drm/i915: Rework SAGV block time probing

I'd like to see the SAGV block time we got from the mailbox
in the logs regardless of whether other factors prevent the
use of SAGV.

So let's adjust the code to always query the SAGV block time,
log it, and then reset it if SAGV is not actually supported.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220309164948.10671-3-ville.syrjala@linux.intel.comReviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -3670,8 +3670,8 @@ intel_has_sagv(struct drm_i915_private *dev_priv)
 		dev_priv->sagv_status != I915_SAGV_NOT_CONTROLLED;
 }
 
-static void
-skl_setup_sagv_block_time(struct drm_i915_private *dev_priv)
+static u32
+intel_sagv_block_time(struct drm_i915_private *dev_priv)
 {
 	if (DISPLAY_VER(dev_priv) >= 12) {
 		u32 val = 0;
@@ -3680,23 +3680,30 @@ skl_setup_sagv_block_time(struct drm_i915_private *dev_priv)
 		ret = snb_pcode_read(dev_priv,
 				     GEN12_PCODE_READ_SAGV_BLOCK_TIME_US,
 				     &val, NULL);
-		if (!ret) {
-			dev_priv->sagv_block_time_us = val;
-			return;
+		if (ret) {
+			drm_dbg_kms(&dev_priv->drm, "Couldn't read SAGV block time!\n");
+			return 0;
 		}
 
-		drm_dbg(&dev_priv->drm, "Couldn't read SAGV block time!\n");
+		return val;
 	} else if (DISPLAY_VER(dev_priv) == 11) {
-		dev_priv->sagv_block_time_us = 10;
-		return;
-	} else if (DISPLAY_VER(dev_priv) == 9) {
-		dev_priv->sagv_block_time_us = 30;
-		return;
+		return 10;
+	} else if (DISPLAY_VER(dev_priv) == 9 && !IS_LP(dev_priv)) {
+		return 30;
 	} else {
-		MISSING_CASE(DISPLAY_VER(dev_priv));
+		return 0;
 	}
+}
+
+static void intel_sagv_init(struct drm_i915_private *i915)
+{
+	i915->sagv_block_time_us = intel_sagv_block_time(i915);
 
-	dev_priv->sagv_block_time_us = 0;
+	drm_dbg_kms(&i915->drm, "SAGV supported: %s, original SAGV block time: %u us\n",
+		    str_yes_no(intel_has_sagv(i915)), i915->sagv_block_time_us);
+
+	if (!intel_has_sagv(i915))
+		i915->sagv_block_time_us = 0;
 }
 
 /*
@@ -8175,8 +8182,7 @@ void intel_init_pm(struct drm_i915_private *dev_priv)
 	else if (GRAPHICS_VER(dev_priv) == 5)
 		ilk_get_mem_freq(dev_priv);
 
-	if (intel_has_sagv(dev_priv))
-		skl_setup_sagv_block_time(dev_priv);
+	intel_sagv_init(dev_priv);
 
 	/* For FIFO watermark updates */
 	if (DISPLAY_VER(dev_priv) >= 9) {