On Sun, Jun 8, 2008 at 10:20 AM, Jean Delvare [off-list ref] wrote:

On Fri, 06 Jun 2008 23:50:18 +1000, Benjamin Herrenschmidt wrote:

quoted

On Fri, 2008-06-06 at 12:01 +0200, Jean Delvare wrote:

quoted

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.

There are 4 or 5 ddc buses (really just gpios) and each oem can choose
to wire up to a connector.  The bios connector table contains this
map.  ddc_vga and ddc_dvi are the most commonly used, but I've seen
cards with other settings.  If you want the full story take a look at
the xorg radeon driver (xf86-video-ati).

quoted

                                                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.

They are just gpio pads.  All the cards supported by radeonfb have
then, but only certain ones are wired up as per the bios connector
tables on x86 cards.  Mac cards and we currently hard code them based
on lots of investigation.  I suppose, ideally, you check the connector
tables and some of the other bios tables (powerplay, external tmds,
ext dac, multimedia. etc.) and only init the buses you have a
particular card.

Alex

Thanks,
--
Jean Delvare

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