drm/i915/tgl: Enable VD HCP/MFX sub-pipe power gating

HCP/MFX power gating is disabled by default, turn it on for the vd units
available. User space will also issue a MI_FORCE_WAKEUP properly to
wake up proper subwell.

During driver load, init_clock_gating happens after device_info_init_mmio
read the vdbox disable fuse register, so only present vd units will have
these enabled.

BSpec: 14214
HSDES: 1209977827
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Tony Ye <tony.ye@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190823082055.5992-3-lucas.demarchi@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -8615,6 +8615,10 @@ enum {
 #define   GEN9_PWRGT_MEDIA_STATUS_MASK		(1 << 0)
 #define   GEN9_PWRGT_RENDER_STATUS_MASK		(1 << 1)
 
+#define POWERGATE_ENABLE			_MMIO(0xa210)
+#define    VDN_HCP_POWERGATE_ENABLE(n)		BIT(((n) * 2) + 3)
+#define    VDN_MFX_POWERGATE_ENABLE(n)		BIT(((n) * 2) + 4)
+
 #define  GTFIFODBG				_MMIO(0x120000)
 #define    GT_FIFO_SBDEDICATE_FREE_ENTRY_CHV	(0x1f << 20)
 #define    GT_FIFO_FREE_ENTRIES_CHV		(0x7f << 13)

drivers/gpu/drm/i915/intel_pm.c

@@ -9078,6 +9078,22 @@ static void icl_init_clock_gating(struct drm_i915_private *dev_priv)
 		   _MASKED_BIT_ENABLE(GEN11_ENABLE_32_PLANE_MODE));
 }
 
+static void tgl_init_clock_gating(struct drm_i915_private *dev_priv)
+{
+	u32 vd_pg_enable = 0;
+	unsigned int i;
+
+	/* This is not a WA. Enable VD HCP & MFX_ENC powergate */
+	for (i = 0; i < I915_MAX_VCS; i++) {
+		if (HAS_ENGINE(dev_priv, _VCS(i)))
+			vd_pg_enable |= VDN_HCP_POWERGATE_ENABLE(i) |
+					VDN_MFX_POWERGATE_ENABLE(i);
+	}
+
+	I915_WRITE(POWERGATE_ENABLE,
+		   I915_READ(POWERGATE_ENABLE) | vd_pg_enable);
+}
+
 static void cnp_init_clock_gating(struct drm_i915_private *dev_priv)
 {
 	if (!HAS_PCH_CNP(dev_priv))
@@ -9598,7 +9614,7 @@ static void nop_init_clock_gating(struct drm_i915_private *dev_priv)
 void intel_init_clock_gating_hooks(struct drm_i915_private *dev_priv)
 {
 	if (IS_GEN(dev_priv, 12))
-		dev_priv->display.init_clock_gating = nop_init_clock_gating;
+		dev_priv->display.init_clock_gating = tgl_init_clock_gating;
 	else if (IS_GEN(dev_priv, 11))
 		dev_priv->display.init_clock_gating = icl_init_clock_gating;
 	else if (IS_CANNONLAKE(dev_priv))