[PATCH] drm/i915/alpm: Check for alpm support before accessing alpm register

[Animesh Manna]

Currently as EDP only support alpm and check for alpm support will
prevent DP connector to access alpm register.

Signed-off-by: Animesh Manna <animesh.ma...@intel.com>
---
 drivers/gpu/drm/i915/display/intel_alpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c 
b/drivers/gpu/drm/i915/display/intel_alpm.c
index 482dd192d47d..1bf08b80c23f 100644
--- a/drivers/gpu/drm/i915/display/intel_alpm.c
+++ b/drivers/gpu/drm/i915/display/intel_alpm.c
@@ -556,7 +556,7 @@ void intel_alpm_disable(struct intel_dp *intel_dp)
        struct intel_display *display = to_intel_display(intel_dp);
        enum transcoder cpu_transcoder = intel_dp->alpm_parameters.transcoder;
 
-       if (DISPLAY_VER(display) < 20)
+       if (DISPLAY_VER(display) < 20 || !intel_dp->alpm_dpcd)
                return;
 
        mutex_lock(&intel_dp->alpm_parameters.lock);
-- 
2.29.0