From c2fde23d77ebcf4577fdd703af8b1600f3c87f69 Mon Sep 17 00:00:00 2001 From: David Müller Date: Fri, 19 Apr 2013 10:41:50 +0200 Subject: drm/i915: Fall back to bit banging mode for DVO transmitter detection MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit e4bfff54ed3f5de88f5358504c78c2cb037813aa upstream. As discussed in this thread http://lists.freedesktop.org/archives/dri-devel/2013-April/037411.html GMBUS based DVO transmitter detection seems to be unreliable which could result in an unusable DVO port. The attached patch fixes this by falling back to bit banging mode for the time DVO transmitter detection is in progress. Signed-off-by: David Müller Tested-by: David Müller Signed-off-by: Daniel Vetter Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/intel_dvo.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c index 6eda1b51c63..8ac91b80e15 100644 --- a/drivers/gpu/drm/i915/intel_dvo.c +++ b/drivers/gpu/drm/i915/intel_dvo.c @@ -371,6 +371,7 @@ void intel_dvo_init(struct drm_device *dev) const struct intel_dvo_device *dvo = &intel_dvo_devices[i]; struct i2c_adapter *i2c; int gpio; + bool dvoinit; /* Allow the I2C driver info to specify the GPIO to be used in * special cases, but otherwise default to what's defined @@ -390,7 +391,17 @@ void intel_dvo_init(struct drm_device *dev) i2c = &dev_priv->gmbus[gpio].adapter; intel_dvo->dev = *dvo; - if (!dvo->dev_ops->init(&intel_dvo->dev, i2c)) + + /* GMBUS NAK handling seems to be unstable, hence let the + * transmitter detection run in bit banging mode for now. + */ + intel_gmbus_force_bit(i2c, true); + + dvoinit = dvo->dev_ops->init(&intel_dvo->dev, i2c); + + intel_gmbus_force_bit(i2c, false); + + if (!dvoinit) continue; intel_encoder->type = INTEL_OUTPUT_DVO; -- cgit v1.2.3-18-g5258