linux-kernel - [ 40/68] drm/i915: gen7: implement rczunit workaround

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Date:	Fri, 09 Mar 2012 11:02:54 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Eugeni Dodonov <eugeni.dodonov@...el.com>,
	Kenneth Graunke <kenneth@...tecape.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: [ 40/68] drm/i915: gen7: implement rczunit workaround

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eugeni Dodonov <eugeni.dodonov@...el.com>

commit eae66b50c760233fad526edf4a0d327be17a055d upstream.

This is yet another workaround related to clock gating which we need on
Ivy Bridge.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41353
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44610
Tested-by: Eugeni Dodonov <eugeni.dodonov@...el.com>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@...el.com>
Signed-off-by: Kenneth Graunke <kenneth@...tecape.org>
Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/i915_reg.h      |    1 +
 drivers/gpu/drm/i915/intel_display.c |    5 +++++
 2 files changed, 6 insertions(+)

--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3371,6 +3371,7 @@
 #define  GT_FIFO_FREE_ENTRIES			0x120008
 
 #define GEN6_UCGCTL2				0x9404
+# define GEN6_RCZUNIT_CLOCK_GATE_DISABLE		(1 << 13)
 # define GEN6_RCPBUNIT_CLOCK_GATE_DISABLE		(1 << 12)
 # define GEN6_RCCUNIT_CLOCK_GATE_DISABLE		(1 << 11)
 
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7457,6 +7457,11 @@ static void ivybridge_init_clock_gating(
 	I915_WRITE(WM2_LP_ILK, 0);
 	I915_WRITE(WM1_LP_ILK, 0);
 
+	/* According to the spec, bit 13 (RCZUNIT) must be set on IVB.
+	 * This implements the WaDisableRCZUnitClockGating workaround.
+	 */
+	I915_WRITE(GEN6_UCGCTL2, GEN6_RCZUNIT_CLOCK_GATE_DISABLE);
+
 	I915_WRITE(ILK_DSPCLK_GATE, IVB_VRHUNIT_CLK_GATE);
 
 	for_each_pipe(pipe)


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