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

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Message-ID: <20220829082809.6xhd4zzs7ootax2z@houat>
Date:   Mon, 29 Aug 2022 10:28:09 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Noralf Trønnes <noralf@...nnes.org>
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>,
        Kevin Hilman <khilman@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Phil Elwell <phil@...pberrypi.com>,
        Mateusz Kwiatkowski <kfyatek+publicgit@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        linux-amlogic@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
        Dom Cobley <dom@...pberrypi.com>
Subject: Re: [PATCH v1 05/35] drm/connector: Add TV standard property

On Thu, Aug 25, 2022 at 05:13:29PM +0200, Noralf Trønnes wrote:
> 
> 
> Den 25.08.2022 15.44, skrev Maxime Ripard:
> > Hi,
> > 
> > On Sat, Aug 20, 2022 at 10:12:46PM +0200, Noralf Trønnes wrote:
> >>> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> >>> index 1e9996b33cc8..78275e68ff66 100644
> >>> --- a/include/drm/drm_connector.h
> >>> +++ b/include/drm/drm_connector.h
> >>> @@ -143,6 +143,32 @@ enum subpixel_order {
> >>>  
> >>>  };
> >>>  
> >>> +#define DRM_MODE_TV_NORM_NTSC_443	(1 << 0)
> >>> +#define DRM_MODE_TV_NORM_NTSC_J		(1 << 1)
> >>> +#define DRM_MODE_TV_NORM_NTSC_M		(1 << 2)
> >>> +#define DRM_MODE_TV_NORM_PAL_60		(1 << 3)
> >>> +#define DRM_MODE_TV_NORM_PAL_B		(1 << 4)
> >>> +#define DRM_MODE_TV_NORM_PAL_D		(1 << 5)
> >>> +#define DRM_MODE_TV_NORM_PAL_G		(1 << 6)
> >>> +#define DRM_MODE_TV_NORM_PAL_H		(1 << 7)
> >>> +#define DRM_MODE_TV_NORM_PAL_I		(1 << 8)
> >>> +#define DRM_MODE_TV_NORM_PAL_M		(1 << 9)
> >>> +#define DRM_MODE_TV_NORM_PAL_N		(1 << 10)
> >>> +#define DRM_MODE_TV_NORM_PAL_NC		(1 << 11)
> >>> +#define DRM_MODE_TV_NORM_SECAM_60	(1 << 12)
> >>> +#define DRM_MODE_TV_NORM_SECAM_B	(1 << 13)
> >>> +#define DRM_MODE_TV_NORM_SECAM_D	(1 << 14)
> >>> +#define DRM_MODE_TV_NORM_SECAM_G	(1 << 15)
> >>> +#define DRM_MODE_TV_NORM_SECAM_K	(1 << 16)
> >>> +#define DRM_MODE_TV_NORM_SECAM_K1	(1 << 17)
> >>> +#define DRM_MODE_TV_NORM_SECAM_L	(1 << 18)
> >>> +#define DRM_MODE_TV_NORM_HD480I		(1 << 19)
> >>> +#define DRM_MODE_TV_NORM_HD480P		(1 << 20)
> >>> +#define DRM_MODE_TV_NORM_HD576I		(1 << 21)
> >>> +#define DRM_MODE_TV_NORM_HD576P		(1 << 22)
> >>> +#define DRM_MODE_TV_NORM_HD720P		(1 << 23)
> >>> +#define DRM_MODE_TV_NORM_HD1080I	(1 << 24)
> >>> +
> >>
> >> This is an area where DRM overlaps with v4l2, see:
> >> - include/dt-bindings/display/sdtv-standards.h
> >> - v4l2_norm_to_name()
> >>
> >> Maybe we should follow suit, but if we do our own thing please mention
> >> why in the commit message.
> > 
> > Are you suggesting that we'd share that definition with v4l2?
> > 
> 
> If possible, yes.
> 
> > I've tried to share some code in the past between v4l2 and DRM, and it
> > got completely shut down so it's not something I'd like to try again, if
> > possible.
> > 
> 
> But that is a good enough reason not to do so. I just got the impression
> from some of Laurent's emails a while back that there was some
> cooperativ atmosphere, but I might be mistaken in my reading/understanding.

Here's the original thread:
https://lore.kernel.org/lkml/cover.8ec406bf8f4f097e9dc909d5aac466556822f592.1555487650.git-series.maxime.ripard@bootlin.com/

It ended up stalling completely, without any will from either DRM or
v4l2 to get this through. So I will not work on anything like that until
both maintainership teams have expressed that it's something they
actually want.

> It is ofc possible to just copy the values from sdtv-standards.h, but I
> see that hd* is missing from that list, so not sure if there's much
> point if it has to be extended without changing the source.

HD formats were dropped, so it's not a big deal. However, we are missing
a few formats, but that were never used by either nouveau, i915 or any
other driver. I'm not sure it's worth adding at that point, and we can
always extend it later.

Maxime

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