Patch "drm/bridge: analogix dp: Fix runtime PM state on driver bind" has been added to the 4.9-stable tree

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

drm/bridge: analogix dp: Fix runtime PM state on driver bind

to the 4.9-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-bridge-analogix-dp-fix-runtime-pm-state-on-driver-bind.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Marek Szyprowski <[email protected]>
Date: Fri, 30 Dec 2016 10:57:46 +0100
Subject: drm/bridge: analogix dp: Fix runtime PM state on driver bind

From: Marek Szyprowski <[email protected]>

commit f0a8b49c03d22a511a601dc54b2a3425a41e35fa upstream.

Analogix_dp_bind() can be called from component framework, which doesn't guarantee proper runtime PM state of the device during bind operation, so ensure that device is runtime active before doing any register access. This ensures that the power domain, to which DP module belongs, is turned on. While at it, also fix the unbalanced call to phy_power_on() in analogix_dp_bind() function.

This patch solves the following kernel oops on Samsung Exynos5250 Snow board:

Unhandled fault: imprecise external abort (0x406) at 0x00000000 pgd = c0004000
[00000000] *pgd=00000000

Internal error: : 406 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 75 Comm: kworker/0:2 Not tainted 4.9.0 #1046
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
Workqueue: events deferred_probe_work_func

task: ee272300 task.stack: ee312000
PC is at analogix_dp_enable_sw_function+0x18/0x2c
LR is at analogix_dp_init_dp+0x2c/0x50
...
[<c03fcb38>] (analogix_dp_enable_sw_function) from [<c03fa9c4>] (analogix_dp_init_dp+0x2c/0x50) [<c03fa9c4>] (analogix_dp_init_dp) from [<c03fab6c>] (analogix_dp_bind+0x184/0x42c) [<c03fab6c>] (analogix_dp_bind) from [<c03fdb84>] (component_bind_all+0xf0/0x218) [<c03fdb84>] (component_bind_all) from [<c03ed64c>] (exynos_drm_load+0x134/0x200) [<c03ed64c>] (exynos_drm_load) from [<c03d5058>] (drm_dev_register+0xa0/0xd0) [<c03d5058>] (drm_dev_register) from [<c03d66b8>] (drm_platform_init+0x58/0xb0) [<c03d66b8>] (drm_platform_init) from [<c03fe0c4>] (try_to_bring_up_master+0x14c/0x188) [<c03fe0c4>] (try_to_bring_up_master) from [<c03fe188>] (component_add+0x88/0x138) [<c03fe188>] (component_add) from [<c0403a38>] (platform_drv_probe+0x50/0xb0) [<c0403a38>] (platform_drv_probe) from [<c0402470>] (driver_probe_device+0x1f0/0x2a8) [<c0402470>] (driver_probe_device) from [<c0400a54>] (bus_for_each_drv+0x44/0x8c) [<c0400a54>] (bus_for_each_drv) from [<c04021f8>] (__device_attach+0x9c/0x100) [<c04021f8>] (__device_attach) from [<c04018e8>] (bus_probe_device+0x84/0x8c) [<c04018e8>] (bus_probe_device) from [<c0401d1c>] (deferred_probe_work_func+0x60/0x8c) [<c0401d1c>] (deferred_probe_work_func) from [<c012fc14>] (process_one_work+0x120/0x318) [<c012fc14>] (process_one_work) from [<c012fe34>] (process_scheduled_works+0x28/0x38) [<c012fe34>] (process_scheduled_works) from [<c0130048>] (worker_thread+0x204/0x4ac) [<c0130048>] (worker_thread) from [<c01352c4>] (kthread+0xd8/0xf4)
[<c01352c4>] (kthread) from [<c0107978>] (ret_from_fork+0x14/0x3c)

Code: e59035f0 e5935018 f57ff04f e3c55001 (f57ff04e)
---[ end trace 3d1d0d87796de344 ]---

---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c |    7 +++++++
 1 file changed, 7 insertions(+)

@@ -1382,6 +1382,7 @@ int analogix_dp_bind(struct device *dev,
 
 	pm_runtime_enable(dev);
 
+	pm_runtime_get_sync(dev);
 	phy_power_on(dp->phy);
 
 	analogix_dp_init_dp(dp);

@@ -1414,9 +1415,15 @@ int analogix_dp_bind(struct device *dev,
 		goto err_disable_pm_runtime;
 	}
 
+	phy_power_off(dp->phy);
+	pm_runtime_put(dev);
+
 	return 0;
 
 err_disable_pm_runtime:
+
+	phy_power_off(dp->phy);
+	pm_runtime_put(dev);
 	pm_runtime_disable(dev);
 
 	return ret;

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

queue-4.9/drm-bridge-analogix-dp-fix-runtime-pm-state-on-driver-bind.patch