From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: Thu, 14 Sep 2017 14:01:00 +0200
Subject: drm/exynos: Fix locking in the suspend/resume paths
Git-commit: 5baf6bb0fd2388742a0846cc7bcacee6dec78235
Patch-mainline: v4.14-rc2
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Commit 48a92916729b ("drm/exynos: use drm_for_each_connector_iter()")
replaced unsafe drm_for_each_connector() with drm_for_each_connector_iter()
and removed surrounding drm_modeset_lock calls. However, that lock was
there not only to protect unsafe drm_for_each_connector(), but it was also
required to be held by the dpms code which was called from the loop body.
This patch restores those drm_modeset_lock calls to fix broken suspend
and resume of Exynos DRM subsystem in v4.13 kernel.

Fixes: 48a92916729b ("drm/exynos: use drm_for_each_connector_iter()")
CC: stable@vger.kernel.org # v4.13
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/exynos/exynos_drm_drv.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -174,6 +174,7 @@ static int exynos_drm_suspend(struct dev
 	if (pm_runtime_suspended(dev) || !drm_dev)
 		return 0;
 
+	drm_modeset_lock_all(drm_dev);
 	drm_connector_list_iter_begin(drm_dev, &conn_iter);
 	drm_for_each_connector_iter(connector, &conn_iter) {
 		int old_dpms = connector->dpms;
@@ -185,6 +186,7 @@ static int exynos_drm_suspend(struct dev
 		connector->dpms = old_dpms;
 	}
 	drm_connector_list_iter_end(&conn_iter);
+	drm_modeset_unlock_all(drm_dev);
 
 	return 0;
 }
@@ -198,6 +200,7 @@ static int exynos_drm_resume(struct devi
 	if (pm_runtime_suspended(dev) || !drm_dev)
 		return 0;
 
+	drm_modeset_lock_all(drm_dev);
 	drm_connector_list_iter_begin(drm_dev, &conn_iter);
 	drm_for_each_connector_iter(connector, &conn_iter) {
 		if (connector->funcs->dpms) {
@@ -208,6 +211,7 @@ static int exynos_drm_resume(struct devi
 		}
 	}
 	drm_connector_list_iter_end(&conn_iter);
+	drm_modeset_unlock_all(drm_dev);
 
 	return 0;
 }