drm/i915: add PCH DPLL enable/disable functions
With assertions to check transcoder and reference clock state.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 607bd2f..515e0b9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1159,6 +1159,30 @@
}
}
+static void assert_pch_refclk_enabled(struct drm_i915_private *dev_priv)
+{
+ u32 val;
+ bool enabled;
+
+ val = I915_READ(PCH_DREF_CONTROL);
+ enabled = !!(val & (DREF_SSC_SOURCE_MASK | DREF_NONSPREAD_SOURCE_MASK |
+ DREF_SUPERSPREAD_SOURCE_MASK));
+ WARN(!enabled, "PCH refclk assertion failure, should be active but is disabled\n");
+}
+
+static void assert_transcoder_disabled(struct drm_i915_private *dev_priv,
+ enum pipe pipe)
+{
+ int reg;
+ u32 val;
+ bool enabled;
+
+ reg = TRANSCONF(pipe);
+ val = I915_READ(reg);
+ enabled = !!(val & TRANS_ENABLE);
+ WARN(enabled, "transcoder assertion failed, should be off on pipe %c but is still active\n", pipe ? 'B' :'A');
+}
+
/**
* intel_enable_pll - enable a PLL
* @dev_priv: i915 private structure
@@ -1227,6 +1251,54 @@
}
/**
+ * intel_enable_pch_pll - enable PCH PLL
+ * @dev_priv: i915 private structure
+ * @pipe: pipe PLL to enable
+ *
+ * The PCH PLL needs to be enabled before the PCH transcoder, since it
+ * drives the transcoder clock.
+ */
+static void intel_enable_pch_pll(struct drm_i915_private *dev_priv,
+ enum pipe pipe)
+{
+ int reg;
+ u32 val;
+
+ /* PCH only available on ILK+ */
+ BUG_ON(dev_priv->info->gen < 5);
+
+ /* PCH refclock must be enabled first */
+ assert_pch_refclk_enabled(dev_priv);
+
+ reg = PCH_DPLL(pipe);
+ val = I915_READ(reg);
+ val |= DPLL_VCO_ENABLE;
+ I915_WRITE(reg, val);
+ POSTING_READ(reg);
+ udelay(200);
+}
+
+static void intel_disable_pch_pll(struct drm_i915_private *dev_priv,
+ enum pipe pipe)
+{
+ int reg;
+ u32 val;
+
+ /* PCH only available on ILK+ */
+ BUG_ON(dev_priv->info->gen < 5);
+
+ /* Make sure transcoder isn't still depending on us */
+ assert_transcoder_disabled(dev_priv, pipe);
+
+ reg = PCH_DPLL(pipe);
+ val = I915_READ(reg);
+ val &= ~DPLL_VCO_ENABLE;
+ I915_WRITE(reg, val);
+ POSTING_READ(reg);
+ udelay(200);
+}
+
+/**
* intel_enable_pipe - enable a pipe, assertiing requirements
* @dev_priv: i915 private structure
* @pipe: pipe to enable
@@ -2360,14 +2432,7 @@
else
ironlake_fdi_link_train(crtc);
- /* enable PCH DPLL */
- reg = PCH_DPLL(pipe);
- temp = I915_READ(reg);
- if ((temp & DPLL_VCO_ENABLE) == 0) {
- I915_WRITE(reg, temp | DPLL_VCO_ENABLE);
- POSTING_READ(reg);
- udelay(200);
- }
+ intel_enable_pch_pll(dev_priv, pipe);
if (HAS_PCH_CPT(dev)) {
/* Be sure PCH DPLL SEL is set */
@@ -2553,9 +2618,7 @@
}
/* disable PCH DPLL */
- reg = PCH_DPLL(pipe);
- temp = I915_READ(reg);
- I915_WRITE(reg, temp & ~DPLL_VCO_ENABLE);
+ intel_disable_pch_pll(dev_priv, pipe);
/* Switch from PCDclk to Rawclk */
reg = FDI_RX_CTL(pipe);