drm/i915: fix pnv display core clock readout out

We need the correct clock to accurately assess whether we need to
enable the double wide pipe mode or not.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Stéphane Marchesin <marcheu@chromium.org>
Cc: Stuart Abercrombie <sabercrombie@google.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -61,6 +61,12 @@
 #define   GC_LOW_FREQUENCY_ENABLE	(1 << 7)
 #define   GC_DISPLAY_CLOCK_190_200_MHZ	(0 << 4)
 #define   GC_DISPLAY_CLOCK_333_MHZ	(4 << 4)
+#define   GC_DISPLAY_CLOCK_267_MHZ_PNV	(0 << 4)
+#define   GC_DISPLAY_CLOCK_333_MHZ_PNV	(1 << 4)
+#define   GC_DISPLAY_CLOCK_444_MHZ_PNV	(2 << 4)
+#define   GC_DISPLAY_CLOCK_200_MHZ_PNV	(5 << 4)
+#define   GC_DISPLAY_CLOCK_133_MHZ_PNV	(6 << 4)
+#define   GC_DISPLAY_CLOCK_167_MHZ_PNV	(7 << 4)
 #define   GC_DISPLAY_CLOCK_MASK		(7 << 4)
 #define   GM45_GC_RENDER_CLOCK_MASK	(0xf << 0)
 #define   GM45_GC_RENDER_CLOCK_266_MHZ	(8 << 0)

drivers/gpu/drm/i915/intel_display.c

@@ -4163,6 +4163,30 @@ static int i9xx_misc_get_display_clock_speed(struct drm_device *dev)
 	return 200000;
 }
 
+static int pnv_get_display_clock_speed(struct drm_device *dev)
+{
+	u16 gcfgc = 0;
+
+	pci_read_config_word(dev->pdev, GCFGC, &gcfgc);
+
+	switch (gcfgc & GC_DISPLAY_CLOCK_MASK) {
+	case GC_DISPLAY_CLOCK_267_MHZ_PNV:
+		return 267000;
+	case GC_DISPLAY_CLOCK_333_MHZ_PNV:
+		return 333000;
+	case GC_DISPLAY_CLOCK_444_MHZ_PNV:
+		return 444000;
+	case GC_DISPLAY_CLOCK_200_MHZ_PNV:
+		return 200000;
+	default:
+		DRM_ERROR("Unknown pnv display core clock 0x%04x\n", gcfgc);
+	case GC_DISPLAY_CLOCK_133_MHZ_PNV:
+		return 133000;
+	case GC_DISPLAY_CLOCK_167_MHZ_PNV:
+		return 167000;
+	}
+}
+
 static int i915gm_get_display_clock_speed(struct drm_device *dev)
 {
 	u16 gcfgc = 0;
@@ -9605,9 +9629,12 @@ static void intel_init_display(struct drm_device *dev)
 	else if (IS_I915G(dev))
 		dev_priv->display.get_display_clock_speed =
 			i915_get_display_clock_speed;
-	else if (IS_I945GM(dev) || IS_845G(dev) || IS_PINEVIEW_M(dev))
+	else if (IS_I945GM(dev) || IS_845G(dev))
 		dev_priv->display.get_display_clock_speed =
 			i9xx_misc_get_display_clock_speed;
+	else if (IS_PINEVIEW(dev))
+		dev_priv->display.get_display_clock_speed =
+			pnv_get_display_clock_speed;
 	else if (IS_I915GM(dev))
 		dev_priv->display.get_display_clock_speed =
 			i915gm_get_display_clock_speed;