Patch "drm/radeon: fix DP link training issue with second 4K monitor" has been added to the 4.5-stable tree

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

drm/radeon: fix DP link training issue with second 4K monitor

to the 4.5-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-radeon-fix-dp-link-training-issue-with-second-4k-monitor.patch
and it can be found in the queue-4.5 subdirectory.

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

From: Arindam Nath <[email protected]>
Date: Wed, 4 May 2016 23:39:59 +0530
Subject: drm/radeon: fix DP link training issue with second 4K monitor

From: Arindam Nath <[email protected]>

commit 1a738347df2ee4977459a8776fe2c62196bdcb1b upstream.

There is an issue observed when we hotplug a second DP 4K monitor to the system. Sometimes, the link training fails for the second monitor after HPD interrupt generation.

The issue happens when some queued or deferred transactions are already present on the AUX channel when we initiate a new transcation to (say) get DPCD or during link training.

We set AUX_IGNORE_HPD_DISCON bit in the AUX_CONTROL register so that we can ignore any such deferred transactions when a new AUX transaction is initiated.

---
 drivers/gpu/drm/radeon/radeon_dp_auxch.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -105,7 +105,7 @@ radeon_dp_aux_transfer_native(struct drm
 
 	tmp &= AUX_HPD_SEL(0x7);
 	tmp |= AUX_HPD_SEL(chan->rec.hpd);
-	tmp |= AUX_EN | AUX_LS_READ_EN;
+	tmp |= AUX_EN | AUX_LS_READ_EN | AUX_HPD_DISCON(0x1);
 
 	WREG32(AUX_CONTROL + aux_offset[instance], tmp);
 

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

queue-4.5/drm-radeon-fix-dp-link-training-issue-with-second-4k-monitor.patch