FAILED: patch "[PATCH] drm/i915: Calculate ironlake intermediate watermarks" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 90c702b88e5b5bbe2be53848aa3aba7c2b64223f Mon Sep 17 00:00:00 2001
From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date: Thu, 19 Oct 2017 17:13:41 +0200
Subject: [PATCH] drm/i915: Calculate ironlake intermediate watermarks
 correctly, v2.
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The watermarks it should calculate against are the old optimal watermarks.
The currently active crtc watermarks are pure fiction, and are invalid in
case of a nonblocking modeset, page flip enabling/disabling planes or any
other reason.

When the crtc is disabled or during a modeset the intermediate watermarks
don't need to be programmed separately, and could be directly assigned
to the optimal watermarks.

Changes since v1:
- Use intel_atomic_get_old_crtc_state. (ville)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019151341.4579-2-maarten.lankhorst@linux.intel.com
[mlankhorst: Add cc stable and bugzilla link, since previous patch doesn't fix issue by itself]
Cc: stable@vger.kernel.org #v4.8+
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102373
(cherry picked from commit b6b178a77210055b153dbc175e4468bd3c7122df)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index c42a65a93b3a..7d2ecabc5de5 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3133,7 +3133,11 @@ static int ilk_compute_intermediate_wm(struct drm_device *dev,
 				       struct intel_crtc_state *newstate)
 {
 	struct intel_pipe_wm *a = &newstate->wm.ilk.intermediate;
-	struct intel_pipe_wm *b = &intel_crtc->wm.active.ilk;
+	struct intel_atomic_state *intel_state =
+		to_intel_atomic_state(newstate->base.state);
+	const struct intel_crtc_state *oldstate =
+		intel_atomic_get_old_crtc_state(intel_state, intel_crtc);
+	const struct intel_pipe_wm *b = &oldstate->wm.ilk.optimal;
 	int level, max_level = ilk_wm_max_level(to_i915(dev));
 
 	/*
@@ -3142,6 +3146,9 @@ static int ilk_compute_intermediate_wm(struct drm_device *dev,
 	 * and after the vblank.
 	 */
 	*a = newstate->wm.ilk.optimal;
+	if (!newstate->base.active || drm_atomic_crtc_needs_modeset(&newstate->base))
+		return 0;
+
 	a->pipe_enabled |= b->pipe_enabled;
 	a->sprites_enabled |= b->sprites_enabled;
 	a->sprites_scaled |= b->sprites_scaled;