drm/i915/adl_p: CDCLK crawl support for ADL

CDCLK crawl feature allows to change CDCLK frequency
without disabling the actual PLL and doesn't require
a full modeset.

v2: - Added has_cdclk_crawl as a feature flag to
      intel_device_info(Matt Roper)
    - s/gen13_cdclk_pll_crawl/adlp_cdclk_pll_crawl/
      (Matt Roper)

Cc: Mika Kahola <[email protected]>
Reviewed-by: Mika Kahola <[email protected]>
Signed-off-by: Stanislav Lisovskiy <[email protected]>
Signed-off-by: Gwan-gyeong Mun <[email protected]>
Signed-off-by: Jani Nikula <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: StanFox1984

drivers/gpu/drm/i915/display/intel_cdclk.c

@@ -1548,6 +1548,35 @@ static void cnl_cdclk_pll_enable(struct drm_i915_private *dev_priv, int vco)
 	dev_priv->cdclk.hw.vco = vco;
 }
 
+static bool has_cdclk_crawl(struct drm_i915_private *i915)
+{
+	return INTEL_INFO(i915)->has_cdclk_crawl;
+}
+
+static void adlp_cdclk_pll_crawl(struct drm_i915_private *dev_priv, int vco)
+{
+	int ratio = DIV_ROUND_CLOSEST(vco, dev_priv->cdclk.hw.ref);
+	u32 val;
+
+	/* Write PLL ratio without disabling */
+	val = CNL_CDCLK_PLL_RATIO(ratio) | BXT_DE_PLL_PLL_ENABLE;
+	intel_de_write(dev_priv, BXT_DE_PLL_ENABLE, val);
+
+	/* Submit freq change request */
+	val |= BXT_DE_PLL_FREQ_REQ;
+	intel_de_write(dev_priv, BXT_DE_PLL_ENABLE, val);
+
+	/* Timeout 200us */
+	if (intel_de_wait_for_set(dev_priv, BXT_DE_PLL_ENABLE,
+				  BXT_DE_PLL_LOCK | BXT_DE_PLL_FREQ_REQ_ACK, 1))
+		DRM_ERROR("timeout waiting for FREQ change request ack\n");
+
+	val &= ~BXT_DE_PLL_FREQ_REQ;
+	intel_de_write(dev_priv, BXT_DE_PLL_ENABLE, val);
+
+	dev_priv->cdclk.hw.vco = vco;
+}
+
 static u32 bxt_cdclk_cd2x_pipe(struct drm_i915_private *dev_priv, enum pipe pipe)
 {
 	if (DISPLAY_VER(dev_priv) >= 12) {
@@ -1620,14 +1649,16 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
 		return;
 	}
 
-	if (DISPLAY_VER(dev_priv) >= 11 || IS_CANNONLAKE(dev_priv)) {
+	if (has_cdclk_crawl(dev_priv) && dev_priv->cdclk.hw.vco > 0 && vco > 0) {
+		if (dev_priv->cdclk.hw.vco != vco)
+			adlp_cdclk_pll_crawl(dev_priv, vco);
+	} else if (DISPLAY_VER(dev_priv) >= 11 || IS_CANNONLAKE(dev_priv)) {
 		if (dev_priv->cdclk.hw.vco != 0 &&
 		    dev_priv->cdclk.hw.vco != vco)
 			cnl_cdclk_pll_disable(dev_priv);
 
 		if (dev_priv->cdclk.hw.vco != vco)
 			cnl_cdclk_pll_enable(dev_priv, vco);
-
 	} else {
 		if (dev_priv->cdclk.hw.vco != 0 &&
 		    dev_priv->cdclk.hw.vco != vco)
@@ -1820,6 +1851,28 @@ void intel_cdclk_uninit_hw(struct drm_i915_private *i915)
 		skl_cdclk_uninit_hw(i915);
 }
 
+static bool intel_cdclk_can_crawl(struct drm_i915_private *dev_priv,
+				  const struct intel_cdclk_config *a,
+				  const struct intel_cdclk_config *b)
+{
+	int a_div, b_div;
+
+	if (!has_cdclk_crawl(dev_priv))
+		return false;
+
+	/*
+	 * The vco and cd2x divider will change independently
+	 * from each, so we disallow cd2x change when crawling.
+	 */
+	a_div = DIV_ROUND_CLOSEST(a->vco, a->cdclk);
+	b_div = DIV_ROUND_CLOSEST(b->vco, b->cdclk);
+
+	return a->vco != 0 && b->vco != 0 &&
+		a->vco != b->vco &&
+		a_div == b_div &&
+		a->ref == b->ref;
+}
+
 /**
  * intel_cdclk_needs_modeset - Determine if changong between the CDCLK
  *                             configurations requires a modeset on all pipes
@@ -2475,7 +2528,7 @@ int intel_modeset_calc_cdclk(struct intel_atomic_state *state)
 	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
 	const struct intel_cdclk_state *old_cdclk_state;
 	struct intel_cdclk_state *new_cdclk_state;
-	enum pipe pipe;
+	enum pipe pipe = INVALID_PIPE;
 	int ret;
 
 	new_cdclk_state = intel_atomic_get_cdclk_state(state);
@@ -2527,15 +2580,18 @@ int intel_modeset_calc_cdclk(struct intel_atomic_state *state)
 
 		if (drm_atomic_crtc_needs_modeset(&crtc_state->uapi))
 			pipe = INVALID_PIPE;
-	} else {
-		pipe = INVALID_PIPE;
 	}
 
-	if (pipe != INVALID_PIPE) {
+	if (intel_cdclk_can_crawl(dev_priv,
+				  &old_cdclk_state->actual,
+				  &new_cdclk_state->actual)) {
+		drm_dbg_kms(&dev_priv->drm,
+			    "Can change cdclk via crawl\n");
+	} else if (pipe != INVALID_PIPE) {
 		new_cdclk_state->pipe = pipe;
 
 		drm_dbg_kms(&dev_priv->drm,
-			    "Can change cdclk with pipe %c active\n",
+			    "Can change cdclk cd2x divider with pipe %c active\n",
 			    pipe_name(pipe));
 	} else if (intel_cdclk_needs_modeset(&old_cdclk_state->actual,
 					     &new_cdclk_state->actual)) {
@@ -2544,8 +2600,6 @@ int intel_modeset_calc_cdclk(struct intel_atomic_state *state)
 		if (ret)
 			return ret;
 
-		new_cdclk_state->pipe = INVALID_PIPE;
-
 		drm_dbg_kms(&dev_priv->drm,
 			    "Modeset required for cdclk change\n");
 	}

drivers/gpu/drm/i915/i915_pci.c

@@ -953,6 +953,7 @@ static const struct intel_device_info adl_p_info = {
 	GEN12_FEATURES,
 	XE_LPD_FEATURES,
 	PLATFORM(INTEL_ALDERLAKE_P),
+	.has_cdclk_crawl = 1,
 	.require_force_probe = 1,
 	.display.has_modular_fia = 1,
 	.platform_engine_mask =

drivers/gpu/drm/i915/i915_reg.h

@@ -10981,6 +10981,8 @@ enum skl_power_gate {
 #define BXT_DE_PLL_ENABLE		_MMIO(0x46070)
 #define   BXT_DE_PLL_PLL_ENABLE		(1 << 31)
 #define   BXT_DE_PLL_LOCK		(1 << 30)
+#define   BXT_DE_PLL_FREQ_REQ		(1 << 23)
+#define   BXT_DE_PLL_FREQ_REQ_ACK	(1 << 22)
 #define   CNL_CDCLK_PLL_RATIO(x)	(x)
 #define   CNL_CDCLK_PLL_RATIO_MASK	0xff
 

drivers/gpu/drm/i915/intel_device_info.h

@@ -185,6 +185,8 @@ struct intel_device_info {
 
 	u8 abox_mask;
 
+	u8 has_cdclk_crawl;  /* does support CDCLK crawling */
+
 #define DEFINE_FLAG(name) u8 name:1
 	DEV_INFO_FOR_EACH_FLAG(DEFINE_FLAG);
 #undef DEFINE_FLAG