drm/i915/crt: Use a DDC probe on 0xA0 before load-detect
The BIOS writer's guide suggests that a VGA connection will ACK a write to address 0xA0 and that this should be used before doing legacy load-detection. Considering the extreme cost of load-detection, performing an extra DDC seems a risk worth taking. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
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@ -261,6 +261,21 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
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return ret;
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}
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static bool intel_crt_ddc_probe(struct drm_i915_private *dev_priv, int ddc_bus)
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{
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u8 buf;
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struct i2c_msg msgs[] = {
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{
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.addr = 0xA0,
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.flags = 0,
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.len = 1,
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.buf = &buf,
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},
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};
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/* DDC monitor detect: Does it ACK a write to 0xA0? */
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return i2c_transfer(&dev_priv->gmbus[ddc_bus].adapter, msgs, 1) == 1;
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}
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static bool intel_crt_detect_ddc(struct drm_encoder *encoder)
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{
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struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
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@ -270,7 +285,17 @@ static bool intel_crt_detect_ddc(struct drm_encoder *encoder)
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if (intel_encoder->type != INTEL_OUTPUT_ANALOG)
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return false;
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return intel_ddc_probe(intel_encoder, dev_priv->crt_ddc_pin);
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if (intel_crt_ddc_probe(dev_priv, dev_priv->crt_ddc_pin)) {
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DRM_DEBUG_KMS("CRT detected via DDC:0xa0\n");
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return true;
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}
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if (intel_ddc_probe(intel_encoder, dev_priv->crt_ddc_pin)) {
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DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
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return true;
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}
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return false;
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}
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static enum drm_connector_status
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@ -296,6 +321,8 @@ intel_crt_load_detect(struct drm_crtc *crtc, struct intel_encoder *intel_encoder
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uint8_t st00;
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enum drm_connector_status status;
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DRM_DEBUG_KMS("starting load-detect on CRT\n");
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if (pipe == 0) {
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bclrpat_reg = BCLRPAT_A;
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vtotal_reg = VTOTAL_A;
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@ -412,9 +439,10 @@ intel_crt_detect(struct drm_connector *connector, bool force)
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enum drm_connector_status status;
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if (I915_HAS_HOTPLUG(dev)) {
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if (intel_crt_detect_hotplug(connector))
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if (intel_crt_detect_hotplug(connector)) {
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DRM_DEBUG_KMS("CRT detected via hotplug\n");
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return connector_status_connected;
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else
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} else
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return connector_status_disconnected;
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}
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@ -431,7 +459,10 @@ intel_crt_detect(struct drm_connector *connector, bool force)
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crtc = intel_get_load_detect_pipe(encoder, connector,
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NULL, &dpms_mode);
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if (crtc) {
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status = intel_crt_load_detect(crtc, encoder);
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if (intel_crt_detect_ddc(&encoder->base))
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status = connector_status_connected;
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else
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status = intel_crt_load_detect(crtc, encoder);
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intel_release_load_detect_pipe(encoder,
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connector, dpms_mode);
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} else
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