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Commit f1a2f5b7 authored by Jani Nikula's avatar Jani Nikula Committed by Daniel Vetter
Browse files

drm/i915: fall back to bit-banging if GMBUS fails in CRT EDID reads 

GMBUS was enabled over bit-banging as the default in commits:

commit c3dfefa0
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Feb 14 22:37:25 2012 +0100

    drm/i915: reenable gmbus on gen3+ again

and

commit 0fb3f969
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Fri Mar 2 19:38:30 2012 +0100

    drm/i915: enable gmbus on gen2

Unfortunately, GMBUS seems to fail on some CRT displays. Add a bit-banging
fallback to CRT EDID reads.

LKML-Reference: <201207251020.47637.maciej.rutecki@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=45881


Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Tested-by: default avatarAlex Ferrando <alferpal@gmail.com>
Cc: stable@vger.kernel.org (for 3.4+3.5)
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 4eab8136

drivers/gpu/drm/i915/intel_crt.c

+33 −3
Original line number Diff line number Diff line
@@ -326,6 +326,36 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector) 
	return ret;

}



static struct edid *intel_crt_get_edid(struct drm_connector *connector,

				struct i2c_adapter *i2c)

{

	struct edid *edid;



	edid = drm_get_edid(connector, i2c);



	if (!edid && !intel_gmbus_is_forced_bit(i2c)) {

		DRM_DEBUG_KMS("CRT GMBUS EDID read failed, retry using GPIO bit-banging\n");

		intel_gmbus_force_bit(i2c, true);

		edid = drm_get_edid(connector, i2c);

		intel_gmbus_force_bit(i2c, false);

	}



	return edid;

}



/* local version of intel_ddc_get_modes() to use intel_crt_get_edid() */

static int intel_crt_ddc_get_modes(struct drm_connector *connector,

				struct i2c_adapter *adapter)

{

	struct edid *edid;



	edid = intel_crt_get_edid(connector, adapter);

	if (!edid)

		return 0;



	return intel_connector_update_modes(connector, edid);

}



static bool intel_crt_detect_ddc(struct drm_connector *connector)

{

	struct intel_crt *crt = intel_attached_crt(connector);
@@ -336,7 +366,7 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector) 
	BUG_ON(crt->base.type != INTEL_OUTPUT_ANALOG);



	i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->crt_ddc_pin);

	edid = drm_get_edid(connector, i2c);

	edid = intel_crt_get_edid(connector, i2c);



	if (edid) {

		bool is_digital = edid->input & DRM_EDID_INPUT_DIGITAL;
@@ -544,13 +574,13 @@ static int intel_crt_get_modes(struct drm_connector *connector) 
	struct i2c_adapter *i2c;



	i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->crt_ddc_pin);

	ret = intel_ddc_get_modes(connector, i2c);

	ret = intel_crt_ddc_get_modes(connector, i2c);

	if (ret || !IS_G4X(dev))

		return ret;



	/* Try to probe digital port for output in DVI-I -> VGA mode. */

	i2c = intel_gmbus_get_adapter(dev_priv, GMBUS_PORT_DPB);

	return intel_ddc_get_modes(connector, i2c);

	return intel_crt_ddc_get_modes(connector, i2c);

}



static int intel_crt_set_property(struct drm_connector *connector,