[PATCH 3/5] drm/i915: CPT/PPT pch dp transcoder workaround

[Daniel Vetter <daniel.vetter@ffwll.ch>]

We need to set the timing override chicken bit after fdi link training
has completed and before we enable the dp transcoder. We also have to
clear that bit again after disabling the pch dp transcoder.

See "Graphics BSpec: vol4g North Display Engine Registers [IVB],
Display Mode Set Sequence" and "Graphics BSpec: vol4h South Display
Engine Registers [CPT, PPT], South Display Engine Transcoder and FDI
Control, Transcoder Debug and DFT, TRANS_CHICKEN_2" bit 31:

"Workaround : Enable the override prior to enabling the transcoder.
Disable the override after disabling the transcoder."

While at it, use the _PIPE macro for the other TRANS_DP register.

v2: Keep the w/a as-is, but kill the original (but wrongly placed)
workaround introduced in

commit 3bcf603f6d5d18bd9d076dc280de71f48add4101
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Wed Jul 27 11:51:40 2011 -0700

    drm/i915: apply timing generator bug workaround on CPT and PPT

and

commit d4270e57efe9e2536798c59e1ed2fd0a1e5cdfcf
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Tue Oct 11 10:43:02 2011 -0700

    drm/i915: export a CPT mode set verification function

Note that this old code has unconditionally set the w/a, which might
explain why fdi link training sometimes silently fails, and especially
why the auto-train did not seem to work properly.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Paulo Zanoni <przanoni@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_reg.h      |  5 +++--
 drivers/gpu/drm/i915/intel_display.c | 21 +++++++++++++++------
 drivers/gpu/drm/i915/intel_pm.c      |  4 ----
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 2dd880f..f1fe3a0 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3806,7 +3806,8 @@
 #define _TRANSA_CHICKEN2	 0xf0064
 #define _TRANSB_CHICKEN2	 0xf1064
 #define TRANS_CHICKEN2(pipe) _PIPE(pipe, _TRANSA_CHICKEN2, _TRANSB_CHICKEN2)
-#define   TRANS_AUTOTRAIN_GEN_STALL_DIS	(1<<31)
+#define  TRANS_CHICKEN2_TIMING_OVERRIDE		(1<<31)
+
 
 #define SOUTH_CHICKEN1		0xc2000
 #define  FDIA_PHASE_SYNC_SHIFT_OVR	19
@@ -4064,7 +4065,7 @@
 #define TRANS_DP_CTL_A		0xe0300
 #define TRANS_DP_CTL_B		0xe1300
 #define TRANS_DP_CTL_C		0xe2300
-#define TRANS_DP_CTL(pipe)	(TRANS_DP_CTL_A + (pipe) * 0x01000)
+#define TRANS_DP_CTL(pipe)	_PIPE(pipe, TRANS_DP_CTL_A, TRANS_DP_CTL_B)
 #define  TRANS_DP_OUTPUT_ENABLE	(1<<31)
 #define  TRANS_DP_PORT_SEL_B	(0<<29)
 #define  TRANS_DP_PORT_SEL_C	(1<<29)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 129059b..43e1968 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2728,7 +2728,6 @@ static void ironlake_fdi_pll_enable(struct intel_crtc *intel_crtc)
 	int pipe = intel_crtc->pipe;
 	u32 reg, temp;
 
-
 	/* enable PCH FDI RX PLL, wait warmup plus DMI latency */
 	reg = FDI_RX_CTL(pipe);
 	temp = I915_READ(reg);
@@ -3093,6 +3092,14 @@ static void ironlake_pch_enable(struct drm_crtc *crtc)
 	    (intel_pipe_has_type(crtc, INTEL_OUTPUT_DISPLAYPORT) ||
 	     intel_pipe_has_type(crtc, INTEL_OUTPUT_EDP))) {
 		u32 bpc = (I915_READ(PIPECONF(pipe)) & PIPE_BPC_MASK) >> 5;
+
+		/* Workaround: Set the timing override bit before enabling the
+		 * DP pch transcoder. */
+		reg = TRANS_CHICKEN2(pipe);
+		temp = I915_READ(reg);
+		temp |= TRANS_CHICKEN2_TIMING_OVERRIDE;
+		I915_WRITE(reg, temp);
+
 		reg = TRANS_DP_CTL(pipe);
 		temp = I915_READ(reg);
 		temp &= ~(TRANS_DP_PORT_SEL_MASK |
@@ -3217,16 +3224,12 @@ prepare: /* separate function? */
 void intel_cpt_verify_modeset(struct drm_device *dev, int pipe)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int dslreg = PIPEDSL(pipe), tc2reg = TRANS_CHICKEN2(pipe);
+	int dslreg = PIPEDSL(pipe);
 	u32 temp;
 
 	temp = I915_READ(dslreg);
 	udelay(500);
 	if (wait_for(I915_READ(dslreg) != temp, 5)) {
-		/* Without this, mode sets may fail silently on FDI */
-		I915_WRITE(tc2reg, TRANS_AUTOTRAIN_GEN_STALL_DIS);
-		udelay(250);
-		I915_WRITE(tc2reg, 0);
 		if (wait_for(I915_READ(dslreg) != temp, 5))
 			DRM_ERROR("mode set failed: pipe %d stuck\n", pipe);
 	}
@@ -3460,6 +3463,12 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 			BUG(); /* wtf */
 		}
 		I915_WRITE(PCH_DPLL_SEL, temp);
+
+		/* Workaround: Clear the timing override chicken bit again. */
+		reg = TRANS_CHICKEN2(pipe);
+		temp = I915_READ(reg);
+		temp &= ~TRANS_CHICKEN2_TIMING_OVERRIDE;
+		I915_WRITE(reg, temp);
 	}
 
 	/* disable PCH DPLL */
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index a04b336..3469fbd 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3786,7 +3786,6 @@ static void ibx_init_clock_gating(struct drm_device *dev)
 static void cpt_init_clock_gating(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int pipe;
 
 	/*
 	 * On Ibex Peak and Cougar Point, we need to disable clock
@@ -3796,9 +3795,6 @@ static void cpt_init_clock_gating(struct drm_device *dev)
 	I915_WRITE(SOUTH_DSPCLK_GATE_D, PCH_DPLSUNIT_CLOCK_GATE_DISABLE);
 	I915_WRITE(SOUTH_CHICKEN2, I915_READ(SOUTH_CHICKEN2) |
 		   DPLS_EDP_PPS_FIX_DIS);
-	/* Without this, mode sets may fail silently on FDI */
-	for_each_pipe(pipe)
-		I915_WRITE(TRANS_CHICKEN2(pipe), TRANS_AUTOTRAIN_GEN_STALL_DIS);
 }
 
 void intel_init_clock_gating(struct drm_device *dev)
-- 
1.7.11.4