drm/i915: Update RAWCLK_FREQ register on VLV/CHV

I just noticed that VLV/CHV have a RAWCLK_FREQ register just like PCH
platforms. It lives in the display power well, so we should update it
when enabling the power well.

Interestingly the BIOS seems to leave it at the reset value (125) which
doesn't match the rawclk frequency on VLV/CHV (200 MHz). As always with
these register, the spec is extremely vague what the register does. All
it says is: "This is used to generate a divided down clock for
miscellaneous timers in display." Based on a quick test, at least AUX
and PWM appear to be unaffected by this.

But since the register is there, let's configure it in accordance with
the spec.

Note that we have to move intel_update_rawclk() to occur before we
touch the power wells, so that the dev_priv->rawclk_freq is already
populated when the disp2 enable hook gets called for the first time.
I think this should be safe to do on other platforms as well.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461768202-17544-1-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/i915_dma.c

@@ -454,6 +454,9 @@ static int i915_load_modeset_init(struct drm_device *dev)
 	if (ret)
 		goto cleanup_vga_client;
 
+	/* must happen before intel_power_domains_init_hw() on VLV/CHV */
+	intel_update_rawclk(dev_priv);
+
 	intel_power_domains_init_hw(dev_priv, false);
 
 	intel_csr_ucode_init(dev_priv);

drivers/gpu/drm/i915/i915_reg.h

@@ -2449,6 +2449,8 @@ enum skl_disp_power_wells {
 #define   DPLL_MD_VGA_UDI_MULTIPLIER_MASK	0x0000003f
 #define   DPLL_MD_VGA_UDI_MULTIPLIER_SHIFT	0
 
+#define RAWCLK_FREQ_VLV		_MMIO(VLV_DISPLAY_BASE + 0x6024)
+
 #define _FPA0	0x6040
 #define _FPA1	0x6044
 #define _FPB0	0x6048

drivers/gpu/drm/i915/intel_display.c

@@ -185,6 +185,7 @@ intel_pch_rawclk(struct drm_i915_private *dev_priv)
 static int
 intel_vlv_hrawclk(struct drm_i915_private *dev_priv)
 {
+	/* RAWCLK_FREQ_VLV register updated from power well code */
 	return vlv_get_cck_clock_hpll(dev_priv, "hrawclk",
 				      CCK_DISPLAY_REF_CLOCK_CONTROL);
 }
@@ -218,7 +219,7 @@ intel_g4x_hrawclk(struct drm_i915_private *dev_priv)
 	}
 }
 
-static void intel_update_rawclk(struct drm_i915_private *dev_priv)
+void intel_update_rawclk(struct drm_i915_private *dev_priv)
 {
 	if (HAS_PCH_SPLIT(dev_priv))
 		dev_priv->rawclk_freq = intel_pch_rawclk(dev_priv);
@@ -15455,7 +15456,6 @@ void intel_modeset_init(struct drm_device *dev)
 	}
 
 	intel_update_czclk(dev_priv);
-	intel_update_rawclk(dev_priv);
 	intel_update_cdclk(dev);
 
 	intel_shared_dpll_init(dev);

drivers/gpu/drm/i915/intel_drv.h

@@ -1110,6 +1110,7 @@ void i915_audio_component_init(struct drm_i915_private *dev_priv);
 void i915_audio_component_cleanup(struct drm_i915_private *dev_priv);
 
 /* intel_display.c */
+void intel_update_rawclk(struct drm_i915_private *dev_priv);
 int vlv_get_cck_clock(struct drm_i915_private *dev_priv,
 		      const char *name, u32 reg, int ref_freq);
 extern const struct drm_plane_funcs intel_plane_funcs;

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -948,6 +948,11 @@ static void vlv_init_display_clock_gating(struct drm_i915_private *dev_priv)
 	 */
 	I915_WRITE(MI_ARB_VLV, MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE);
 	I915_WRITE(CBR1_VLV, 0);
+
+	WARN_ON(dev_priv->rawclk_freq == 0);
+
+	I915_WRITE(RAWCLK_FREQ_VLV,
+		   DIV_ROUND_CLOSEST(dev_priv->rawclk_freq, 1000));
 }
 
 static void vlv_display_power_well_init(struct drm_i915_private *dev_priv)