlie <airlied@...hat.com>,
        Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Karthik B S <karthik.b.s@...el.com>,
        dri-devel@...ts.freedesktop.org (open list:DRM DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v5 4/4] drm/i915/gen9_bc: Add W/A for missing STRAP config on TGP PCH + CML combos

Apparently the new gen9_bc platforms that Intel has introduced don't
provide us with a STRAP config register to read from for initializing DDI
B, C, and D detection. So, workaround this by hard-coding our strap config
in intel_setup_outputs().

Changes since v4:
* Split this into it's own commit

Cc: Matt Roper <matthew.d.roper@...el.com>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: Ville Syrjala <ville.syrjala@...ux.intel.com>
[originally from Tejas's work]
Signed-off-by: Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay@...el.com>
Signed-off-by: Lyude Paul <lyude@...hat.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index beed08c00b6c..4dee37f8659d 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -11943,7 +11943,14 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
 
 		/* DDI B, C, D, and F detection is indicated by the SFUSE_STRAP
 		 * register */
-		found = intel_de_read(dev_priv, SFUSE_STRAP);
+		if (HAS_PCH_TGP(dev_priv)) {
+			/* W/A due to lack of STRAP config on TGP PCH*/
+			found = (SFUSE_STRAP_DDIB_DETECTED |
+				 SFUSE_STRAP_DDIC_DETECTED |
+				 SFUSE_STRAP_DDID_DETECTED);
+		} else {
+			found = intel_de_read(dev_priv, SFUSE_STRAP);
+		}
 
 		if (found & SFUSE_STRAP_DDIB_DETECTED)
 			intel_ddi_init(dev_priv, PORT_B);
-- 
2.29.2