[Intel-gfx] [PATCH 1/2] drm/i915: Detect SDVO-RGB before SDVO TV

[Fu Michael]

Zhenyu Wang wrote:
> On 2010.01.30 09:38:16 +0800, Fu Michael wrote:
>   
>>> Why should what order the connectors get set up matter?  If it's supposed
>>> to matter, has this been tested in anything other than this guy's
>>> particular configuration to make sure that you're not regressing other
>>> picky encoders?
>>>
>>> If I had to take a wild guess, this would be another manifestation of
>>> the failure of the SDVO code to have a single encoder instance managing
>>> the multiple connectors attached to it, so the different connectors
>>> fight over the state of the encoder.
>>>   
>>>       
>> actually it's not the code but the card in this case.
>>
>>     
>
> well, we need to fix our code to work with that SDVO behaivor..
>
>   
actually "that SDVO behavior" is violating the SDVO spec. :)
>> we have only one way to know what kind of monitor is attached to a sDVO 
>> card, that is to send a command to it and read back response. For the 
>> card in this bug report, even though it only has VGA attached. It report 
>> all of its capabilities are connected, which apparently is not true. if 
>> we just pass that message up to user space, the bogus connection would 
>> mess up mode setting then, so technically, this is a patch in UMS that 
>> happen worked around it.
>>     
>
> In my origin patch for UMS on multifunction SDVO support, SDVO connector
> info is updated in output detect and output name for randr is given massage
> to adjust for real output type. For SDVO KMS, we should split encoder/connector
> state based on device capability, and detect would check if connector type
> matches.
>
>   
>> Such kind of multi-function sdvo card is rare. we don't have any, and we 
>> only see one bug report from community in our bugzilla as well.  I guess 
>> that's why UMS has been living with it fine for a long time.
>>
>>     
>
> UMS is fine with that as my note above. I think we do have a littlefall
> motherboard which has multi-function sdvo, that I used for SDVO TV enabling before.
>
>   
right. the Little Fall machine is a good citizen, even though it's a 
dual VGA/TV card too - It has TV output but never report VGA output as 
connected as well when only TV is connected...
>   
>>  I guess if we want a decent fix for this, maybe our last hope is to see 
>> if VBT has any information to tell us not to bother with other type but 
>> just one kind of connector on this SDVO device. But I'm not sure if this 
>> would break other normal cards then, just in case a VBT is broken...
>>     
>
> yeah, old platform usually won't have finally correct BIOS update.
>
>