[Intel-gfx] [PATCH 3/4] drm/i915: Do not modifiy reserved bit in gens that do not have IPC

[José Roberto de Souza]

IPC was only added in SKL+(actually we don't even enable for SKL due
WA) so without this change, driver was writing to a reserved bit.

Also check for the WA in intel_init_ipc() to avoid further writes to
ipc_enabled.

Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d99e5fabe93c..b2328f7d277d 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6108,10 +6108,8 @@ void intel_enable_ipc(struct drm_i915_private *dev_priv)
 	u32 val;
 
 	/* Display WA #0477 WaDisableIPC: skl */
-	if (IS_SKYLAKE(dev_priv)) {
-		dev_priv->ipc_enabled = false;
+	if (!HAS_IPC(dev_priv) || IS_SKYLAKE(dev_priv))
 		return;
-	}
 
 	val = I915_READ(DISP_ARB_CTL2);
 
@@ -6126,7 +6124,9 @@ void intel_enable_ipc(struct drm_i915_private *dev_priv)
 void intel_init_ipc(struct drm_i915_private *dev_priv)
 {
 	dev_priv->ipc_enabled = false;
-	if (!HAS_IPC(dev_priv))
+
+	/* Display WA #0477 WaDisableIPC: skl */
+	if (!HAS_IPC(dev_priv) || IS_SKYLAKE(dev_priv))
 		return;
 
 	dev_priv->ipc_enabled = true;
-- 
2.19.0