drm/i915/crt: Explicitly return false if connected to a digital monitor

Rather than proceed on and silently return false by default, mention why
we rejected the presence of an EDID as implying the presence of a VGA
monitor. (The question arises whether there is a broken EDID which falsely
reports a digital connection when attached by VGA.)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index e93f93cc7e78..0979d8877880 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -288,6 +288,8 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector)
                  * This may be a DVI-I connector with a shared DDC
                  * link between analog and digital outputs, so we
                  * have to check the EDID input spec of the attached device.
+                 *
+                 * On the other hand, what should we do if it is a broken EDID?
                  */
                 if (edid != NULL) {
                         is_digital = edid->input & DRM_EDID_INPUT_DIGITAL;
@@ -298,6 +300,8 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector)
                 if (!is_digital) {
                         DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
                         return true;
+                } else {
+                        DRM_DEBUG_KMS("CRT not detected via DDC:0x50 [EDID reports a digital panel]\n");
                 }
         }