[Intel-gfx] [PATCH v2 02/10] drm/i915: Don't register CRT connector when DDI E can't be used

ville.syrjala at linux.intel.com ville.syrjala at linux.intel.com
Tue Dec 1 13:29:56 PST 2015

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

On HSW/BDW DDI A and E share 2 lanes, so when DDI A requires the
shared lanes DDI E can't be used. The lanes are not supposed to
be dynamically switched between the two uses, so there's no point
in registering the CRT connector when DDI E has no lanes.

v2: Fix typos in the commit message (Paulo)

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
 drivers/gpu/drm/i915/intel_display.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index bfb00e383587..0ce988af1300 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14260,6 +14260,10 @@ static bool intel_crt_present(struct drm_device *dev)
 		return false;
+	/* DDI E can't be used if DDI A requires 4 lanes */
+	if (HAS_DDI(dev) && I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_A_4_LANES)
+		return false;
 	if (IS_VALLEYVIEW(dev) && !dev_priv->vbt.int_crt_support)
 		return false;

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