This is a note to let you know that I've just added the patch titled
drm/i915/bdw: Add missing delay during L3 SQC credit programming
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-bdw-add-missing-delay-during-l3-sqc-credit-programming.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d6a862fe8c48229ba342648bcd535b2404724603 Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@xxxxxxxxx>
Date: Tue, 3 May 2016 15:54:19 +0300
Subject: drm/i915/bdw: Add missing delay during L3 SQC credit programming
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From: Imre Deak <imre.deak@xxxxxxxxx>
commit d6a862fe8c48229ba342648bcd535b2404724603 upstream.
BSpec requires us to wait ~100 clocks before re-enabling clock gating,
so make sure we do this.
CC: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1462280061-1457-2-git-send-email-imre.deak@xxxxxxxxx
(cherry picked from commit 48e5d68d28f00c0cadac5a830980ff3222781abb)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6620,6 +6620,12 @@ static void broadwell_init_clock_gating(
misccpctl = I915_READ(GEN7_MISCCPCTL);
I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
I915_WRITE(GEN8_L3SQCREG1, BDW_WA_L3SQCREG1_DEFAULT);
+ /*
+ * Wait at least 100 clocks before re-enabling clock gating. See
+ * the definition of L3SQCREG1 in BSpec.
+ */
+ POSTING_READ(GEN8_L3SQCREG1);
+ udelay(1);
I915_WRITE(GEN7_MISCCPCTL, misccpctl);
/*
Patches currently in stable-queue which might be from imre.deak@xxxxxxxxx are
queue-4.4/drm-i915-bdw-add-missing-delay-during-l3-sqc-credit-programming.patch
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