linux-kernel - Re: [PATCH v5 13/22] drm/modes: Introduce the tv

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Date:   Mon, 17 Oct 2022 12:21:14 +0200
From:   Noralf Trønnes <noralf@...nnes.org>
To:     kfyatek+publicgit@...il.com, Maxime Ripard <maxime@...no.tech>,
        Karol Herbst <kherbst@...hat.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Lyude Paul <lyude@...hat.com>,
        Maxime Ripard <mripard@...nel.org>,
        Emma Anholt <emma@...olt.net>, Chen-Yu Tsai <wens@...e.org>,
        Samuel Holland <samuel@...lland.org>,
        Ben Skeggs <bskeggs@...hat.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>
Cc:     Dom Cobley <dom@...pberrypi.com>, linux-sunxi@...ts.linux.dev,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        nouveau@...ts.freedesktop.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-arm-kernel@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org,
        Hans de Goede <hdegoede@...hat.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Noralf Trønnes <noralf@...nnes.org>
Subject: Re: [PATCH v5 13/22] drm/modes: Introduce the tv_mode property as a
 command-line option



Den 16.10.2022 19.51, skrev Mateusz Kwiatkowski:
> Hi Maxime, Noralf & everyone,
> 
> I'd like to address Noralf here in particular, and refer to these discussions
> from the past:
> 
> - https://lore.kernel.org/linux-arm-kernel/2f607c7d-6da1-c8df-1c02-8dd344a92343@gmail.com/
> - https://lore.kernel.org/linux-arm-kernel/9e76a508-f469-a54d-ecd7-b5868ca99af4@tronnes.org/
> 
>> @@ -2230,20 +2256,22 @@ struct drm_named_mode {
>>  	unsigned int xres;
>>  	unsigned int yres;
>>  	unsigned int flags;
>> +	unsigned int tv_mode;
>>  };
> 
> I saw that you (Noralf) opposed my suggestion about the DRM_MODE_TV_MODE_NONE
> enum value in enum drm drm_connector_tv_mode. I get your argumentation, and I'm
> not gonna argue, but I still don't like the fact that struct drm_named_mode now
> includes a field that is only relevant for analog TV modes, has no "none" value,
> and yet the type is supposed to be generic enough to be usable for other types
> of outputs as well.
> 
> It's true that it can just be ignored (as Maxime mentioned in his response to
> my e-mail linked above), and now the value of 0 corresponds to
> DRM_MODE_TV_MODE_NTSC, which is a rather sane default, but it still feels messy
> to me.
> 
> I'm not gonna force my opinion here, but I wanted to bring your attention to
> this issue, maybe you have some other solution in mind for this problem. Or if
> you don't see that as a problem at all, that's fine, too.
> 

I hadn't looked at this patch in detail before, but you're right this,
together with drm_atomic_helper_connector_tv_reset(), will overwrite
tv.mode unconditionally regardless of tv_mode being present in video= or
not. We need a tv_mode_specified flag like we have for bpp and refresh.

Noralf.