[PATCH v2 8/8] drm/i915: ensure correct VLV IOSF SB units have been get/put

[Jani Nikula]

Add some extra paranoia to check correct use of the VLV IOSF SB
get/put/read/write.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h    |  1 +
 drivers/gpu/drm/i915/vlv_iosf_sb.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d0e1980dcba2..93b4c504b710 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -230,6 +230,7 @@ struct drm_i915_private {
 	/* VLV/CHV IOSF sideband */
 	struct {
 		struct mutex lock; /* protect sideband access */
+		unsigned long locked_unit_mask;
 		struct pm_qos_request qos;
 	} vlv_iosf_sb;
 
diff --git a/drivers/gpu/drm/i915/vlv_iosf_sb.c b/drivers/gpu/drm/i915/vlv_iosf_sb.c
index c8f8589ee0be..f4b435555f3b 100644
--- a/drivers/gpu/drm/i915/vlv_iosf_sb.c
+++ b/drivers/gpu/drm/i915/vlv_iosf_sb.c
@@ -65,12 +65,18 @@ void vlv_iosf_sb_get(struct drm_device *drm, unsigned long unit_mask)
 		__vlv_punit_get(i915);
 
 	mutex_lock(&i915->vlv_iosf_sb.lock);
+
+	i915->vlv_iosf_sb.locked_unit_mask |= unit_mask;
 }
 
 void vlv_iosf_sb_put(struct drm_device *drm, unsigned long unit_mask)
 {
 	struct drm_i915_private *i915 = to_i915(drm);
 
+	i915->vlv_iosf_sb.locked_unit_mask &= ~unit_mask;
+
+	drm_WARN_ON(drm, i915->vlv_iosf_sb.locked_unit_mask);
+
 	mutex_unlock(&i915->vlv_iosf_sb.lock);
 
 	if (unit_mask & BIT(VLV_IOSF_SB_PUNIT))
@@ -182,6 +188,8 @@ u32 vlv_iosf_sb_read(struct drm_device *drm, enum vlv_iosf_sb_unit unit, u32 add
 	if (drm_WARN_ONCE(&i915->drm, !port, "invalid unit %d\n", unit))
 		return 0;
 
+	drm_WARN_ON(&i915->drm, !(i915->vlv_iosf_sb.locked_unit_mask & BIT(unit)));
+
 	vlv_sideband_rw(i915, devfn, port, opcode, addr, &val);
 
 	return val;
@@ -199,6 +207,8 @@ int vlv_iosf_sb_write(struct drm_device *drm, enum vlv_iosf_sb_unit unit, u32 ad
 	if (drm_WARN_ONCE(&i915->drm, !port, "invalid unit %d\n", unit))
 		return -EINVAL;
 
+	drm_WARN_ON(&i915->drm, !(i915->vlv_iosf_sb.locked_unit_mask & BIT(unit)));
+
 	return vlv_sideband_rw(i915, devfn, port, opcode, addr, &val);
 }
 
-- 
2.39.5