drm/i915: Polish the skl+ plane keyval/msk/max register setup

Due to the constant alpha we're going to have to program two of
the the tree keying registers anyway, so might as well always
program all three.

And parametrize the plane constant alpha define while at it.

v2: Rebase due to input CSC

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181107184138.31359-1-ville.syrjala@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -6559,7 +6559,7 @@ enum {
 #define  PLANE_KEYMSK_ALPHA_ENABLE		(1 << 31)
 #define _PLANE_KEYMAX_1_A			0x701a0
 #define _PLANE_KEYMAX_2_A			0x702a0
-#define  PLANE_KEYMAX_ALPHA_SHIFT		24
+#define  PLANE_KEYMAX_ALPHA(a)			((a) << 24)
 #define _PLANE_AUX_DIST_1_A			0x701c0
 #define _PLANE_AUX_DIST_2_A			0x702c0
 #define _PLANE_AUX_OFFSET_1_A			0x701c4

drivers/gpu/drm/i915/intel_sprite.c

@@ -478,13 +478,20 @@ skl_program_plane(struct intel_plane *plane,
 	uint32_t src_h = drm_rect_height(&plane_state->base.src) >> 16;
 	struct intel_plane *linked = plane_state->linked_plane;
 	const struct drm_framebuffer *fb = plane_state->base.fb;
+	u8 alpha = plane_state->base.alpha >> 8;
 	unsigned long irqflags;
-	u32 keymsk = 0, keymax = 0;
+	u32 keymsk, keymax;
 
 	/* Sizes are 0 based */
 	src_w--;
 	src_h--;
 
+	keymax = (key->max_value & 0xffffff) | PLANE_KEYMAX_ALPHA(alpha);
+
+	keymsk = key->channel_mask & 0x3ffffff;
+	if (alpha < 0xff)
+		keymsk |= PLANE_KEYMSK_ALPHA_ENABLE;
+
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
 
 	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
@@ -494,18 +501,7 @@ skl_program_plane(struct intel_plane *plane,
 	if (fb->format->is_yuv && icl_is_hdr_plane(plane))
 		icl_program_input_csc_coeff(crtc_state, plane_state);
 
-	if (key->flags) {
-		I915_WRITE_FW(PLANE_KEYVAL(pipe, plane_id), key->min_value);
-
-		keymax |= key->max_value & 0xffffff;
-		keymsk |= key->channel_mask & 0x3ffffff;
-	}
-
-	keymax |= (plane_state->base.alpha >> 8) << PLANE_KEYMAX_ALPHA_SHIFT;
-
-	if (plane_state->base.alpha < 0xff00)
-		keymsk |= PLANE_KEYMSK_ALPHA_ENABLE;
-
+	I915_WRITE_FW(PLANE_KEYVAL(pipe, plane_id), key->min_value);
 	I915_WRITE_FW(PLANE_KEYMAX(pipe, plane_id), keymax);
 	I915_WRITE_FW(PLANE_KEYMSK(pipe, plane_id), keymsk);