linux-kernel - Re: [PATCH v1 34/35] drm/modes: Introduce the tv

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Date:   Fri, 12 Aug 2022 15:31:19 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Maxime Ripard <maxime@...no.tech>
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>,
        Noralf Trønnes <noralf@...nnes.org>,
        Kevin Hilman <khilman@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Maxime Ripard <mripard@...nel.org>,
        linux-sunxi@...ts.linux.dev,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Phil Elwell <phil@...pberrypi.com>,
        Mateusz Kwiatkowski <kfyatek+publicgit@...il.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Dom Cobley <dom@...pberrypi.com>
Subject: Re: [PATCH v1 34/35] drm/modes: Introduce the tv_mode property as a
 command-line option

Hi Maxime,

On Fri, Jul 29, 2022 at 6:37 PM Maxime Ripard <maxime@...no.tech> wrote:
> Our new tv mode option allows to specify the TV mode from a property.
> However, it can still be useful, for example to avoid any boot time
> artifact, to set that property directly from the kernel command line.
>
> Let's add some code to allow it, and some unit tests to exercise that code.
>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>

Thanks for your patch!

> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -1677,6 +1677,80 @@ static int drm_mode_parse_panel_orientation(const char *delim,
>         return 0;
>  }
>
> +#define TV_OPTION_EQUAL(value, len, option) \
> +       ((strlen(option) == len) && !strncmp(value, option, len))
> +
> +static int drm_mode_parse_tv_mode(const char *delim,
> +                                 struct drm_cmdline_mode *mode)
> +{
> +       const char *value;
> +       unsigned int len;
> +
> +       if (*delim != '=')
> +               return -EINVAL;
> +
> +       value = delim + 1;
> +       delim = strchr(value, ',');
> +       if (!delim)
> +               delim = value + strlen(value);
> +
> +       len = delim - value;
> +       if (TV_OPTION_EQUAL(value, len, "NTSC-443"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_NTSC_443;
> +       else if (TV_OPTION_EQUAL(value, len, "NTSC-J"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_NTSC_J;
> +       else if (TV_OPTION_EQUAL(value, len, "NTSC-M"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_NTSC_M;

[...]

You already have the array tv_norm_values[] from "[PATCH v1 05/35]
drm/connector: Add TV standard property". Can't you export that, and
loop over that array instead?

> +       else if (TV_OPTION_EQUAL(value, len, "HD480I"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_HD480I;
> +       else if (TV_OPTION_EQUAL(value, len, "HD480P"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_HD480P;
> +       else if (TV_OPTION_EQUAL(value, len, "HD576I"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_HD576I;
> +       else if (TV_OPTION_EQUAL(value, len, "HD576P"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_HD576P;
> +       else if (TV_OPTION_EQUAL(value, len, "HD720P"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_HD720P;
> +       else if (TV_OPTION_EQUAL(value, len, "HD1080I"))
> +               mode->tv_mode = DRM_MODE_TV_NORM_HD1080I;

The names in tv_norm_values[] use lower-case, while you use upper-case
here.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds