[Intel-gfx] [PATCH 16/29] drm/i915: detect PCH encoders on Haswell

[Eugeni Dodonov]

On Haswell, the only PCH-connected output is the one driven by DDI E in
FDI mode, used for VGA connection. All the others are handled by the CPU.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e4ebd39..b01afb0 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3098,6 +3098,13 @@ static bool intel_crtc_driving_pch(struct drm_crtc *crtc)
 		if (encoder->base.crtc != crtc)
 			continue;
 
+		/* On Haswell, only DDI E can connect to PCH through FDI to drive VGA */
+		if (IS_HASWELL(dev) && (encoder->type != DRM_MODE_ENCODER_DAC)) {
+			DRM_DEBUG_KMS("Non-PCH encoder detected on Haswell. Allowed: %d, detected: %d\n",
+					DRM_MODE_ENCODER_DAC, encoder->type);
+			return false;
+		}
+
 		switch (encoder->type) {
 		case INTEL_OUTPUT_EDP:
 			if (!intel_encoder_is_pch_edp(&encoder->base))
-- 
1.7.10