[4.2.y-ckt stable] Patch "drm/i915: Don't leave old junk in ilk active watermarks on readout" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/i915: Don't leave old junk in ilk active watermarks on readout

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt12.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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>From 20ffa88ca70a62bcbb3bb743b2de98189968b64c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala at linux.intel.com>
Date: Fri, 13 May 2016 17:55:17 +0300
Subject: drm/i915: Don't leave old junk in ilk active watermarks on readout
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commit 7045c3689f148a0c95f42bae8ef3eb2829ac7de9 upstream.

When we read out the watermark state from the hardware we're supposed to
transfer that into the active watermarks, but currently we fail to any
part of the active watermarks that isn't explicitly written. Let's clear
it all upfront.

Looks like this has been like this since the beginning, when I added the
readout. No idea why I didn't clear it up.

Cc: Matt Roper <matthew.d.roper at intel.com>
Fixes: 243e6a44b9ca ("drm/i915: Init HSW watermark tracking in intel_modeset_setup_hw_state()")
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper at intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463151318-14719-2-git-send-email-ville.syrjala@linux.intel.com
(cherry picked from commit 15606534bf0a65d8a74a90fd57b8712d147dbca6)
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 6907a1b..d4b6c20 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3656,6 +3656,8 @@ static void ilk_pipe_wm_get_hw_state(struct drm_crtc *crtc)
 	if (IS_HASWELL(dev) || IS_BROADWELL(dev))
 		hw->wm_linetime[pipe] = I915_READ(PIPE_WM_LINETIME(pipe));

+	memset(active, 0, sizeof(*active));
+
 	active->pipe_enabled = intel_crtc->active;

 	if (active->pipe_enabled) {
--
2.7.4