drm/i915: Support variable cursor height on ivb+

IVB introduced the CUR_FBC_CTL register which allows reducing the cursor
height down to 8 lines from the otherwise square cursor dimensions.
Implement support for it. CUR_FBC_CTL can't be used when the cursor
is rotated.

Commandeer the otherwise unused cursor->cursor.size to track the
current value of CUR_FBC_CTL to optimize away redundant CUR_FBC_CTL
writes, and to notice when we need to arm the update via CURBASE if
just CUR_FBC_CTL changes.

v2: Reverse the gen check to make it sane
v3: Only enable CUR_FBC_CTL when cursor is enabled, adapt to
    earlier code changes which means we now actually turn off
    the cursor when we're supposed to unlike v2
v4: Add a comment about rotation vs. CUR_FBC_CTL,
    rebase due to 'dirty' (Chris)
v5: Rebase to the atomic world
    Handle 180 degree rotation
    Add HAS_CUR_FBC()
v6: Rebase
v7: Rebase due to I915_WRITE_FW/uncore.lock
    s/size/fbc_ctl/

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-12-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -2808,6 +2808,7 @@ intel_info(const struct drm_i915_private *dev_priv)
 #define HAS_FW_BLC(dev_priv) 	(INTEL_GEN(dev_priv) > 2)
 #define HAS_PIPE_CXSR(dev_priv) ((dev_priv)->info.has_pipe_cxsr)
 #define HAS_FBC(dev_priv)	((dev_priv)->info.has_fbc)
+#define HAS_CUR_FBC(dev_priv)	(!HAS_GMCH_DISPLAY(dev_priv) && INTEL_INFO(dev_priv)->gen >= 7)
 
 #define HAS_IPS(dev_priv)	(IS_HSW_ULT(dev_priv) || IS_BROADWELL(dev_priv))
 

drivers/gpu/drm/i915/i915_reg.h

@@ -5449,7 +5449,9 @@ enum {
 #define   CURSOR_POS_SIGN       0x8000
 #define   CURSOR_X_SHIFT        0
 #define   CURSOR_Y_SHIFT        16
-#define CURSIZE			_MMIO(0x700a0)
+#define CURSIZE			_MMIO(0x700a0) /* 845/865 */
+#define _CUR_FBC_CTL_A		0x700a0 /* ivb+ */
+#define   CUR_FBC_CTL_EN	(1 << 31)
 #define _CURBCNTR		0x700c0
 #define _CURBBASE		0x700c4
 #define _CURBPOS		0x700c8
@@ -5465,6 +5467,7 @@ enum {
 #define CURCNTR(pipe) _CURSOR2(pipe, _CURACNTR)
 #define CURBASE(pipe) _CURSOR2(pipe, _CURABASE)
 #define CURPOS(pipe) _CURSOR2(pipe, _CURAPOS)
+#define CUR_FBC_CTL(pipe) _CURSOR2(pipe, _CUR_FBC_CTL_A)
 
 #define CURSOR_A_OFFSET 0x70080
 #define CURSOR_B_OFFSET 0x700c0

drivers/gpu/drm/i915/intel_display.c

@@ -9373,17 +9373,16 @@ static u32 i9xx_cursor_ctl(const struct intel_crtc_state *crtc_state,
 
 static bool i9xx_cursor_size_ok(const struct intel_plane_state *plane_state)
 {
+	struct drm_i915_private *dev_priv =
+		to_i915(plane_state->base.plane->dev);
 	int width = plane_state->base.crtc_w;
 	int height = plane_state->base.crtc_h;
 
 	if (!intel_cursor_size_ok(plane_state))
 		return false;
 
-	/*
-	 * Cursors are limited to a few power-of-two
-	 * sizes, and they must be square.
-	 */
-	switch (width | height) {
+	/* Cursor width is limited to a few power-of-two sizes */
+	switch (width) {
 	case 256:
 	case 128:
 	case 64:
@@ -9392,6 +9391,21 @@ static bool i9xx_cursor_size_ok(const struct intel_plane_state *plane_state)
 		return false;
 	}
 
+	/*
+	 * IVB+ have CUR_FBC_CTL which allows an arbitrary cursor
+	 * height from 8 lines up to the cursor width, when the
+	 * cursor is not rotated. Everything else requires square
+	 * cursors.
+	 */
+	if (HAS_CUR_FBC(dev_priv) &&
+	    plane_state->base.rotation & DRM_ROTATE_0) {
+		if (height < 8 || height > width)
+			return false;
+	} else {
+		if (height != width)
+			return false;
+	}
+
 	return true;
 }
 
@@ -9453,12 +9467,15 @@ static void i9xx_update_cursor(struct intel_plane *plane,
 {
 	struct drm_i915_private *dev_priv = to_i915(plane->base.dev);
 	enum pipe pipe = plane->pipe;
-	u32 cntl = 0, base = 0, pos = 0;
+	u32 cntl = 0, base = 0, pos = 0, fbc_ctl = 0;
 	unsigned long irqflags;
 
 	if (plane_state && plane_state->base.visible) {
 		cntl = plane_state->ctl;
 
+		if (plane_state->base.crtc_h != plane_state->base.crtc_w)
+			fbc_ctl = CUR_FBC_CTL_EN | (plane_state->base.crtc_h - 1);
+
 		base = intel_cursor_base(plane_state);
 		pos = intel_cursor_position(plane_state);
 	}
@@ -9468,10 +9485,14 @@ static void i9xx_update_cursor(struct intel_plane *plane,
 	if (plane->cursor.cntl != cntl)
 		I915_WRITE_FW(CURCNTR(pipe), cntl);
 
+	if (plane->cursor.size != fbc_ctl)
+		I915_WRITE_FW(CUR_FBC_CTL(pipe), fbc_ctl);
+
 	if (cntl)
 		I915_WRITE_FW(CURPOS(pipe), pos);
 
 	if (plane->cursor.cntl != cntl ||
+	    plane->cursor.size != fbc_ctl ||
 	    plane->cursor.base != base)
 		I915_WRITE_FW(CURBASE(pipe), base);
 
@@ -9481,6 +9502,7 @@ static void i9xx_update_cursor(struct intel_plane *plane,
 
 	plane->cursor.cntl = cntl;
 	plane->cursor.base = base;
+	plane->cursor.size = fbc_ctl;
 }
 
 static void i9xx_disable_cursor(struct intel_plane *plane,
@@ -13822,7 +13844,9 @@ intel_cursor_plane_create(struct drm_i915_private *dev_priv,
 
 	cursor->cursor.base = ~0;
 	cursor->cursor.cntl = ~0;
-	cursor->cursor.size = ~0;
+
+	if (IS_I845G(dev_priv) || IS_I865G(dev_priv) || HAS_CUR_FBC(dev_priv))
+		cursor->cursor.size = ~0;
 
 	ret = drm_universal_plane_init(&dev_priv->drm, &cursor->base,
 				       0, &intel_cursor_plane_funcs,