Mailinglist Archive: radeonhd (436 mails)

["Alex Deucher" <alexdeucher@xxxxxxxxx>]

On Tue, Jul 22, 2008 at 3:55 AM, Luc Verhaegen <libv@xxxxxxxxx> wrote:
> On Mon, Jul 21, 2008 at 06:20:17PM -0400, Alex Deucher wrote:
> > On Mon, Jul 21, 2008 at 6:07 PM, Sven Lankes <sven@xxxxxxx> wrote:
> > > On Mon, Jul 21, 2008 at 11:53:01PM +0200, Luc Verhaegen wrote:
> > >
> > > > > This looks like TMDSA load detection not working.
> > > > > Luc, can you look into this when you find the time?
> > >
> > > > You will find that, when you run rhd_conntest, the monitor only at
> > > > certain times puts loads on the digital lines. We have seen the same
> > > > problem with some other monitors...
> > >
> > > This is a Dell 24" - pretty common I'd say.
> > >
> > > > So it is a problem with not the TMDSA load detection, but with the
> > > > monitor attached to it, and a suitable strategy still needs to be
> > > > proposed here.
> > >
> > > Pardon my ignorance but how does the radeon-driver handle this?
> >
> > radeon uses ddc to detect the presence of a monitor, and then (for
> > DACs at least) falls back to load detection if ddc fails.
> >
> > Alex
>
> No, this is not the explanation. The real explanation is that radeon
> doesn't even try to implement load detection for TMDSA, even though the
> r5xx/r6xx hardware supports it nicely.

We don't use load detection for TMDS and if we did it would be a fall
back if ddc failed.  I agree that the hw supports it, (even pre-avivo
chips supported it to a certain extent), but the problem, as this
thread shows, is that it's not reliable.  I'm not saying ddc is
reliable either, but it seems to generally be more reliable than load
detection in my experience.

Alex
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