Hello
Since Linux 2.6.36 the digital output on my system (855GME + DVI-I) is
not working any longer. The analog output is always activated regardless
of the type of monitor attached.
The culprit seems to be intel_crt_detect_ddc(), which returns true as
soon as an ACK from the EDID device is received. Obviously this approach
does not work with DVI-I where the analog and digital outputs share a
common DDC bus.
The patch below adds an additional check to make sure that there is
really an analog device attached (similar to the "Mac mini hack" in
intel_sdvo.c)
Signed-off-by: David Müller <d.muel...@elsoft.ch>
diff -dpurN a/drivers/gpu/drm/i915/intel_crt.c
b/drivers/gpu/drm/i915/intel_crt.c
--- a/drivers/gpu/drm/i915/intel_crt.c 2011-01-05 10:35:18.449000023 +0100
+++ b/drivers/gpu/drm/i915/intel_crt.c 2011-01-06 12:16:47.630998952 +0100
@@ -30,6 +30,7 @@
#include "drm.h"
#include "drm_crtc.h"
#include "drm_crtc_helper.h"
+#include "drm_edid.h"
#include "intel_drv.h"
#include "i915_drm.h"
#include "i915_drv.h"
@@ -287,8 +288,9 @@ static bool intel_crt_ddc_probe(struct d
return i2c_transfer(&dev_priv->gmbus[ddc_bus].adapter, msgs, 1) == 1;
}
-static bool intel_crt_detect_ddc(struct intel_crt *crt)
+static bool intel_crt_detect_ddc(struct drm_connector *connector)
{
+ struct intel_crt *crt = intel_attached_crt(connector);
struct drm_i915_private *dev_priv = crt->base.base.dev->dev_private;
/* CRT should always be at 0, but check anyway */
@@ -301,8 +303,26 @@ static bool intel_crt_detect_ddc(struct
}
if (intel_ddc_probe(&crt->base, dev_priv->crt_ddc_pin)) {
- DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
- return true;
+ struct edid *edid;
+ bool is_digital = false;
+
+ edid = drm_get_edid(connector,
+ &dev_priv->gmbus[dev_priv->crt_ddc_pin].adapter);
+ /*
+ * This may be a DVI-I connector with a shared DDC
+ * link between analog and digital outputs, so we
+ * have to check the EDID input spec of the attached device.
+ */
+ if (edid != NULL) {
+ is_digital = edid->input & DRM_EDID_INPUT_DIGITAL;
+ connector->display_info.raw_edid = NULL;
+ kfree(edid);
+ }
+
+ if (!is_digital) {
+ DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
+ return true;
+ }
}
return false;
@@ -458,7 +478,7 @@ intel_crt_detect(struct drm_connector *c
}
}
- if (intel_crt_detect_ddc(crt))
+ if (intel_crt_detect_ddc(connector))
return connector_status_connected;
if (!force)
@@ -472,7 +492,7 @@ intel_crt_detect(struct drm_connector *c
crtc = intel_get_load_detect_pipe(&crt->base, connector,
NULL, &dpms_mode);
if (crtc) {
- if (intel_crt_detect_ddc(crt))
+ if (intel_crt_detect_ddc(connector))
status = connector_status_connected;
else
status = intel_crt_load_detect(crtc, crt);
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