On Fri, Apr 19, 2013 at 10:41:50AM +0200, "David M?ller (ELSOFT AG)" wrote: > Hello > > 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 M?ller <d.mueller at elsoft.ch> > Tested-by: David M?ller <d.mueller at elsoft.ch> > > --- > diff -dpurN a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c > --- a/drivers/gpu/drm/i915/intel_dvo.c 2012-12-11 10:09:35.113446850 +0100 > +++ b/drivers/gpu/drm/i915/intel_dvo.c 2013-04-19 07:21:54.054546365 +0200 > @@ -449,6 +449,7 @@ void intel_dvo_init(struct drm_device *d > 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 > @@ -468,7 +469,17 @@ void intel_dvo_init(struct drm_device *d > i2c = intel_gmbus_get_adapter(dev_priv, gpio); > > 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); Shouldn't we keep the dvo i2c line in bit-banging mode always, i.e. restore gmbus mode only when dvo init failed? I suspect that for fickle hw not just init will fail ... -Daniel > + > + if (!dvoinit) > continue; > > intel_encoder->type = INTEL_OUTPUT_DVO; -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
