linux-kernel - Re: [REGRESSION] i915: No HDMI output with 4.4

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Message-ID: <20160223150800.GK23290@intel.com>
Date:	Tue, 23 Feb 2016 17:08:00 +0200
From:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:	Oleksandr Natalenko <oleksandr@...alenko.name>
Cc:	Daniel Vetter <daniel.vetter@...el.com>,
	intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Sonika Jindal <sonika.jindal@...el.com>,
	Shashank Sharma <shashank.sharma@...el.com>,
	Gary Wang <gary.c.wang@...el.com>
Subject: Re: [REGRESSION] i915: No HDMI output with 4.4

On Mon, Feb 22, 2016 at 02:32:32PM +0200, Oleksandr Natalenko wrote:
> Ville, Daniel,
> 
> any additional info I could provide? I have to return dual-link DVI 
> cable back, so let me know if I could reveal more details if necessary.

Unfortunately I'm out of ideas for now. Daniel is on vacation.
Anyone else? VPG folks should take the ball here since they broke it.

In the meantime I think as a workaround I think you could use
something like video=HDMI-A-1:e on the kernel command line (not sure
I got the connector name right for your system). I think that should
result in the live status check to be skipped, at least when
populating the mode list.

Might be a good idea to collect all the information here and put in a
bug report (https://bugs.freedesktop.org/ -> DRI -> DRM/Intel) so that
all the logs and such would be in one place.

> 
> Regards,
>    Oleksandr
> 
> 16.02.2016 14:54, Daniel Vetter написав:
> > On Tue, Feb 16, 2016 at 12:58:56PM +0200, Oleksandr Natalenko wrote:
> >> Ville, Daniel,
> >> 
> >> I've just got another monitor and another DVI-HDMI cable, and here 
> >> what I've
> >> got.
> >> 
> >> ===Single Link DVI-D cable with 3 different monitors===
> >> 
> >> Computer DVI ——— DVI-D (Single Link)/HDMI cable ——— HDMI LG 23MP65HQ-P 
> >> ===
> >> not working
> > 
> > I presume the above LG screen is what you've called previously "old
> > monitor"?
> > 
> >> Computer DVI ——— DVI-D (Single Link)/HDMI cable ——— HDMI LG 23MP67HQ-P 
> >> ===
> >> not working
> >> Computer DVI ——— DVI-D (Single Link)/HDMI cable ——— HDMI LG 23MP55HQ-P 
> >> ===
> >> works!
> >> 
> >> ===Dual Link DVI-D cable with monitor that doesn't work with Single 
> >> Link
> >> cable===
> >> 
> >> Computer DVI ——— DVI-D (Dual Link)/HDMI cable ——— HDMI LG 23MP65HQ-P 
> >> ===
> >> works!
> > 
> > Funky. Can you pls grab the debug logs (with the special patches from
> > Ville) for this case? I wonder why suddenly different cable and it 
> > works.
> > 
> > Also: Is this one of these older-ish screens where you must have a
> > dual-link cable to drive it at full resolution&refresh rate?
> > -Daniel
> > 
> > 
> >> ===Laptop with HDMI output===
> >> 
> >> Laptop HDMI ——— HDMI/HDMI cable ——— HDMI LG 23MP65HQ-P === works!
> >> 
> >> I'd say that single link DVI cables are broken with new kernel, but 
> >> one of
> >> monitors could work with such a cable. So I have no idea :(.
> >> 
> >> Regards,
> >>   Oleksandr.
> >> 
> >> 15.02.2016 17:42, Daniel Vetter wrote:
> >> >The other downside is that it'll make us non-compliant, which was the
> >> >point of this entire ordeal: HDMI spec forbids us from starting any i2c
> >> >transactions when the hpd isn't signalling a present screen.
> >> >
> >> >So maybe we need to buy one of these broken screens.
> >> >
> >> >Oleksandr, what exact model are you using? And any chance that you could
> >> >test this on some other machine with intel gfx and latest kernel, just to
> >> >make sure this really is some issue with the sink and not with the machine
> >> >itself? And I guess you've tested with some other hdmi sink, and that
> >> >works?

-- 
Ville Syrjälä
Intel OTC