Ilia Mirkin <[email protected]> [Mi, 05.03.2014 15:39]:
> On Wed, Mar 5, 2014 at 2:57 PM, Nils Krafft <[email protected]> wrote:
> > Hi,
> >
> > Ilia Mirkin <[email protected]> [Mi, 05.03.2014 12:46]:
> >> On Wed, Mar 5, 2014 at 6:06 AM, Dirk Thierbach <[email protected]> wrote:
> >> > On Wed, Mar 05, 2014 at 12:40:34AM -0500, Ilia Mirkin wrote:
> >> >> On Mon, Mar 3, 2014 at 5:41 PM, Nils Krafft <[email protected]> 
> >> >> wrote:
> >> >> > I have here a GeForce 2MX (NV10) with a Brooktree BT869 chip for the
> >> >> > TV-Out.
> >> >
> >> > You can try nvtv (http://sourceforge.net/projects/nv-tv-out/). It 
> >> > bypasses
> >> > X and modesetting and programs the Brooktree and CRTC directly. I've
> >> > no idea if it still work with modern X and/or nouveau. :-)
> >> >
> >> >> > shows me only the DVI connection (in fact it's VGA, not DVI), but not
> >> >> > the S-Video connection. If not supported, is this planned for future
> >> >> > versions?
> >> >
> >> >> The relevant hardware is not easily available, nor is hardware to
> >> >> consume s-video/composite connections.
> >> >
> >> > I still have some hardware for both, though I haven't used it for a long
> >> > time.
> >> >
> >> >> This sort of thing is probably
> >> >> only going to be supported if you make it happen. If you're
> >> >> interested, the relevant source file is
> >> >> drivers/gpu/drm/nouveau/dispnv04/tvnv04.c, and you'd have to add
> >> >> something in drivers/gpu/drm/i2c. BT* chips are usually easy to find
> >> >> docs for, and some of the additional details can probably be worked
> >> >> out from mmiotraces, assuming you can find a kernel that the blob
> >> >> driver will load on.
> >> >
> >> > It's much better to work from the datasheet instead of doing mmiotraces,
> >> > the blob only has a few modes built-in.
> >> >
> >> > The BT is actually a very flexible chip, and supports a very wide range
> >> > of modes with different overscan amount, plus different filtering 
> >> > options.
> >> >
> >> > It probably wouldn't be hard to just take a few modes from nvtv and
> >> > put them into nouveau, similar to the (very few) Chrontel modes. What's
> >> > missing is some sort of infrastructure in X to say "look, on this 
> >> > hardware
> >> > there are these two functional blocks (CRTC + BT), I would like to 
> >> > program
> >> > with the following values, and I've specified the values in the config
> >> > file, or I'm a user space program and provide these values over some X
> >> > extension".
> >> >
> >> > This is even more effort now that modesetting is in the kernel (back
> >> > when nvtv was written, it wasn't).
> >> >
> >> > Without this, you are pretty much stuck with precalculated modes.
> >> > Which isn't optimal, because with small overscan the timing gets a bit
> >> > fickle, and with larger overscan you get the ugly border, and every
> >> > analog TV is different in that respect.
> >>
> >> I actually checked this out last night, grabbed the BT869 datasheet.
> >> Basically you'd have to implement something similar to the ch7006
> >> driver (see drivers/gpu/drm/i2c), which provides an API for setting
> >> modes (the BT869 appears to have 8 of them, of which I'm guessing only
> >> 4 are actually usable, probably the RGB ones). Then you'd need to work
> >> out what the I2C index of it is, which you can tell by checking the
> >> VBIOS. Of course, this all requires the relevant hardware.
> >>
> >> The stuff about overscan/etc are exposed as KMS properties (which in
> >> turn appear in xrandr) and not specific to the BT869. The i2c driver
> >> is supposed to expose a ->mode_set() function, which takes a
> >> drm_display_mode.
> >>
> >>   -ilia
> >>
> >
> > Meanwhile I fiddled about with nvtv and found out that it still works
> > fine. The trick is that I have to switch the X-server to the desired
> > TV-Out resolution before activating the TV-Out, otherwise the X-server
> > freezes.
> 
> Great! I'll put that up as a workaround on the wiki, should be enough
> to get people going.
> 
> >
> > Doing the TV-Out via xrandr and Xinerama would be much more
> > comfortable, but I understand that nowadays (with HDMI and such stuff)
> > S-Video is nearly a "dead horse", so it obviously does not make much
> > sense to spend great efforts here. But if anyone with sufficient
> > knowledge (i. e. not me...) has enough spare time and feels like doing
> > this, I would really appreciate it :-)
> 
> If you're willing to test stuff (i.e. compile nouveau modules, load
> them, check that they work), I'll throw it on the todo list. The
> problem with this hw is finding someone who can test. (But even if you
> are willing, I don't want to provide false expectations -- it's
> reasonably likely that no one will take this work on.)
> 
> Cheers,
> 
>   -ilia

Yes, I am willing to do tests if someone wants to do that work, no
problem. And I fully understand that this has very low priority for
the developers...

Please keep me in Cc regarding this subject if possible, I'm not
subscribed.


Thanks,
Nils
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