[v5,05/12] drm/modes: Rewrite the command line parser

[Maxime Ripard]

Hi,

On Mon, Aug 19, 2019 at 09:20:00PM +0200, Thomas Graichen wrote:
> On Mon, Aug 19, 2019 at 8:54 PM Jernej Škrabec <jernej.skrabec at gmail.com> wrote:
> >
> > +CC: Thomas Graichen
> >
> > Dne ponedeljek, 17. junij 2019 ob 16:51:32 CEST je Maxime Ripard napisal(a):
> > > From: Maxime Ripard <maxime.ripard at free-electrons.com>
> > >
> > > Rewrite the command line parser in order to get away from the state machine
> > > parsing the video mode lines.
> > >
> > > Hopefully, this will allow to extend it more easily to support named modes
> > > and / or properties set directly on the command line.
> > >
> > > Reviewed-by: Noralf Trønnes <noralf at tronnes.org>
> > > Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
> >
> > Thomas reported to me that this patch breaks "video=CONNECTOR:e" kernel
> > parameter which he currently uses as a workaround for H6 HDMI monitor
> > detection issue on one STB.
> >
> > I suppose this is the same issue that Dmitry noticed.
> >
> > Thomas Graichen (in CC) can provide more information if needed.
>
> as jernej already mentioned i am currently having to use the kernel
> cmdline option video=HDMI-A-1:e to get a working hdmi output on an
> eachlink h6 mini tv box and was wondering that i did not get any hdmi
> output even with this option when switching from the
> https://github.com/megous/linux oprange-pi-5.2 to the orange-pi-5.3
> branch which seems to contain this patch.

Which kernel version is that based on?

> as i had no idea what might have caused the breakage of the hdmi
> output and did a full bisect of the kernel between those two
> versions, which ended reliably at exactly this patch - so i guess
> there is a regression at least with the video=CONNECTOR:e option
> (maybe others too?) with this patches code which makes it not
> working anymore.

I'm not sure I'll have the time to look into it this week (or the
next, unfortunately). However, the e parameter is supposed to be
parsed by drm_mode_parse_cmdline_extra, which in turn is supposed to
be called there:
https://elixir.bootlin.com/linux/v5.3-rc5/source/drivers/gpu/drm/drm_modes.c#L1810

If you can test that, having an idea of if that function is called,
which return code it returns, and if it isn't if why would be super
helpful.

Thanks!
Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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