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Date:   Tue, 18 Oct 2022 11:33:53 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Noralf =?utf-8?Q?Tr=C3=B8nnes?= <noralf@tronnes.org>
Cc:     Karol Herbst <kherbst@redhat.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
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Subject: Re: [PATCH v5 12/22] drm/connector: Add a function to lookup a TV
 mode by its name
Message-ID: <20221018093353.pt4vset6o2ldxrbs@houat>
References: <20220728-rpi-analog-tv-properties-v5-0-d841cc64fe4b@cerno.tech>
 <20220728-rpi-analog-tv-properties-v5-12-d841cc64fe4b@cerno.tech>
 <7dcf479c-8ac7-ed47-8587-30268684373c@tronnes.org>
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On Mon, Oct 17, 2022 at 12:44:45PM +0200, Noralf Tr=F8nnes wrote:
> Den 13.10.2022 15.18, skrev Maxime Ripard:
> > As part of the command line parsing rework coming in the next patches,
> > we'll need to lookup drm_connector_tv_mode values by their name, already
> > defined in drm_tv_mode_enum_list.
> >=20
> > In order to avoid any code duplication, let's do a function that will
> > perform a lookup of a TV mode name and return its value.
> >=20
> > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > ---
> >  drivers/gpu/drm/drm_connector.c | 24 ++++++++++++++++++++++++
> >  include/drm/drm_connector.h     |  2 ++
> >  2 files changed, 26 insertions(+)
> >=20
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_conn=
ector.c
> > index 820f4c730b38..30611c616435 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -991,6 +991,30 @@ static const struct drm_prop_enum_list drm_tv_mode=
_enum_list[] =3D {
> >  };
> >  DRM_ENUM_NAME_FN(drm_get_tv_mode_name, drm_tv_mode_enum_list)
> > =20
> > +/**
> > + * drm_get_tv_mode_from_name - Translates a TV mode name into its enum=
 value
> > + * @name: TV Mode name we want to convert
> > + * @len: Length of @name
> > + *
> > + * Translates @name into an enum drm_connector_tv_mode.
> > + *
> > + * Returns: the enum value on success, a negative errno otherwise.
> > + */
> > +int drm_get_tv_mode_from_name(const char *name, size_t len)
>=20
> Do we really need to pass in length here? item->name has to always be
> NUL terminated otherwise things would break elsewhere, so it shouldn't
> be necessary AFAICS.

The only user so far is the command-line parsing code, and we might very
well have an option after the tv_mode, something like
720x480i,tv_mode=3DNTSC,rotate=3D180

In this case, we won't get a NULL-terminated name.

Maxime