Re: [PATCH 2/2] drm/radeon/kms: enable underscan option for digital connectors

["Marius Gröger" <marius.groeger@googlemail.com>]

Am 09.08.2010 09:33, wrote Alex Deucher:
> 2010/8/9 Marius Gröger<marius.groeger@googlemail.com>:
>> Am 08.08.2010 20:09, wrote Alex Deucher:
>>>
>>> 2010/8/8 Marius Gröger<marius.groeger@googlemail.com>:
>>>>
>>>> Am 08.08.2010 18:22, wrote Alex Deucher:
>>>>>>
>>>>>> Also, I kind of was hoping that once I could use 1280x720 for both the
>>>>>> console and the X screen, it would would allow me to switch between the
>>>>>> two
>>>>>> transparently. Instead, the TV takes notice of the switch and needs
>>>>>> some
>>>>>> extra syncing time. Is this expected behaviour?
>>>>>
>>>>> You mean switching underscan off and on or a VT switch?  The hw has to
>>>>> reprogram the mode when it changes the underscan.  As for a VT switch,
>>>>> it should just be changing the crtc base, but IIRC there was a bug
>>>>> where X and the console used slightly different modes in some cases.
>>>>
>>>> VT switch. I use video=1280x720@50 on the command line and select the
>>>> corresponding EDID resolution within X. Is this bug still pending or is
>>>> my
>>>> scenario supposed to work?
>>>
>>> You may be seeing this issue:
>>> http://lists.x.org/archives/xorg-devel/2010-August/011743.html
>>
>> "In the absence of the user specifying an overriding monitor
>> configuration, trust the KMS drivers to have correctly probed the output
>> modes."
>>
>> Well, in my case I *am* specifying an overriding monitor configuration. Is
>> there still a chance that video=1280x720@50 could be meaning s.th. different
>> then the corresponding mode in X that I explicitly choose.
>
> Can you verify that the console and X are using the same modeline?
> The mode selected by video=1280x720@50 likely has different timing
> than the timing used by the mode in X.  Is the VT switch smooth when
> you don't specify the mode on the console or X (i.e., let the driver
> decide on it's own)?

Ah ok, "likely has different timing" - this is probably the issue here. 
I'll be investigating this. Is there a way to influence the timing used 
by video=1280x720@50 to match the one used in X? Or should I try finding 
out about the console timing and use that as an xorg.conf modeline?

Regards
Marius