[Intel-gfx] [PATCH] drm/i915: reinstate GM45 TV detection fix

Peter Clifton peter.clifton at clifton-electronics.co.uk
Tue Mar 27 13:03:29 CEST 2012

On Mon, 2012-03-26 at 15:57 -0300, Rodrigo Vivi wrote:
> The GM45 with tv-out is so rare machine that I never found one to test
> if this really cause regression and complete disable tv-out on gm45 so
> I'm in favor of apply this and when we find some one with gm45
> complaining about the tv-out not working we will be able to
> test/revert and find another fix for it. Meanwhile:
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>

Tested-by: Peter Clifton <Peter.Clifton at clifton-electronics.com>

I've been carrying that patch around in my own builds for my GM45 for
what feels like forever now (since before it was reverted... I helped
identify the requirement, by trial and error in the first place!).

For further details, you might like to contact the guy at Intel who
wrote the commit: ykzhao <yakui.zhao at intel.com>

>From some correspondence we had...


> > > Yes. This is not consistent with the description on PRM. 
> > > But this is required on Cantiga platform to make the TV detection
> > > reliable.
> > 
> > Thanks Zhau,


> > Hopefully we'll be able to get the patch re-committed to the
> kernel. 
> > 
> > Since the main issue with the patch was comments as to why this is a
> > good thing to do on GM45, would you be willing to create a new patch
> > with some code-comments (and commit message) explaining the source
> of
> > the correction?
> > 
> > (Are there any comments from the BIOS code as to why these registers
> > need to be programmed in a particular way?)


> Sorry that there is no comment in BIOS code. BIOS team only tells me
> to follow the BIOS code but there is no explanation about the reason.


> > If you like, I could take your original patch and try to add some
> > comments along the lines of what you just explained, then re-send it
> > to intel-gfx for review.

Oops... I never got around to this.

I'd love to see it fixed though, but am too busy to chase it myself now.

Kind regards,

Peter Clifton <peter.clifton at clifton-electronics.co.uk>

Clifton Electronics

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