drm/i915: BDW clock change support

Add support for changing cdclk frequency during runtime on BDW.

Also with IPS enabled the actual pixel rate mustn't exceed 95% of cdclk,
so take that into account when computing the max pixel rate.

v2: Grab rps.hw_lock around sandybridge_pcode_write()
v3: Rebase due to power well vs. .global_resources() reordering
v4: Rebased to the latest
v5: Rebased to the latest
v6: Patch order shuffle so that Broadwell CD clock change is
    applied before the patch for Haswell CD clock change
v7: Fix for patch style problems
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -6705,6 +6705,7 @@ enum skl_disp_power_wells {
 #define	  GEN6_PCODE_READ_RC6VIDS		0x5
 #define     GEN6_ENCODE_RC6_VID(mv)		(((mv) - 245) / 5)
 #define     GEN6_DECODE_RC6_VID(vids)		(((vids) * 5) + 245)
+#define   BDW_PCODE_DISPLAY_FREQ_CHANGE_REQ	0x18
 #define   GEN9_PCODE_READ_MEM_LATENCY		0x6
 #define     GEN9_MEM_LATENCY_LEVEL_MASK		0xFF
 #define     GEN9_MEM_LATENCY_LEVEL_1_5_SHIFT	8
@@ -7167,6 +7168,7 @@ enum skl_disp_power_wells {
 #define  LCPLL_CLK_FREQ_337_5_BDW	(2<<26)
 #define  LCPLL_CLK_FREQ_675_BDW		(3<<26)
 #define  LCPLL_CD_CLOCK_DISABLE		(1<<25)
+#define  LCPLL_ROOT_CD_CLOCK_DISABLE	(1<<24)
 #define  LCPLL_CD2X_CLOCK_DISABLE	(1<<23)
 #define  LCPLL_POWER_DOWN_ALLOW		(1<<22)
 #define  LCPLL_CD_SOURCE_FCLK		(1<<21)

drivers/gpu/drm/i915/intel_display.c

@@ -5751,7 +5751,22 @@ static void intel_update_max_cdclk(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (IS_VALLEYVIEW(dev)) {
+	if (IS_BROADWELL(dev))  {
+		/*
+		 * FIXME with extra cooling we can allow
+		 * 540 MHz for ULX and 675 Mhz for ULT.
+		 * How can we know if extra cooling is
+		 * available? PCI ID, VTB, something else?
+		 */
+		if (I915_READ(FUSE_STRAP) & HSW_CDCLK_LIMIT)
+			dev_priv->max_cdclk_freq = 450000;
+		else if (IS_BDW_ULX(dev))
+			dev_priv->max_cdclk_freq = 450000;
+		else if (IS_BDW_ULT(dev))
+			dev_priv->max_cdclk_freq = 540000;
+		else
+			dev_priv->max_cdclk_freq = 675000;
+	} else if (IS_VALLEYVIEW(dev)) {
 		dev_priv->max_cdclk_freq = 400000;
 	} else {
 		/* otherwise assume cdclk is fixed */
@@ -6621,13 +6636,11 @@ static bool pipe_config_supports_ips(struct drm_i915_private *dev_priv,
 		return true;
 
 	/*
-	 * FIXME if we compare against max we should then
-	 * increase the cdclk frequency when the current
-	 * value is too low. The other option is to compare
-	 * against the cdclk frequency we're going have post
-	 * modeset (ie. one we computed using other constraints).
-	 * Need to measure whether using a lower cdclk w/o IPS
-	 * is better or worse than a higher cdclk w/ IPS.
+	 * We compare against max which means we must take
+	 * the increased cdclk requirement into account when
+	 * calculating the new cdclk.
+	 *
+	 * Should measure whether using a lower cdclk w/o IPS
 	 */
 	return ilk_pipe_pixel_rate(pipe_config) <=
 		dev_priv->max_cdclk_freq * 95 / 100;
@@ -9608,6 +9621,182 @@ static void broxton_modeset_global_resources(struct drm_atomic_state *old_state)
 		broxton_set_cdclk(dev, req_cdclk);
 }
 
+/* compute the max rate for new configuration */
+static int ilk_max_pixel_rate(struct drm_i915_private *dev_priv)
+{
+	struct drm_device *dev = dev_priv->dev;
+	struct intel_crtc *intel_crtc;
+	struct drm_crtc *crtc;
+	int max_pixel_rate = 0;
+	int pixel_rate;
+
+	for_each_crtc(dev, crtc) {
+		if (!crtc->state->enable)
+			continue;
+
+		intel_crtc = to_intel_crtc(crtc);
+		pixel_rate = ilk_pipe_pixel_rate(intel_crtc->config);
+
+		/* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
+		if (IS_BROADWELL(dev) && intel_crtc->config->ips_enabled)
+			pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95);
+
+		max_pixel_rate = max(max_pixel_rate, pixel_rate);
+	}
+
+	return max_pixel_rate;
+}
+
+static void broadwell_set_cdclk(struct drm_device *dev, int cdclk)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t val, data;
+	int ret;
+
+	if (WARN((I915_READ(LCPLL_CTL) &
+		  (LCPLL_PLL_DISABLE | LCPLL_PLL_LOCK |
+		   LCPLL_CD_CLOCK_DISABLE | LCPLL_ROOT_CD_CLOCK_DISABLE |
+		   LCPLL_CD2X_CLOCK_DISABLE | LCPLL_POWER_DOWN_ALLOW |
+		   LCPLL_CD_SOURCE_FCLK)) != LCPLL_PLL_LOCK,
+		 "trying to change cdclk frequency with cdclk not enabled\n"))
+		return;
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+	ret = sandybridge_pcode_write(dev_priv,
+				      BDW_PCODE_DISPLAY_FREQ_CHANGE_REQ, 0x0);
+	mutex_unlock(&dev_priv->rps.hw_lock);
+	if (ret) {
+		DRM_ERROR("failed to inform pcode about cdclk change\n");
+		return;
+	}
+
+	val = I915_READ(LCPLL_CTL);
+	val |= LCPLL_CD_SOURCE_FCLK;
+	I915_WRITE(LCPLL_CTL, val);
+
+	if (wait_for_atomic_us(I915_READ(LCPLL_CTL) &
+			       LCPLL_CD_SOURCE_FCLK_DONE, 1))
+		DRM_ERROR("Switching to FCLK failed\n");
+
+	val = I915_READ(LCPLL_CTL);
+	val &= ~LCPLL_CLK_FREQ_MASK;
+
+	switch (cdclk) {
+	case 450000:
+		val |= LCPLL_CLK_FREQ_450;
+		data = 0;
+		break;
+	case 540000:
+		val |= LCPLL_CLK_FREQ_54O_BDW;
+		data = 1;
+		break;
+	case 337500:
+		val |= LCPLL_CLK_FREQ_337_5_BDW;
+		data = 2;
+		break;
+	case 675000:
+		val |= LCPLL_CLK_FREQ_675_BDW;
+		data = 3;
+		break;
+	default:
+		WARN(1, "invalid cdclk frequency\n");
+		return;
+	}
+
+	I915_WRITE(LCPLL_CTL, val);
+
+	val = I915_READ(LCPLL_CTL);
+	val &= ~LCPLL_CD_SOURCE_FCLK;
+	I915_WRITE(LCPLL_CTL, val);
+
+	if (wait_for_atomic_us((I915_READ(LCPLL_CTL) &
+				LCPLL_CD_SOURCE_FCLK_DONE) == 0, 1))
+		DRM_ERROR("Switching back to LCPLL failed\n");
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+	sandybridge_pcode_write(dev_priv, HSW_PCODE_DE_WRITE_FREQ_REQ, data);
+	mutex_unlock(&dev_priv->rps.hw_lock);
+
+	intel_update_cdclk(dev);
+
+	WARN(cdclk != dev_priv->cdclk_freq,
+	     "cdclk requested %d kHz but got %d kHz\n",
+	     cdclk, dev_priv->cdclk_freq);
+}
+
+static int broadwell_calc_cdclk(struct drm_i915_private *dev_priv,
+			      int max_pixel_rate)
+{
+	int cdclk;
+
+	/*
+	 * FIXME should also account for plane ratio
+	 * once 64bpp pixel formats are supported.
+	 */
+	if (max_pixel_rate > 540000)
+		cdclk = 675000;
+	else if (max_pixel_rate > 450000)
+		cdclk = 540000;
+	else if (max_pixel_rate > 337500)
+		cdclk = 450000;
+	else
+		cdclk = 337500;
+
+	/*
+	 * FIXME move the cdclk caclulation to
+	 * compute_config() so we can fail gracegully.
+	 */
+	if (cdclk > dev_priv->max_cdclk_freq) {
+		DRM_ERROR("requested cdclk (%d kHz) exceeds max (%d kHz)\n",
+			  cdclk, dev_priv->max_cdclk_freq);
+		cdclk = dev_priv->max_cdclk_freq;
+	}
+
+	return cdclk;
+}
+
+static int broadwell_modeset_global_pipes(struct drm_atomic_state *state)
+{
+	struct drm_i915_private *dev_priv = to_i915(state->dev);
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+	int max_pixclk = ilk_max_pixel_rate(dev_priv);
+	int cdclk, i;
+
+	cdclk = broadwell_calc_cdclk(dev_priv, max_pixclk);
+
+	if (cdclk == dev_priv->cdclk_freq)
+		return 0;
+
+	/* add all active pipes to the state */
+	for_each_crtc(state->dev, crtc) {
+		if (!crtc->state->enable)
+			continue;
+
+		crtc_state = drm_atomic_get_crtc_state(state, crtc);
+		if (IS_ERR(crtc_state))
+			return PTR_ERR(crtc_state);
+	}
+
+	/* disable/enable all currently active pipes while we change cdclk */
+	for_each_crtc_in_state(state, crtc, crtc_state, i)
+		if (crtc_state->enable)
+			crtc_state->mode_changed = true;
+
+	return 0;
+}
+
+static void broadwell_modeset_global_resources(struct drm_atomic_state *state)
+{
+	struct drm_device *dev = state->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int max_pixel_rate = ilk_max_pixel_rate(dev_priv);
+	int req_cdclk = broadwell_calc_cdclk(dev_priv, max_pixel_rate);
+
+	if (req_cdclk != dev_priv->cdclk_freq)
+		broadwell_set_cdclk(dev, req_cdclk);
+}
+
 static int haswell_crtc_compute_clock(struct intel_crtc *crtc,
 				      struct intel_crtc_state *crtc_state)
 {
@@ -12788,8 +12977,12 @@ static int __intel_set_mode_checks(struct drm_atomic_state *state)
 	 * mode set on this crtc.  For other crtcs we need to use the
 	 * adjusted_mode bits in the crtc directly.
 	 */
-	if (IS_VALLEYVIEW(dev) || IS_BROXTON(dev)) {
+	if (IS_VALLEYVIEW(dev) || IS_BROXTON(dev) || IS_BROADWELL(dev)) {
+		if (IS_VALLEYVIEW(dev) || IS_BROXTON(dev))
 			ret = valleyview_modeset_global_pipes(state);
+		else
+			ret = broadwell_modeset_global_pipes(state);
+
 		if (ret)
 			return ret;
 	}
@@ -14677,6 +14870,9 @@ static void intel_init_display(struct drm_device *dev)
 		dev_priv->display.fdi_link_train = ivb_manual_fdi_link_train;
 	} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
 		dev_priv->display.fdi_link_train = hsw_fdi_link_train;
+		if (IS_BROADWELL(dev))
+			dev_priv->display.modeset_global_resources =
+				broadwell_modeset_global_resources;
 	} else if (IS_VALLEYVIEW(dev)) {
 		dev_priv->display.modeset_global_resources =
 			valleyview_modeset_global_resources;