Re: [DVO][PATCH] drm/i915: Fall back to bit banging mode for DVO transmitter detection

["\"David Müller (ELSOFT AG)\"" <d.mueller@elsoft.ch>]

Daniel Vetter wrote:
> On Fri, Apr 19, 2013 at 10:41:50AM +0200, "David Müller (ELSOFT AG)" wrote:
>> +		/* 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 ...

As far as i can tell, the critical part is the NAK handling.

Dave