drm/i915: Allow disabling the destination colorkey for overlay

Sometimes userspace wants a true overlay that is never clipped. In such
cases, we need to disable the destination colorkey. However, it is
currently unconditionally enabled in the overlay with no means of
disabling. So rectify that by always default to on, and extending the
UPDATE_ATTR ioctl to support explicit disabling of the colorkey.

This is contrast to the spite code which requires explicit enabling of
either the destination or source colorkey. Handling source colorkey is
still todo for the overlay. (Of course it may be worth migrating overlay
to sprite before then.)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_overlay.c

@@ -175,7 +175,8 @@ struct intel_overlay {
 	bool active;
 	bool pfit_active;
 	u32 pfit_vscale_ratio; /* shifted-point number, (1<<12) == 1.0 */
-	u32 color_key;
+	u32 color_key:24;
+	u32 color_key_enabled:1;
 	u32 brightness, contrast, saturation;
 	u32 old_xscale, old_yscale;
 	/* register access */
@@ -630,31 +631,36 @@ static void update_colorkey(struct intel_overlay *overlay,
 			    struct overlay_registers __iomem *regs)
 {
 	u32 key = overlay->color_key;
+	u32 flags;
+
+	flags = 0;
+	if (overlay->color_key_enabled)
+		flags |= DST_KEY_ENABLE;
 
 	switch (overlay->crtc->base.primary->fb->bits_per_pixel) {
 	case 8:
-		iowrite32(0, &regs->DCLRKV);
-		iowrite32(CLK_RGB8I_MASK | DST_KEY_ENABLE, &regs->DCLRKM);
+		key = 0;
+		flags |= CLK_RGB8I_MASK;
 		break;
 
 	case 16:
 		if (overlay->crtc->base.primary->fb->depth == 15) {
-			iowrite32(RGB15_TO_COLORKEY(key), &regs->DCLRKV);
-			iowrite32(CLK_RGB15_MASK | DST_KEY_ENABLE,
-				  &regs->DCLRKM);
+			key = RGB15_TO_COLORKEY(key);
+			flags |= CLK_RGB15_MASK;
 		} else {
-			iowrite32(RGB16_TO_COLORKEY(key), &regs->DCLRKV);
-			iowrite32(CLK_RGB16_MASK | DST_KEY_ENABLE,
-				  &regs->DCLRKM);
+			key = RGB16_TO_COLORKEY(key);
+			flags |= CLK_RGB16_MASK;
 		}
 		break;
 
 	case 24:
 	case 32:
-		iowrite32(key, &regs->DCLRKV);
-		iowrite32(CLK_RGB24_MASK | DST_KEY_ENABLE, &regs->DCLRKM);
+		flags |= CLK_RGB24_MASK;
 		break;
 	}
+
+	iowrite32(key, &regs->DCLRKV);
+	iowrite32(flags, &regs->DCLRKM);
 }
 
 static u32 overlay_cmd_reg(struct put_image_params *params)
@@ -1329,6 +1335,7 @@ int intel_overlay_attrs(struct drm_device *dev, void *data,
 			I915_WRITE(OGAMC5, attrs->gamma5);
 		}
 	}
+	overlay->color_key_enabled = (attrs->flags & I915_OVERLAY_DISABLE_DEST_COLORKEY) == 0;
 
 	ret = 0;
 out_unlock:
@@ -1392,6 +1399,7 @@ void intel_setup_overlay(struct drm_device *dev)
 
 	/* init all values */
 	overlay->color_key = 0x0101fe;
+	overlay->color_key_enabled = true;
 	overlay->brightness = -19;
 	overlay->contrast = 75;
 	overlay->saturation = 146;

include/uapi/drm/i915_drm.h

@@ -996,6 +996,7 @@ struct drm_intel_overlay_put_image {
 /* flags */
 #define I915_OVERLAY_UPDATE_ATTRS	(1<<0)
 #define I915_OVERLAY_UPDATE_GAMMA	(1<<1)
+#define I915_OVERLAY_DISABLE_DEST_COLORKEY	(1<<2)
 struct drm_intel_overlay_attrs {
 	__u32 flags;
 	__u32 color_key;