[Intel-gfx] [PATCH] drm/i915: get a runtime PM ref in i915_wedged_set

[Michel Thierry]

At least in bxt (with decoupled mmio), it prevents a warning while
capturing the reg state:

 [  ] WARNING: assert_rpm_wakelock_held.part.4+0x1e/0x20 [i915]
 [  ] RPM wakelock ref not held during HW access
 [  ] Call Trace:
 [  ]  dump_stack+0x63/0x87
 [  ]  __warn+0xd1/0xf0
 [  ]  ? fwtable_write32+0x1a0/0x1a0 [i915]
 [  ]  warn_slowpath_fmt+0x4f/0x60
 [  ]  ? vprintk_default+0x29/0x50
 [  ]  assert_rpm_wakelock_held.part.4+0x1e/0x20 [i915]
 [  ]  gen9_decoupled_read32+0x18a/0x1a0 [i915]
 [  ]  ? fwtable_write32+0x1a0/0x1a0 [i915]
 [  ]  i915_handle_error+0x1d0/0x260 [i915]
 [  ]  ? __check_object_size+0x170/0x1aa
 [  ]  i915_wedged_set+0x25/0x30 [i915]

These get/put were removed by commit 9c870d03674f ("drm/i915: Use RPM as the
barrier for controlling user mmap access"), before decoupled mmio was
added in commit 85ee17ebeedd ("drm/i915/bxt: Broxton decoupled MMIO).

Reported-by: Antonio Argenziano <antonio.argenziano at intel.com>
Signed-off-by: Michel Thierry <michel.thierry at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 9fcc4f1a86fc..89f211391ef9 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4155,9 +4155,13 @@ i915_wedged_set(void *data, u64 val)
 	if (i915_reset_in_progress(&dev_priv->gpu_error))
 		return -EAGAIN;
 
+	intel_runtime_pm_get(dev_priv);
+
 	i915_handle_error(dev_priv, val,
 			  "Manually setting wedged to %llu", val);
 
+	intel_runtime_pm_put(dev_priv);
+
 	return 0;
 }
 
-- 
2.11.0