linux-kernel - Re: [PATCH v1 07/35] drm/modes: Only consider bpp and refresh before options

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Message-ID: <CAMuHMdWa9soLHSvmxWqjKAO93WhViww6GZiC9qh0RccVENPRYw@mail.gmail.com>
Date:   Fri, 12 Aug 2022 15:25:39 +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 07/35] drm/modes: Only consider bpp and refresh before options

Hi Maxime,

On Fri, Jul 29, 2022 at 6:35 PM Maxime Ripard <maxime@...no.tech> wrote:
> Some video= options might have a value that contains a dash. However, the
> command line parsing mode considers all dashes as the separator between the
> mode and the bpp count.
>
> Let's rework the parsing code a bit to only consider a dash as the bpp
> separator if it before a comma, the options separator.
>
> A follow-up patch will add a unit-test for this once such an option is
> introduced.
>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>

Thanks for your patch!

Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>

> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -1819,20 +1819,22 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
>
>         name = mode_option;
>
> +       /* Locate the start of named options */
> +       options_ptr = strchr(name, ',');
> +       if (options_ptr)
> +               options_off = options_ptr - name;
> +       else
> +               options_off = strlen(name);
> +
>         /* Try to locate the bpp and refresh specifiers, if any */
> -       bpp_ptr = strchr(name, '-');
> +       bpp_ptr = strnchr(name, options_off, '-');

Probably you still want to add a check that the next character
is actually a digit, cfr. my "[PATCH v2 5/5] drm/modes:
parse_cmdline: Add support for named modes containing dashes"
(https://lore.kernel.org/dri-devel/2eb205da88c3cb19ddf04d167ece4e16a330948b.1657788997.git.geert@linux-m68k.org)?

>         if (bpp_ptr)
>                 bpp_off = bpp_ptr - name;
>
> -       refresh_ptr = strchr(name, '@');
> +       refresh_ptr = strnchr(name, options_off, '@');
>         if (refresh_ptr)
>                 refresh_off = refresh_ptr - name;
>
> -       /* Locate the start of named options */
> -       options_ptr = strchr(name, ',');
> -       if (options_ptr)
> -               options_off = options_ptr - name;
> -
>         /* Locate the end of the name / resolution, and parse it */
>         if (bpp_ptr) {
>                 mode_end = bpp_off;

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