drm/i915: Add the support of memory self-refresh on Ironlake

Update the self-refresh watermark for display plane/cursor and enable
the memory self-refresh on Ironlake. The watermark is also updated for
the active display plane.

More than 1W idle power is saved on one Ironlake laptop after enabling
memory self-refresh.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -2030,6 +2030,43 @@
 #define PINEVIEW_CURSOR_DFT_WM	0
 #define PINEVIEW_CURSOR_GUARD_WM	5
 
+
+/* define the Watermark register on Ironlake */
+#define WM0_PIPEA_ILK		0x45100
+#define  WM0_PIPE_PLANE_MASK	(0x7f<<16)
+#define  WM0_PIPE_PLANE_SHIFT	16
+#define  WM0_PIPE_SPRITE_MASK	(0x3f<<8)
+#define  WM0_PIPE_SPRITE_SHIFT	8
+#define  WM0_PIPE_CURSOR_MASK	(0x1f)
+
+#define WM0_PIPEB_ILK		0x45104
+#define WM1_LP_ILK		0x45108
+#define  WM1_LP_SR_EN		(1<<31)
+#define  WM1_LP_LATENCY_SHIFT	24
+#define  WM1_LP_LATENCY_MASK	(0x7f<<24)
+#define  WM1_LP_SR_MASK		(0x1ff<<8)
+#define  WM1_LP_SR_SHIFT	8
+#define  WM1_LP_CURSOR_MASK	(0x3f)
+
+/* Memory latency timer register */
+#define MLTR_ILK		0x11222
+/* the unit of memory self-refresh latency time is 0.5us */
+#define  ILK_SRLT_MASK		0x3f
+
+/* define the fifo size on Ironlake */
+#define ILK_DISPLAY_FIFO	128
+#define ILK_DISPLAY_MAXWM	64
+#define ILK_DISPLAY_DFTWM	8
+
+#define ILK_DISPLAY_SR_FIFO	512
+#define ILK_DISPLAY_MAX_SRWM	0x1ff
+#define ILK_DISPLAY_DFT_SRWM	0x3f
+#define ILK_CURSOR_SR_FIFO	64
+#define ILK_CURSOR_MAX_SRWM	0x3f
+#define ILK_CURSOR_DFT_SRWM	8
+
+#define ILK_FIFO_LINE_SIZE	64
+
 /*
  * The two pipe frame counter registers are not synchronized, so
  * reading a stable value is somewhat tricky. The following code
@@ -2310,8 +2347,15 @@
 #define GTIIR   0x44018
 #define GTIER   0x4401c
 
+#define ILK_DISPLAY_CHICKEN2	0x42004
+#define  ILK_DPARB_GATE	(1<<22)
+#define  ILK_VSDPFD_FULL	(1<<21)
+#define ILK_DSPCLK_GATE		0x42020
+#define  ILK_DPARB_CLK_GATE	(1<<5)
+
 #define DISP_ARB_CTL	0x45000
 #define  DISP_TILE_SURFACE_SWIZZLING	(1<<13)
+#define  DISP_FBC_WM_DIS		(1<<15)
 
 /* PCH */
 

drivers/gpu/drm/i915/intel_display.c

@@ -2527,6 +2527,30 @@ static struct intel_watermark_params i830_wm_info = {
 	I830_FIFO_LINE_SIZE
 };
 
+static struct intel_watermark_params ironlake_display_wm_info = {
+	ILK_DISPLAY_FIFO,
+	ILK_DISPLAY_MAXWM,
+	ILK_DISPLAY_DFTWM,
+	2,
+	ILK_FIFO_LINE_SIZE
+};
+
+static struct intel_watermark_params ironlake_display_srwm_info = {
+	ILK_DISPLAY_SR_FIFO,
+	ILK_DISPLAY_MAX_SRWM,
+	ILK_DISPLAY_DFT_SRWM,
+	2,
+	ILK_FIFO_LINE_SIZE
+};
+
+static struct intel_watermark_params ironlake_cursor_srwm_info = {
+	ILK_CURSOR_SR_FIFO,
+	ILK_CURSOR_MAX_SRWM,
+	ILK_CURSOR_DFT_SRWM,
+	2,
+	ILK_FIFO_LINE_SIZE
+};
+
 /**
  * intel_calculate_wm - calculate watermark level
  * @clock_in_khz: pixel clock
@@ -3014,6 +3038,108 @@ static void i830_update_wm(struct drm_device *dev, int planea_clock, int unused,
 	I915_WRITE(FW_BLC, fwater_lo);
 }
 
+#define ILK_LP0_PLANE_LATENCY		700
+
+static void ironlake_update_wm(struct drm_device *dev,  int planea_clock,
+		       int planeb_clock, int sr_hdisplay, int pixel_size)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int planea_wm, planeb_wm, cursora_wm, cursorb_wm;
+	int sr_wm, cursor_wm;
+	unsigned long line_time_us;
+	int sr_clock, entries_required;
+	u32 reg_value;
+
+	/* Calculate and update the watermark for plane A */
+	if (planea_clock) {
+		entries_required = ((planea_clock / 1000) * pixel_size *
+				     ILK_LP0_PLANE_LATENCY) / 1000;
+		entries_required = DIV_ROUND_UP(entries_required,
+				   ironlake_display_wm_info.cacheline_size);
+		planea_wm = entries_required +
+			    ironlake_display_wm_info.guard_size;
+
+		if (planea_wm > (int)ironlake_display_wm_info.max_wm)
+			planea_wm = ironlake_display_wm_info.max_wm;
+
+		cursora_wm = 16;
+		reg_value = I915_READ(WM0_PIPEA_ILK);
+		reg_value &= ~(WM0_PIPE_PLANE_MASK | WM0_PIPE_CURSOR_MASK);
+		reg_value |= (planea_wm << WM0_PIPE_PLANE_SHIFT) |
+			     (cursora_wm & WM0_PIPE_CURSOR_MASK);
+		I915_WRITE(WM0_PIPEA_ILK, reg_value);
+		DRM_DEBUG_KMS("FIFO watermarks For pipe A - plane %d, "
+				"cursor: %d\n", planea_wm, cursora_wm);
+	}
+	/* Calculate and update the watermark for plane B */
+	if (planeb_clock) {
+		entries_required = ((planeb_clock / 1000) * pixel_size *
+				     ILK_LP0_PLANE_LATENCY) / 1000;
+		entries_required = DIV_ROUND_UP(entries_required,
+				   ironlake_display_wm_info.cacheline_size);
+		planeb_wm = entries_required +
+			    ironlake_display_wm_info.guard_size;
+
+		if (planeb_wm > (int)ironlake_display_wm_info.max_wm)
+			planeb_wm = ironlake_display_wm_info.max_wm;
+
+		cursorb_wm = 16;
+		reg_value = I915_READ(WM0_PIPEB_ILK);
+		reg_value &= ~(WM0_PIPE_PLANE_MASK | WM0_PIPE_CURSOR_MASK);
+		reg_value |= (planeb_wm << WM0_PIPE_PLANE_SHIFT) |
+			     (cursorb_wm & WM0_PIPE_CURSOR_MASK);
+		I915_WRITE(WM0_PIPEB_ILK, reg_value);
+		DRM_DEBUG_KMS("FIFO watermarks For pipe B - plane %d, "
+				"cursor: %d\n", planeb_wm, cursorb_wm);
+	}
+
+	/*
+	 * Calculate and update the self-refresh watermark only when one
+	 * display plane is used.
+	 */
+	if (!planea_clock || !planeb_clock) {
+		int line_count;
+		/* Read the self-refresh latency. The unit is 0.5us */
+		int ilk_sr_latency = I915_READ(MLTR_ILK) & ILK_SRLT_MASK;
+
+		sr_clock = planea_clock ? planea_clock : planeb_clock;
+		line_time_us = ((sr_hdisplay * 1000) / sr_clock);
+
+		/* Use ns/us then divide to preserve precision */
+		line_count = ((ilk_sr_latency * 500) / line_time_us + 1000)
+			       / 1000;
+
+		/* calculate the self-refresh watermark for display plane */
+		entries_required = line_count * sr_hdisplay * pixel_size;
+		entries_required = DIV_ROUND_UP(entries_required,
+				   ironlake_display_srwm_info.cacheline_size);
+		sr_wm = entries_required +
+			ironlake_display_srwm_info.guard_size;
+
+		/* calculate the self-refresh watermark for display cursor */
+		entries_required = line_count * pixel_size * 64;
+		entries_required = DIV_ROUND_UP(entries_required,
+				   ironlake_cursor_srwm_info.cacheline_size);
+		cursor_wm = entries_required +
+			    ironlake_cursor_srwm_info.guard_size;
+
+		/* configure watermark and enable self-refresh */
+		reg_value = I915_READ(WM1_LP_ILK);
+		reg_value &= ~(WM1_LP_LATENCY_MASK | WM1_LP_SR_MASK |
+			       WM1_LP_CURSOR_MASK);
+		reg_value |= WM1_LP_SR_EN |
+			     (ilk_sr_latency << WM1_LP_LATENCY_SHIFT) |
+			     (sr_wm << WM1_LP_SR_SHIFT) | cursor_wm;
+
+		I915_WRITE(WM1_LP_ILK, reg_value);
+		DRM_DEBUG_KMS("self-refresh watermark: display plane %d "
+				"cursor %d\n", sr_wm, cursor_wm);
+
+	} else {
+		/* Turn off self refresh if both pipes are enabled */
+		I915_WRITE(WM1_LP_ILK, I915_READ(WM1_LP_ILK) & ~WM1_LP_SR_EN);
+	}
+}
 /**
  * intel_update_watermarks - update FIFO watermark values based on current modes
  *
@@ -4973,6 +5099,25 @@ void intel_init_clock_gating(struct drm_device *dev)
 		}
 
 		I915_WRITE(PCH_DSPCLK_GATE_D, dspclk_gate);
+
+		/*
+		 * According to the spec the following bits should be set in
+		 * order to enable memory self-refresh
+		 * The bit 22/21 of 0x42004
+		 * The bit 5 of 0x42020
+		 * The bit 15 of 0x45000
+		 */
+		if (IS_IRONLAKE(dev)) {
+			I915_WRITE(ILK_DISPLAY_CHICKEN2,
+					(I915_READ(ILK_DISPLAY_CHICKEN2) |
+					ILK_DPARB_GATE | ILK_VSDPFD_FULL));
+			I915_WRITE(ILK_DSPCLK_GATE,
+					(I915_READ(ILK_DSPCLK_GATE) |
+						ILK_DPARB_CLK_GATE));
+			I915_WRITE(DISP_ARB_CTL,
+					(I915_READ(DISP_ARB_CTL) |
+						DISP_FBC_WM_DIS));
+		}
 		return;
 	} else if (IS_G4X(dev)) {
 		uint32_t dspclk_gate;
@@ -5088,9 +5233,18 @@ static void intel_init_display(struct drm_device *dev)
 			i830_get_display_clock_speed;
 
 	/* For FIFO watermark updates */
-	if (HAS_PCH_SPLIT(dev))
-		dev_priv->display.update_wm = NULL;
-	else if (IS_PINEVIEW(dev)) {
+	if (HAS_PCH_SPLIT(dev)) {
+		if (IS_IRONLAKE(dev)) {
+			if (I915_READ(MLTR_ILK) & ILK_SRLT_MASK)
+				dev_priv->display.update_wm = ironlake_update_wm;
+			else {
+				DRM_DEBUG_KMS("Failed to get proper latency. "
+					      "Disable CxSR\n");
+				dev_priv->display.update_wm = NULL;
+			}
+		} else
+			dev_priv->display.update_wm = NULL;
+	} else if (IS_PINEVIEW(dev)) {
 		if (!intel_get_cxsr_latency(IS_PINEVIEW_G(dev),
 					    dev_priv->fsb_freq,
 					    dev_priv->mem_freq)) {