Date:   Tue, 16 Aug 2022 11:49:22 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Noralf Trønnes <noralf@...nnes.org>
Cc:     Jernej Skrabec <jernej.skrabec@...il.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Jerome Brunet <jbrunet@...libre.com>,
        Samuel Holland <samuel@...lland.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel@...ll.ch>, Emma Anholt <emma@...olt.net>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Kevin Hilman <khilman@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Phil Elwell <phil@...pberrypi.com>,
        Mateusz Kwiatkowski <kfyatek+publicgit@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        linux-amlogic@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
        Dom Cobley <dom@...pberrypi.com>
Subject: Re: [PATCH v1 05/35] drm/connector: Add TV standard property

On Tue, Aug 16, 2022 at 11:42:20AM +0200, Noralf Trønnes wrote:
> 
> 
> Den 16.08.2022 10.26, skrev Maxime Ripard:
> > Hi,
> > 
> > On Mon, Aug 08, 2022 at 02:44:56PM +0200, Noralf Trønnes wrote:
> >> Den 29.07.2022 18.34, 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 bitmask 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.
> >>>
> >>> We'll then be able to phase out the older tv mode property.
> >>>
> >>> Signed-off-by: Maxime Ripard <maxime@...no.tech>
> >>>
> >>
> >> Please also update Documentation/gpu/kms-properties.csv
> >>
> >> Requirements for adding a new property is found in
> >> Documentation/gpu/drm-kms.rst
> > 
> > I knew this was going to be raised at some point, so I'm glad it's that
> > early :)
> > 
> > I really don't know what to do there. If we stick by our usual rules,
> > then we can't have any of that work merged.
> > 
> > However, I think the status quo is not really satisfactory either.
> > Indeed, we have a property, that doesn't follow those requirements
> > either, with a driver-specific content, and that stands in the way of
> > fixes and further improvements at both the core framework and driver
> > levels.
> > 
> > So having that new property still seems like a net improvement at the
> > driver, framework and uAPI levels, even if it's not entirely following
> > the requirements we have in place.
> > 
> > Even more so since, realistically, those kind of interfaces will never
> > get any new development on the user-space side of things, it's
> > considered by everyone as legacy.
> > 
> > This also is something we need to support at some point if we want to
> > completely deprecate the fbdev drivers and provide decent alternatives
> > in KMS.
> > 
> > So yeah, strictly speaking, we would not qualify for our requirements
> > there. I still think we have a strong case for an exception though.
>
> Which requirements would that be? The only one I can see is the
> documentation and maybe an IGT test.

This is the one I had in mind
https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements

I overlooked yours obviously, so I'll update my patches to fix it.

Maxime

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