drm/i915/sdvo: Handle unsupported GET_SUPPORTED_ENHANCEMENTS gracefully

In the event that the external chipset doesn't implement the
GET_SUPPORTED_ENHANCEMENTS commands, gracefully treat it as having no
enhancments rather than bailing.

Reported-and-tested-by: Woody Suwalski <terraluna977@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=18342
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 60fcef7..ee73e42 100644 (file)
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -2520,11 +2520,10 @@ static bool intel_sdvo_create_enhance_property(struct intel_sdvo *intel_sdvo,
                uint16_t response;
        } enhancements;
 
-       if (!intel_sdvo_get_value(intel_sdvo,
-                                 SDVO_CMD_GET_SUPPORTED_ENHANCEMENTS,
-                                 &enhancements, sizeof(enhancements)))
-               return false;
-
+       enhancements.response = 0;
+       intel_sdvo_get_value(intel_sdvo,
+                            SDVO_CMD_GET_SUPPORTED_ENHANCEMENTS,
+                            &enhancements, sizeof(enhancements));
        if (enhancements.response == 0) {
                DRM_DEBUG_KMS("No enhancement is supported\n");
                return true;