On Haswell, the recommended 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.
Note that this does not accounts for Haswell/PPT combination yet, so if we
encounter such combination an error message is thrown to indicate that
things could go wrong.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f809d6a..96933cc 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2610,6 +2610,22 @@ static bool intel_crtc_driving_pch(struct drm_crtc *crtc)
if (encoder->base.crtc != crtc)
continue;
+ /* On Haswell, LPT PCH handles the VGA connection via FDI, and Haswell
+ * CPU handles all others */
+ if (IS_HASWELL(dev)) {
+ if (encoder->type == DRM_MODE_ENCODER_DAC) {
+ /* It is still unclear how this would work on PPT, so throw up an error */
+ if (!HAS_PCH_LPT(dev))
+ DRM_ERROR("DAC detected on a non-LPT PCH, this probably won't work\n");
+
+ return true;
+ } else {
+ DRM_DEBUG_KMS("Haswell detected encoder %d, assuming is CPU\n",
+ encoder->type);
+ return false;
+ }
+ }
+
switch (encoder->type) {
case INTEL_OUTPUT_EDP:
if (!intel_encoder_is_pch_edp(&encoder->base))
--
1.7.10
