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

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Date:	Tue, 16 Feb 2016 12:58:56 +0200
From:	Oleksandr Natalenko <oleksandr@...alenko.name>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
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

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
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!

===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?