Re: No HDMI output on AC100

[Marc Dietrich <marvin24-Mmb7MZpHnFY@public.gmane.org>]

On Saturday 08 June 2013 20:45:17 Stephen Warren wrote:
> On 06/08/2013 02:07 PM, Marc Dietrich wrote:
> > On Saturday 08 June 2013 18:05:52 Lucas Stach wrote:
> >> Am Samstag, den 08.06.2013, 16:21 +0200 schrieb Thomas Meyer:
> >>>> On Saturday 08 June 2013 10:33:55 Thomas Meyer wrote:
> >>>>> Kernel version: 3.10.0-0.rc4.git0.1.fc20.armv7hl
> >>>>> 
> >>>>> This is the latest Fedora ARM kernel. Config is available here:
> >>>>> http://pkgs.fedoraproject.org/cgit/kernel.git/tree/config-armv7
> >>>>> 
> >>>>> This is what I see in the kernel log:
> >>>>> 
> >>>>> $ dmesg |grep hdmi
> >>>>> [   33.403417] tegra-hdmi 54280000.hdmi: failed to get VDD regulator
> >>>>> [   33.403441] platform 54280000.hdmi: Driver tegra-hdmi requests
> >>>>> probe
> >>>>> 
> >>>>> any ideas?
> >>>> 
> >>>> is the regulator (tps6586x) build-in?
> >>> 
> >>> No, it's a module.
> >>> 
> >>>> The make everything a module path isn't
> >>>> well tested I guess.
> >> 
> >> It's not the problem here. The driver requests to be probed again and
> >> comes up once the regulator is there.
> >> 
> >> Though the pixel clock looks odd for a HD HDMI monitor. Try looking at
> >> the Xorg log to see what mode of your monitor get's chosen and why it
> >> fails.
> > 
> > I just checked myself. Found that tps6586x-regulator module can't be
> > autoloaded, so I connected my TV, booted and modprobed the module by hand.
> > All works more or less fine, so probe deferral is no problem.
> 
> It could well just be that the tps6586x driver is missing the module
> correct MODULE_ALIAS that makes the module auto-load when the relevant
> entry is in the DT. The top-level MFD driver does have a
> MODULE_DEVICE_TABLE which should set this up automatically, so perhaps
> it's because there's nothing causing the regulator MFD component to load
> when the top-level MFD component loads?

the core driver adds sub devices, but in case of DT, the number of subdevices 
is zero AFAICS (tps6586x_parse_dt). However, these subdevs do not include the 
regulators.

Also, the regulator nodes don't have a compatibly property, so direct probing 
won't work.

I have no idea how the regulators are probed at all...