drm/i915: Initialize PCH refclks at modeset init time

The reference clock configuration must be done before any mode setting
can occur as all outputs must be disabled to change
anything. Initialize the clocks after turning everything off during
the initialization process.

Also, re-initialize the refclk at resume time.
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/i915_drv.c

@@ -471,6 +471,9 @@ static int i915_drm_thaw(struct drm_device *dev)
 		error = i915_gem_init_ringbuffer(dev);
 		mutex_unlock(&dev->struct_mutex);
 
+		if (HAS_PCH_SPLIT(dev))
+			ironlake_init_pch_refclk(dev);
+
 		drm_mode_config_reset(dev);
 		drm_irq_install(dev);
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1302,6 +1302,7 @@ extern int intel_modeset_vga_set_state(struct drm_device *dev, bool state);
 extern bool intel_fbc_enabled(struct drm_device *dev);
 extern void intel_disable_fbc(struct drm_device *dev);
 extern bool ironlake_set_drps(struct drm_device *dev, u8 val);
+extern void ironlake_init_pch_refclk(struct drm_device *dev);
 extern void ironlake_enable_rc6(struct drm_device *dev);
 extern void gen6_set_rps(struct drm_device *dev, u8 val);
 extern void intel_detect_pch (struct drm_device *dev);

drivers/gpu/drm/i915/intel_display.c

@@ -5109,7 +5109,10 @@ static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
 	return ret;
 }
 
-static void ironlake_update_pch_refclk(struct drm_device *dev)
+/*
+ * Initialize reference clocks when the driver loads
+ */
+void ironlake_init_pch_refclk(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_mode_config *mode_config = &dev->mode_config;
@@ -5411,8 +5414,6 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 	ironlake_compute_m_n(intel_crtc->bpp, lane, target_clock, link_bw,
 			     &m_n);
 
-	ironlake_update_pch_refclk(dev);
-
 	fp = clock.n << 16 | clock.m1 << 8 | clock.m2;
 	if (has_reduced_clock)
 		fp2 = reduced_clock.n << 16 | reduced_clock.m1 << 8 |
@@ -7284,6 +7285,9 @@ static void intel_setup_outputs(struct drm_device *dev)
 
 	/* disable all the possible outputs/crtcs before entering KMS mode */
 	drm_helper_disable_unused_functions(dev);
+
+	if (HAS_PCH_SPLIT(dev))
+		ironlake_init_pch_refclk(dev);
 }
 
 static void intel_user_framebuffer_destroy(struct drm_framebuffer *fb)