Patch "drm/i915: Bail out of pipe config compute loop on LPT" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915: Bail out of pipe config compute loop on LPT

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-bail-out-of-pipe-config-compute-loop-on-lpt.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Daniel Vetter <[email protected]>
Date: Tue, 3 May 2016 10:33:01 +0200
Subject: drm/i915: Bail out of pipe config compute loop on LPT

From: Daniel Vetter <[email protected]>

commit 2700818ac9f935d8590715eecd7e8cadbca552b6 upstream.

LPT is pch, so might run into the fdi bandwidth constraint (especially since it has only 2 lanes). But right now we just force pipe_bpp back to 24, resulting in a nice loop (which we bail out with a loud WARN_ON). Fix this.

Cc: Chris Wilson <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
References: https://bugs.freedesktop.org/show_bug.cgi?id=93477

---
 drivers/gpu/drm/i915/intel_crt.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

@@ -248,8 +248,14 @@ static bool intel_crt_compute_config(str
 		pipe_config->has_pch_encoder = true;
 
 	/* LPT FDI RX only supports 8bpc. */
-	if (HAS_PCH_LPT(dev))
+	if (HAS_PCH_LPT(dev)) {
+		if (pipe_config->bw_constrained && pipe_config->pipe_bpp < 24) {
+			DRM_DEBUG_KMS("LPT only supports 24bpp\n");
+			return false;
+		}
+
 		pipe_config->pipe_bpp = 24;
+	}
 
 	/* FDI must always be 2.7 GHz */
 	if (HAS_DDI(dev)) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/drm-i915-bail-out-of-pipe-config-compute-loop-on-lpt.patch