Patch "drm/i915: shut up gen8+ SDE irq dmesg noise" 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: shut up gen8+ SDE irq dmesg noise

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-shut-up-gen8-sde-irq-dmesg-noise.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: Fri, 23 Oct 2015 10:56:12 +0200
Subject: drm/i915: shut up gen8+ SDE irq dmesg noise

From: Daniel Vetter <[email protected]>

commit 97e5ed1111dcc5300a0f59a55248cd243937a8ab upstream.

We get tons of cases where the master interrupt handler apparently set a bit, with the SDEIIR disagreeing. No idea what's going on there, but it's consistent on gen8+, no one seems to care about it and it's making CI results flaky.

Shut it up.

No idea what's going on here, but we've had fun with PCH interrupts before:

commit 44498aea293b37af1d463acd9658cdce1ecdf427

Author: Paulo Zanoni <[email protected]>
Date:   Fri Feb 22 17:05:28 2013 -0300

drm/i915: also disable south interrupts when handling them

Note that there's a regression report in Bugzilla, and other regression reports on the mailing lists keep croping up. But no ill effects have ever been reported. But for paranoia still keep the message at a debug level as a breadcrumb, just in case.

This message was introduced in

commit 38cc46d73ed99dd7002f1406002e52d7975d16cc

Author: Oscar Mateo <[email protected]>
Date:   Mon Jun 16 16:10:59 2014 +0100

drm/i915/bdw: Ack interrupts before handling them (GEN8)

v2: Improve commit message a bit.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92084
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=80896

---
 drivers/gpu/drm/i915/i915_irq.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

@@ -2354,9 +2354,13 @@ static irqreturn_t gen8_irq_handler(int
 				spt_irq_handler(dev, pch_iir);
 			else
 				cpt_irq_handler(dev, pch_iir);
-		} else
-			DRM_ERROR("The master control interrupt lied (SDE)!\n");
-
+		} else {
+			/*
+			 * Like on previous PCH there seems to be something
+			 * fishy going on with forwarding PCH interrupts.
+			 */
+			DRM_DEBUG_DRIVER("The master control interrupt lied (SDE)!\n");
+		}
 	}
 
 	I915_WRITE_FW(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);

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

queue-4.4/drm-gma500-use-correct-unref-in-the-gem-bo-create-function.patch queue-4.4/drm-i915-shut-up-gen8-sde-irq-dmesg-noise.patch