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drm/i915/crt: Use a DDC probe on 0xA0 before load-detect

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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>
This commit is contained in:
Chris Wilson 2010-09-22 18:17:01 +01:00
parent a5cad620b3
commit 6ec3d0c0e9
1 changed files with 35 additions and 4 deletions
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39
drivers/gpu/drm/i915/intel_crt.c
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@ -261,6 +261,21 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
return ret;
}
static bool intel_crt_ddc_probe(struct drm_i915_private *dev_priv, int ddc_bus)
{
u8 buf;
struct i2c_msg msgs[] = {
{
.addr = 0xA0,
.flags = 0,
.len = 1,
.buf = &buf,
},
};
/* DDC monitor detect: Does it ACK a write to 0xA0? */
return i2c_transfer(&dev_priv->gmbus[ddc_bus].adapter, msgs, 1) == 1;
}
static bool intel_crt_detect_ddc(struct drm_encoder *encoder)
{
struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
@ -270,7 +285,17 @@ static bool intel_crt_detect_ddc(struct drm_encoder *encoder)
if (intel_encoder->type != INTEL_OUTPUT_ANALOG)
return false;
return intel_ddc_probe(intel_encoder, dev_priv->crt_ddc_pin);
if (intel_crt_ddc_probe(dev_priv, dev_priv->crt_ddc_pin)) {
DRM_DEBUG_KMS("CRT detected via DDC:0xa0\n");
return true;
}
if (intel_ddc_probe(intel_encoder, dev_priv->crt_ddc_pin)) {
DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
return true;
}
return false;
}
static enum drm_connector_status
@ -296,6 +321,8 @@ intel_crt_load_detect(struct drm_crtc *crtc, struct intel_encoder *intel_encoder
uint8_t st00;
enum drm_connector_status status;
DRM_DEBUG_KMS("starting load-detect on CRT\n");
if (pipe == 0) {
bclrpat_reg = BCLRPAT_A;
vtotal_reg = VTOTAL_A;
@ -412,9 +439,10 @@ intel_crt_detect(struct drm_connector *connector, bool force)
enum drm_connector_status status;
if (I915_HAS_HOTPLUG(dev)) {
if (intel_crt_detect_hotplug(connector))
if (intel_crt_detect_hotplug(connector)) {
DRM_DEBUG_KMS("CRT detected via hotplug\n");
return connector_status_connected;
else
} else
return connector_status_disconnected;
}
@ -431,7 +459,10 @@ intel_crt_detect(struct drm_connector *connector, bool force)
crtc = intel_get_load_detect_pipe(encoder, connector,
NULL, &dpms_mode);
if (crtc) {
status = intel_crt_load_detect(crtc, encoder);
if (intel_crt_detect_ddc(&encoder->base))
status = connector_status_connected;
else
status = intel_crt_load_detect(crtc, encoder);
intel_release_load_detect_pipe(encoder,
connector, dpms_mode);
} else