linux-kernel - [PATCH] Revert "drm/i915: Force state->modeset=true when distrust_bios

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Date:   Wed, 30 Sep 2020 15:47:06 +0200
From:   Stefan Joosten <stefan@...omputing.nl>
To:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] Revert "drm/i915: Force state->modeset=true when
 distrust_bios_wm==true"

The fix of flagging state->modeset whenever distrust_bios_wm is set
causes a regression when initializing display(s) attached to a Lenovo
USB-C docking station. The display remains blank until the dock is
reattached. Revert to bring the behavior of the functional v5.6 stable.

This reverts commit 0f8839f5f323da04a800e6ced1136e4b1e1689a9.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1879442
Signed-off-by: Stefan Joosten <stefan@...omputing.nl>
---
 drivers/gpu/drm/i915/display/intel_display.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index b18c5ac2934d..ece1c28278f7 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -14942,20 +14942,6 @@ static int intel_atomic_check(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
-	/*
-	 * distrust_bios_wm will force a full dbuf recomputation
-	 * but the hardware state will only get updated accordingly
-	 * if state->modeset==true. Hence distrust_bios_wm==true &&
-	 * state->modeset==false is an invalid combination which
-	 * would cause the hardware and software dbuf state to get
-	 * out of sync. We must prevent that.
-	 *
-	 * FIXME clean up this mess and introduce better
-	 * state tracking for dbuf.
-	 */
-	if (dev_priv->wm.distrust_bios_wm)
-		any_ms = true;
-
 	intel_fbc_choose_crtc(dev_priv, state);
 	ret = calc_watermark_data(state);
 	if (ret)
-- 
2.25.4