[Intel-gfx] [PATCH 3/4] drm/i915: Try harder to get FBC

[Runyan, Arthur J]

You give me too much credit.  I just gave you an explanation of what the hardware does, then you ran with it.

On Thu, Jun 19, 2014 at 12:06:13PM -0700, Ben Widawsky wrote:
+		DRM_INFO("Reducing the compressed framebuffer size. This may lead to increased power. Try to increase stolen memory size if available in BIOS.\n");

I prefer "This may lead to less power savings than a non-reduced size." since FBC is still going to save power.

 	dpfc_ctl = DPFC_CTL_PLANE(intel_crtc->plane);
 	if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
+		dev_priv->fbc.threshold++;
+
+	switch (dev_priv->fbc.threshold) {
+	case 4:
+		dpfc_ctl |= DPFC_CTL_LIMIT_4X;
+		break;
+	case 2:
 		dpfc_ctl |= DPFC_CTL_LIMIT_2X;
-	else
+		break;
+	case 1:
 		dpfc_ctl |= DPFC_CTL_LIMIT_1X;
+		break;
+	}

I Am Not A Coder, but at a glance it looks like the ++ could lead to undefined case 3 when you want case 4.