Re: [PATCH v2 09/33] drm/connector: Add TV standard property

From: Maxime Ripard <maxime@cerno.tech>
To: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Ben Skeggs <bskeggs@redhat.com>, David Airlie <airlied@linux.ie>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Emma Anholt <emma@anholt.net>, Karol Herbst <kherbst@redhat.com>,
	Samuel Holland <samuel@sholland.org>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel@ffwll.ch>, Lyude Paul <lyude@redhat.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	Chen-Yu Tsai <wens@csie.org>, Hans de Goede <hdegoede@redhat.com>,
	nouveau@lists.freedesktop.org,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Dave Stevenson <dave.stevenson@raspberrypi.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Phil Elwell <phil@raspberrypi.com>,
	intel-gfx@lists.freedesktop.org, Dom Cobley <dom@raspberrypi.com>,
	linux-sunxi@lists.linux.dev,
	Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 09/33] drm/connector: Add TV standard property
Date: Mon, 26 Sep 2022 12:01:31 +0200	[thread overview]
Message-ID: <20220926100131.o5xtslzcmez5z2r3@houat> (raw)
In-Reply-To: <80138f62-faec-5f7e-a8bd-235318a4e4c2@tronnes.org>

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On Sat, Sep 24, 2022 at 05:52:29PM +0200, Noralf Trønnes wrote:
> Den 22.09.2022 16.25, skrev Maxime Ripard:
> > The TV mode property has been around for a while now to select and get the
> > current TV mode output on an analog TV connector.
> > 
> > Despite that property name being generic, its content isn't and has been
> > driver-specific which makes it hard to build any generic behaviour on top
> > of it, both in kernel and user-space.
> > 
> > Let's create a new enum tv norm property, that can contain any of the
> > analog TV standards currently supported by kernel drivers. Each driver can
> > then pass in a bitmask of the modes it supports, and the property
> > creation function will filter out the modes not supported.
> > 
> > We'll then be able to phase out the older tv mode property.
> > 
> > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
>
> Please can you add per patch changelogs, it's hard to review when I have
> to recall what might have happened with each patch. If you do it drm
> style and put in the commit message it should be easy enough to do.

I certainly don't want to start that discussion, but I'm really not a
fan of that format either. I'll do it for that series if you prefer.

> > +/**
> > + * enum drm_connector_tv_mode - Analog TV output mode
> > + *
> > + * This enum is used to indicate the TV output mode used on an analog TV
> > + * connector.
> > + *
> > + * WARNING: The values of this enum is uABI since they're exposed in the
> > + * "TV mode" connector property.
> > + */
> > +enum drm_connector_tv_mode {
> > +	/**
> > +	 * @DRM_MODE_TV_MODE_NONE: Placeholder to not default on one
> > +	 * variant or the other when nothing is set.
> > +	 */
> > +	DRM_MODE_TV_MODE_NONE = 0,
> 
> How is this supposed to be used?

It's not supposed to be used. It was a suggestion from Mateusz to avoid
to default to any standard when we don't initialize something. I don't
have any strong feeling about it, so I can drop it if you prefer.

Maxime

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