[Intel-gfx] [RFC 01/30] drm/i915: rewrite the LCPLL code

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

Right now, we're trying to enable LCPLL at every mode set, but we're
never disabling it. Also, we really don't want to be disabling LCPLL
since it requires a very complex disable sequence. So instead of
enabling it at every mode set, enable it once.

Also, we are currently not checking if the desired values are the ones
we're actually reading/writing, so add some code to check the values
and give us warning messages.

Since the disable/enable sequence is very complex, I am not sure that
the single I915_WRITE we have is enough, but keep it for now to avoid
regressions since everybody's machines seem to be working.

The plan is to add even more code to intel_ddi_pll_init later.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h      |  7 ++++++
 drivers/gpu/drm/i915/intel_ddi.c     | 46 +++++++++++++++++++++++++++++++-----
 drivers/gpu/drm/i915/intel_display.c |  7 ++++++
 drivers/gpu/drm/i915/intel_drv.h     |  1 +
 4 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 4dd9eb8..2eed9d4 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4516,8 +4516,15 @@
 #define LCPLL_CTL			0x130040
 #define  LCPLL_PLL_DISABLE		(1<<31)
 #define  LCPLL_PLL_LOCK			(1<<30)
+#define  LCPLL_CLK_FREQ_MASK		(3<<26)
+#define  LCPLL_CLK_FREQ_450		(0<<26)
+#define  LCPLL_CLK_FREQ_540		(1<<26)
 #define  LCPLL_CD_CLOCK_DISABLE		(1<<25)
 #define  LCPLL_CD2X_CLOCK_DISABLE	(1<<23)
+#define  LCPLL_CD_SOURCE_FCLK		(1<<21)
+
+#define CDCLK_FREQ			0x46200
+#define  CDCLK_FREQ_MASK		0x3FF
 
 /* Pipe WM_LINETIME - watermark line time */
 #define PIPE_WM_LINETIME_A		0x45270
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 170e386..18ebf15 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -682,12 +682,6 @@ void intel_ddi_mode_set(struct drm_encoder *encoder,
 	DRM_DEBUG_KMS("WR PLL: %dKHz refresh rate with p=%d, n2=%d r2=%d\n",
 		      crtc->mode.clock, p, n2, r2);
 
-	/* Enable LCPLL if disabled */
-	temp = I915_READ(LCPLL_CTL);
-	if (temp & LCPLL_PLL_DISABLE)
-		I915_WRITE(LCPLL_CTL,
-				temp & ~LCPLL_PLL_DISABLE);
-
 	/* Configure WR PLL 1, program the correct divider values for
 	 * the desired frequency and wait for warmup */
 	I915_WRITE(WRPLL_CTL1,
@@ -780,3 +774,43 @@ void intel_ddi_dpms(struct drm_encoder *encoder, int mode)
 	I915_WRITE(DDI_BUF_CTL(port),
 			temp);
 }
+
+void intel_ddi_pll_init(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t lcpll_val, clk_val, temp;
+	bool lcpll_needs_change = false;
+
+	/* Check the LCPLL state and fix it if needed. */
+	lcpll_val = I915_READ(LCPLL_CTL);
+	clk_val = I915_READ(CDCLK_FREQ) & CDCLK_FREQ_MASK;
+	DRM_DEBUG_KMS("CDCLK running at %dMHz\n", clk_val + 1);
+
+	temp = lcpll_val & LCPLL_CLK_FREQ_MASK;
+	if ((clk_val == 449 && (temp != LCPLL_CLK_FREQ_450)) ||
+	    (clk_val == 539 && (temp != LCPLL_CLK_FREQ_540))) {
+		DRM_ERROR("LCPLL and CDCLK frequencies don't match\n");
+		lcpll_needs_change = true;
+
+		lcpll_val &= ~LCPLL_CLK_FREQ_MASK;
+		if (clk_val == 449)
+			lcpll_val |= LCPLL_CLK_FREQ_450;
+		else
+			lcpll_val |= LCPLL_CLK_FREQ_540;
+	}
+
+	if (lcpll_val & LCPLL_CD_SOURCE_FCLK) {
+		DRM_ERROR("LCPLL is disabled\n");
+		lcpll_needs_change = true;
+		lcpll_val &= ~LCPLL_PLL_DISABLE;
+	}
+
+	if (lcpll_val & LCPLL_PLL_DISABLE) {
+		DRM_ERROR("LCPLL is disabled\n");
+		lcpll_needs_change = true;
+		lcpll_val &= ~LCPLL_PLL_DISABLE;
+	}
+
+	if (lcpll_needs_change)
+		I915_WRITE(LCPLL_CTL, lcpll_val);
+}
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 42c5758..11687d2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6601,6 +6601,12 @@ static const struct drm_crtc_funcs intel_crtc_funcs = {
 	.page_flip = intel_crtc_page_flip,
 };
 
+static void intel_cpu_pll_init(struct drm_device *dev)
+{
+	if (IS_HASWELL(dev))
+		intel_ddi_pll_init(dev);
+}
+
 static void intel_pch_pll_init(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
@@ -7219,6 +7225,7 @@ void intel_modeset_init(struct drm_device *dev)
 			DRM_DEBUG_KMS("plane %d init failed: %d\n", i, ret);
 	}
 
+	intel_cpu_pll_init(dev);
 	intel_pch_pll_init(dev);
 
 	/* Just disable it once at startup */
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 95f635b..cf9a1ad 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -521,5 +521,6 @@ extern void intel_ddi_dpms(struct drm_encoder *encoder, int mode);
 extern void intel_ddi_mode_set(struct drm_encoder *encoder,
 				struct drm_display_mode *mode,
 				struct drm_display_mode *adjusted_mode);
+extern void intel_ddi_pll_init(struct drm_device *dev);
 
 #endif /* __INTEL_DRV_H__ */
-- 
1.7.11.2