Re: radeonfb monid i2c bus

[Jean Delvare <khali@linux-fr.org>]

On Fri, 06 Jun 2008 23:50:18 +1000, Benjamin Herrenschmidt wrote:
> On Fri, 2008-06-06 at 12:01 +0200, Jean Delvare wrote:
> > Can you explain what is the "monid" i2c bus on Radeon adapters? I have
> > two Radeon chips here, an M6 in my old laptop and a 9200 in my desktop
> > system. On the M6 there is nothing on the monid bus. On the 9200, the
> > monid bus doesn't even work, every access results in timeout. The
> > radeonfb driver doesn't even look for EDID EEPROMs on that bus (except
> > in debug code.)
> > 
> > So I'm curious why you create this i2c bus if you don't need it.
> > Have you ever seen a Radeon adapter where there is something on that
> > bus?
> 
> The BIOS connector tables might make us use it.

Where is the code handling this? In radeon_monitor.c I can only see
radeon_probe_i2c_connector() being called on ddc_vga, ddc_dvi and
ddc_crt2. No reference to ddc_monid.

>                                                 Otherwise, it tends to
> have the external TMDS transmitter on it for which we'll one day get
> proper support for re-initializing on wakeup from sleep...

But apparently not all chips have the "monid" bus? Or is it a card
property, and other cards using the same Radeon 9200 might have it
while mine doesn't? I wouldn't care about an empty i2c bus, but a
broken bus as I get now affects the whole i2c subsystem and its users
in unpleasant ways. That's why I am wondering if there's a way to avoid
it.

Thanks,
-- 
Jean Delvare

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