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Date:   Wed, 7 Sep 2022 14:10:09 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Mateusz Kwiatkowski <kfyatek@gmail.com>
Cc:     Ben Skeggs <bskeggs@redhat.com>, David Airlie <airlied@linux.ie>,
        Chen-Yu Tsai <wens@csie.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Lyude Paul <lyude@redhat.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Samuel Holland <samuel@sholland.org>,
        Karol Herbst <kherbst@redhat.com>,
        Noralf =?utf-8?Q?Tr=C3=B8nnes?= <noralf@tronnes.org>,
        Emma Anholt <emma@anholt.net>, Daniel Vetter <daniel@ffwll.ch>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        linux-arm-kernel@lists.infradead.org,
        Phil Elwell <phil@raspberrypi.com>,
        intel-gfx@lists.freedesktop.org,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        dri-devel@lists.freedesktop.org, Dom Cobley <dom@raspberrypi.com>,
        linux-kernel@vger.kernel.org, nouveau@lists.freedesktop.org,
        linux-sunxi@lists.linux.dev,
        Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH v2 09/41] drm/connector: Add TV standard property
Message-ID: <20220907121009.toizfolruuazcrns@houat>
References: <20220728-rpi-analog-tv-properties-v2-0-459522d653a7@cerno.tech>
 <20220728-rpi-analog-tv-properties-v2-9-459522d653a7@cerno.tech>
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Hi,

On Fri, Sep 02, 2022 at 12:00:33AM +0200, Mateusz Kwiatkowski wrote:
> W dniu 29.08.2022 o 15:11, Maxime Ripard pisze:
> > 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 t=
op
> > 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.
>=20
> This is not a bitmask property anymore, you've just changed it to an enum.
> The commit message is now misleading.
>=20
> > +static const struct drm_prop_enum_list drm_tv_mode_enum_list[] =3D {
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_NTSC_443, "NTSC-443" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_NTSC_J, "NTSC-J" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_NTSC_M, "NTSC-M" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_60, "PAL-60" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_B, "PAL-B" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_D, "PAL-D" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_G, "PAL-G" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_H, "PAL-H" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_I, "PAL-I" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_M, "PAL-M" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_N, "PAL-N" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_PAL_NC, "PAL-Nc" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_60, "SECAM-60" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_B, "SECAM-B" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_D, "SECAM-D" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_G, "SECAM-G" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_K, "SECAM-K" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_K1, "SECAM-K1" },
> > +=A0=A0 =A0{ DRM_MODE_TV_MODE_SECAM_L, "SECAM-L" },
> > +};
>=20
> I did not comment on it the last time, but this list looks a little bit r=
andom.
>=20
> Compared to the standards defined by V4L2, you also define SECAM-60 (a go=
od
> thing to define, because why not), but don't define PAL-B1, PAL-D1, PAL-K,
> SECAM-H, SECAM-LC (whatever that is - probably just another name for SECA=
M-L,
> see my comment about PAL-Nc below), or NTSC-M-KR (a Korean variant of NTS=
C).
>=20
> Like I mentioned previously, I'm personally not a fan of including all th=
ose
> CCIR/ITU system variants, as they don't mean any difference to the output=
 unless
> there is an RF modulator involved. But I get it that they have already be=
en used
> and regressing probably wouldn't be a very good idea. But in that case ke=
eping
> it consistent with the set of values used by V4L2 would be wise, I think.

Ack. What would be the list of standards we'd absolutely need? NSTC-M,
NTSC-J, PAL-60, PAL-B, PAL-M, SECAM-60 and SECAM-B?

> > +/**
> > + * drm_mode_create_tv_properties - create TV specific connector proper=
ties
> > + * @dev: DRM device
> > + * @supported_tv_modes: Bitmask of TV modes supported (See DRM_MODE_TV=
_MODE_*)
> > +
> > + * Called by a driver's TV initialization routine, this function creat=
es
> > + * the TV specific connector properties for a given device.=A0 Caller =
is
> > + * responsible for allocating a list of format names and passing them =
to
> > + * this routine.
> > + *
> > + * Returns:
> > + * 0 on success or a negative error code on failure.
> > + */
> > +int drm_mode_create_tv_properties(struct drm_device *dev,
> > +=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0=A0 =A0=A0 unsigned int supported_tv_=
modes)
>=20
> supported_tv_modes is supposed to be a bitmask of BIT(DRM_MODE_TV_MODE_*)
> (or (1<<DRM_MODE_TV_MODE_*)) rather than DRM_MODE_TV_MODE_* directly, but=
 this
> is not said explicitly anywhere in this doc comment.

The argument doc mentions that it's a "Bitmask of TV modes supported
(See DRM_MODE_TV_MODE_*)", how would you improve it?

Thanks!
Maxime

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