Re: [PATCH v5 12/22] drm/connector: Add a function to lookup a TV mode by its name

[Maxime Ripard]

On Mon, Oct 17, 2022 at 12:44:45PM +0200, Noralf Trønnes 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.
> > 
> > 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.
> > 
> > Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/drm_connector.c | 24 ++++++++++++++++++++++++
> >  include/drm/drm_connector.h     |  2 ++
> >  2 files changed, 26 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.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[] = {
> >  };
> >  DRM_ENUM_NAME_FN(drm_get_tv_mode_name, drm_tv_mode_enum_list)
> >  
> > +/**
> > + * 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)
> 
> 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=NTSC,rotate=180

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

Maxime