Re: [PATCH v1 05/35] drm/connector: Add TV standard property

From: Maxime Ripard <maxime@cerno.tech>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Emma Anholt" <emma@anholt.net>,
	"Neil Armstrong" <narmstrong@baylibre.com>,
	"David Airlie" <airlied@linux.ie>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Phil Elwell" <phil@raspberrypi.com>,
	"Jerome Brunet" <jbrunet@baylibre.com>,
	"Samuel Holland" <samuel@sholland.org>,
	"Kevin Hilman" <khilman@baylibre.com>,
	"Jernej Skrabec" <jernej.skrabec@gmail.com>,
	"Chen-Yu Tsai" <wens@csie.org>,
	linux-sunxi@lists.linux.dev,
	"Martin Blumenstingl" <martin.blumenstingl@googlemail.com>,
	"open list:ARM/Amlogic Meson..."
	<linux-amlogic@lists.infradead.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	"Dom Cobley" <dom@raspberrypi.com>,
	"Dave Stevenson" <dave.stevenson@raspberrypi.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Mateusz Kwiatkowski" <kfyatek+publicgit@gmail.com>,
	"Noralf Trønnes" <noralf@tronnes.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>
Subject: Re: [PATCH v1 05/35] drm/connector: Add TV standard property
Date: Wed, 17 Aug 2022 15:18:54 +0200	[thread overview]
Message-ID: <20220817131854.jwmhqvhfhp77bbr3@houat> (raw)
In-Reply-To: <CAMuHMdU57g1rNoLo65jhLK8mk4YkNEbMz1E7XKWk2dnCxTr=gg@mail.gmail.com>

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On Wed, Aug 17, 2022 at 03:05:52PM +0200, Geert Uytterhoeven wrote:
> Hi Maxime,
> 
> On Wed, Aug 17, 2022 at 1:15 PM Maxime Ripard <maxime@cerno.tech> wrote:
> > On Wed, Aug 17, 2022 at 10:35:07AM +0200, Geert Uytterhoeven wrote:
> > > On Wed, Aug 17, 2022 at 9:47 AM Maxime Ripard <maxime@cerno.tech> wrote:
> > > > On Wed, Aug 17, 2022 at 09:31:18AM +0200, Geert Uytterhoeven wrote:
> > > > > On Tue, Aug 16, 2022 at 5:50 PM Maxime Ripard <maxime@cerno.tech> wrote:
> > > > > > On Tue, Aug 16, 2022 at 04:43:44PM +0200, Geert Uytterhoeven wrote:
> > > > > > > > > > > Either you have to add them here (e.g. "hd720p50" and "hd720p60"), or
> > > > > > > > > > > handle them through "@<refresh>".  The latter would impact "[PATCH v1
> > > > > > > > > > > 09/35] drm/modes: Move named modes parsing to a separate function", as
> > > > > > > > > > > currently a named mode and a refresh rate can't be specified both.
> > > > > > > > > >
> > > > > > > > > > I think the former would make more sense. It simplifies a bit the
> > > > > > > > > > parser, and we're going to use a named mode anyway.
> > > > > > > > > >
> > > > > > > > > > > As "[PATCH v1 34/35] drm/modes: Introduce the tv_mode property as a
> > > > > > > > > > > command-line option" uses a separate "tv_mode" option, and not the main
> > > > > > > > > > > mode name, I think you want to add them here.
> > > > > > > > > >
> > > > > > > > > > It's a separate story I think, we could have a named mode hd720p50,
> > > > > > > > > > which would be equivalent to 1280x720,tv_mode=hd720p
> > > > > > > > >
> > > > > > > > > So where's the field rate in "1280x720,tv_mode=hd720p"?
> > > > > > > >
> > > > > > > > Yeah, sorry I meant 1280x720@50,tv_mode=hd720p
> > > > > > >
> > > > > > > Above you said "I think the former would make more sense", so that
> > > > > > > should be "1280x720,tv_mode=hd720p50"?
> > > > > >
> > > > > > No, 720p at 50Hz would be either hd720p50 or 1280x720@50,tv_mode=hd720p
> > > > > > and 60Hz would be hd720p60 or 1280x720@60,tv_mode=hd720p
> > > > >
> > > > > I disagree: hd720p50 and hd720p60 are different TV modes.
> > > >
> > > > I agree, and I don't see how that command-line doesn't express that?
> > >
> > > Oh, I see what you mean: yes, it expresses that.
> > > But it is inconsistent with the NTSC/PAL/SECAM/hd{480,576}[ip] modes,
> > > where the TV mode specifies both number of lines and frame rate.
> >
> > Only if we're using a named mode, and naming is hard :)
> 
> That's not true: "640x480,tv_mode=PAL-N" would give me a mode with
> 625 lines and 25 frames/s, "640x480,tv_mode=PAL-M" would give me a
> mode with 525 lines and 30 frames/s.

In that series, "640x480,tv_mode=PAL-N" would be rejected as invalid:

https://lore.kernel.org/dri-devel/20220728-rpi-analog-tv-properties-v1-14-3d53ae722097@cerno.tech/

Maxime

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