[3.16.y-ckt stable] Patch "drm/radeon: fix freeze for laptop with Turks/Thames GPU." has been added to staging queue

[Luis Henriques]

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

    drm/radeon: fix freeze for laptop with Turks/Thames GPU.

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt14.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 5c655b1623f75a1e8f836f68b6e25584ec8ec2d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= <jglisse at redhat.com>
Date: Fri, 5 Jun 2015 13:33:57 -0400
Subject: drm/radeon: fix freeze for laptop with Turks/Thames GPU.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 6dfd197283bffc23a2b046a7f065588de7e1fc1e upstream.

Laptop with Turks/Thames GPU will freeze if dpm is enabled. It seems
the SMC engine is relying on some state inside the CP engine. CP needs
to chew at least one packet for it to get in good state for dynamic
power management.

This patch simply disabled and re-enable DPM after the ring test which
is enough to avoid the freeze.

Signed-off-by: Jérôme Glisse <jglisse at redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/radeon/radeon_device.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index d024389c4272..e5ed5ee9d832 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1374,6 +1374,21 @@ int radeon_device_init(struct radeon_device *rdev,
 			goto failed;
 	}

+	/*
+	 * Turks/Thames GPU will freeze whole laptop if DPM is not restarted
+	 * after the CP ring have chew one packet at least. Hence here we stop
+	 * and restart DPM after the radeon_ib_ring_tests().
+	 */
+	if (rdev->pm.dpm_enabled &&
+	    (rdev->pm.pm_method == PM_METHOD_DPM) &&
+	    (rdev->family == CHIP_TURKS) &&
+	    (rdev->flags & RADEON_IS_MOBILITY)) {
+		mutex_lock(&rdev->pm.mutex);
+		radeon_dpm_disable(rdev);
+		radeon_dpm_enable(rdev);
+		mutex_unlock(&rdev->pm.mutex);
+	}
+
 	if ((radeon_testing & 1)) {
 		if (rdev->accel_working)
 			radeon_test_moves(rdev);