[4.2.y-ckt stable] Patch "drm/amdgpu: return from atombios_dp_get_dpcd only when error" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/amdgpu: return from atombios_dp_get_dpcd only when error

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 50df6cbd13b7f2f70662785fb9206a0ae7d1ba7e Mon Sep 17 00:00:00 2001
From: Arindam Nath <arindam.nath at amd.com>
Date: Wed, 2 Mar 2016 17:19:01 +0530
Subject: drm/amdgpu: return from atombios_dp_get_dpcd only when error

commit 0b39c531cfa12dad54eac238c2e303b994df1ef7 upstream.

In amdgpu_connector_hotplug(), we need to start DP link
training only after we have received DPCD. The function
amdgpu_atombios_dp_get_dpcd() returns non-zero value only
when an error condition is met, otherwise returns zero.
So in case the function encounters an error, we need to
skip rest of the code and return from amdgpu_connector_hotplug()
immediately. Only when we are successfull in reading DPCD
pin, we should carry on with turning-on the monitor.

Signed-off-by: Arindam Nath <arindam.nath at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
index 89c3dd6..119cdc2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -77,7 +77,7 @@ void amdgpu_connector_hotplug(struct drm_connector *connector)
 			} else if (amdgpu_atombios_dp_needs_link_train(amdgpu_connector)) {
 				/* Don't try to start link training before we
 				 * have the dpcd */
-				if (!amdgpu_atombios_dp_get_dpcd(amdgpu_connector))
+				if (amdgpu_atombios_dp_get_dpcd(amdgpu_connector))
 					return;

 				/* set it to OFF so that drm_helper_connector_dpms()
--
2.7.0