linux-kernel - Re: [PATCH v4 00/30] drm: Analog TV Improvements

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Message-ID: <20221010121123.sn6rxj3iwubn5tkc@houat>
Date:   Mon, 10 Oct 2022 14:11:23 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Noralf Trønnes <noralf@...nnes.org>
Cc:     Jernej Skrabec <jernej.skrabec@...il.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Karol Herbst <kherbst@...hat.com>,
        Samuel Holland <samuel@...lland.org>,
        Lyude Paul <lyude@...hat.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Emma Anholt <emma@...olt.net>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        linux-arm-kernel@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        intel-gfx@...ts.freedesktop.org, linux-sunxi@...ts.linux.dev,
        Hans de Goede <hdegoede@...hat.com>,
        nouveau@...ts.freedesktop.org,
        Mateusz Kwiatkowski <kfyatek+publicgit@...il.com>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        linux-kernel@...r.kernel.org, Dom Cobley <dom@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>
Subject: Re: [PATCH v4 00/30] drm: Analog TV Improvements

On Sat, Oct 01, 2022 at 03:12:06PM +0200, Noralf Trønnes wrote:
> 
> 
> Den 29.09.2022 18.30, skrev Maxime Ripard:
> > Hi,
> > 
> > Here's a series aiming at improving the command line named modes support,
> > and more importantly how we deal with all the analog TV variants.
> > 
> > The named modes support were initially introduced to allow to specify the
> > analog TV mode to be used.
> > 
> > However, this was causing multiple issues:
> > 
> >   * The mode name parsed on the command line was passed directly to the
> >     driver, which had to figure out which mode it was suppose to match;
> > 
> >   * Figuring that out wasn't really easy, since the video= argument or what
> >     the userspace might not even have a name in the first place, but
> >     instead could have passed a mode with the same timings;
> > 
> >   * The fallback to matching on the timings was mostly working as long as
> >     we were supporting one 525 lines (most likely NSTC) and one 625 lines
> >     (PAL), but couldn't differentiate between two modes with the same
> >     timings (NTSC vs PAL-M vs NSTC-J for example);
> > 
> >   * There was also some overlap with the tv mode property registered by
> >     drm_mode_create_tv_properties(), but named modes weren't interacting
> >     with that property at all.
> > 
> >   * Even though that property was generic, its possible values were
> >     specific to each drivers, which made some generic support difficult.
> > 
> > Thus, I chose to tackle in multiple steps:
> > 
> >   * A new TV mode property was introduced, with generic values, each driver
> >     reporting through a bitmask what standard it supports to the userspace;
> > 
> >   * This option was added to the command line parsing code to be able to
> >     specify it on the kernel command line, and new atomic_check and reset
> >     helpers were created to integrate properly into atomic KMS;
> > 
> >   * The named mode parsing code is now creating a proper display mode for
> >     the given named mode, and the TV standard will thus be part of the
> >     connector state;
> > 
> >   * Two drivers were converted and tested for now (vc4 and sun4i), with
> >     some backward compatibility code to translate the old TV mode to the
> >     new TV mode;
> > 
> > Unit tests were created along the way.
> > 
> > One can switch from NTSC to PAL now using (on vc4)
> > 
> > modetest -M vc4  -s 53:720x480i -w 53:'TV mode':1 # NTSC
> > modetest -M vc4  -s 53:720x576i -w 53:'TV mode':4 # PAL
> > 
> > Let me know what you think,
> > Maxime
> > 
> 
> I suggest that you apply the patches that are reviewed, have merrit on
> their own and are not tied to the TV mode property.
> This will help in keeping this rather big patchset focused and ease the
> task for reviewers.
> 
> The following seems to be in that group:
> 
>   drm/tests: Order Kunit tests in Makefile
>   drm/atomic-helper: Rename drm_atomic_helper_connector_tv_reset to
> avoid ambiguity
>   drm/connector: Rename subconnector state variable
>   drm/atomic: Add TV subconnector property to get/set_property
>   drm/modes: Only consider bpp and refresh before options
>   drm/modes: parse_cmdline: Add support for named modes containing dashes
>   drm/vc4: vec: Fix definition of PAL-M mode

Yeah, that was my intention with this series, it's done now, thanks for the reminder :)

Maxime

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