[Intel-gfx] [PATCH] drm/i915/skl: Ensure HW is powered during DDB HW state readout

[Imre Deak]

The assumption when adding the intel_display_power_is_enabled() checks
was that if it returns success the power can't be turned off afterwards
during the HW access, which is guaranteed by modeset locks. This isn't
always true, so make sure we hold a dedicated reference for the time of
the access.

Spotted-by: Mika Kuoppala <mika.kuoppala at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93441
CC: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index b63cdb2..347d4df 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2851,7 +2851,10 @@ void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
 	memset(ddb, 0, sizeof(*ddb));
 
 	for_each_pipe(dev_priv, pipe) {
-		if (!intel_display_power_is_enabled(dev_priv, POWER_DOMAIN_PIPE(pipe)))
+		enum intel_display_power_domain power_domain;
+
+		power_domain = POWER_DOMAIN_PIPE(pipe);
+		if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
 			continue;
 
 		for_each_plane(dev_priv, pipe, plane) {
@@ -2863,6 +2866,8 @@ void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
 		val = I915_READ(CUR_BUF_CFG(pipe));
 		skl_ddb_entry_init_from_hw(&ddb->plane[pipe][PLANE_CURSOR],
 					   val);
+
+		intel_display_power_put(dev_priv, power_domain);
 	}
 }
 
-- 
2.5.0