drm/i915/gt: Only ignore rc6 parking for PCU on byt/bsw

An oversight in that we use rc6->ctl_enable to disable rc6 on gen9 and
so it does not simply indicate indirect control via a PCU. Switch the
rc6->ctl_enable check for a platform-based check.

Fixes: 972745fd ("drm/i915/gt: Disable manual rc6 for Braswell/Baytrail")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191212072737.884335-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_rc6.c

@@ -576,6 +576,7 @@ void intel_rc6_enable(struct intel_rc6 *rc6)
 	else if (INTEL_GEN(i915) >= 6)
 		gen6_rc6_enable(rc6);
 
+	rc6->manual = rc6->ctl_enable & GEN6_RC_CTL_RC6_ENABLE;
 	if (NEEDS_RC6_CTX_CORRUPTION_WA(i915))
 		rc6->ctl_enable = 0;
 
@@ -612,7 +613,7 @@ void intel_rc6_park(struct intel_rc6 *rc6)
 		return;
 	}
 
-	if (!(rc6->ctl_enable & GEN6_RC_CTL_RC6_ENABLE))
+	if (!rc6->manual)
 		return;
 
 	/* Turn off the HW timers and go directly to rc6 */

drivers/gpu/drm/i915/gt/intel_rc6_types.h

@@ -24,6 +24,7 @@ struct intel_rc6 {
 
 	bool supported : 1;
 	bool enabled : 1;
+	bool manual : 1;
 	bool wakeref : 1;
 };