linux-kernel - Re: [PATCH v4 03/10] drm: Add enum conversion from/to HDMI_COLORSPACE to DRM_COLOR

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Message-ID: <3356228.ElGaqSPkdT@workhorse>
Date: Wed, 19 Nov 2025 13:48:13 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Harry Wentland <harry.wentland@....com>, Leo Li <sunpeng.li@....com>,
 Rodrigo Siqueira <siqueira@...lia.com>,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Sandy Huang <hjc@...k-chips.com>,
 Heiko Stübner <heiko@...ech.de>,
 Andy Yan <andy.yan@...k-chips.com>,
 Jani Nikula <jani.nikula@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Tvrtko Ursulin <tursulin@...ulin.net>, kernel@...labora.com,
 amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, Marius Vlad <marius.vlad@...labora.com>
Subject:
 Re: [PATCH v4 03/10] drm: Add enum conversion from/to HDMI_COLORSPACE to
 DRM_COLOR_FORMAT

On Wednesday, 19 November 2025 05:16:48 Central European Standard Time Laurent Pinchart wrote:
> On Mon, Nov 17, 2025 at 08:11:47PM +0100, Nicolas Frattaroli wrote:
> > From: Marius Vlad <marius.vlad@...labora.com>
> > 
> > This would please the compiler to have a enum transformation from one to
> > another even though the values are the same. It should also make things
> 
> The hdmi_colorspace enumerators are defined as (with comments added to
> make the values explicit)
> 
> enum hdmi_colorspace {
> 	HDMI_COLORSPACE_RGB,			/* 0 */
> 	HDMI_COLORSPACE_YUV422,			/* 1 */
> 	HDMI_COLORSPACE_YUV444,			/* 2 */
> 	HDMI_COLORSPACE_YUV420,			/* 3 */
> 	HDMI_COLORSPACE_RESERVED4,		/* 4 */
> 	HDMI_COLORSPACE_RESERVED5,		/* 5 */
> 	HDMI_COLORSPACE_RESERVED6,		/* 6 */
> 	HDMI_COLORSPACE_IDO_DEFINED,		/* 7 */
> };
> 
> and the DRM color formats as (after patch 02/10)
> 
> enum drm_color_format {
> 	DRM_COLOR_FORMAT_NONE			= 0,		/* 0 */
> 	DRM_COLOR_FORMAT_RGB444			= (1 << 0),	/* 1 */
> 	DRM_COLOR_FORMAT_YCBCR422		= (1 << 1),	/* 2 */
> 	DRM_COLOR_FORMAT_YCBCR444		= (1 << 2),	/* 4 */
> 	DRM_COLOR_FORMAT_YCBCR420		= (1 << 3),	/* 8 */
> 	/* auto case, driver will set the color_format */
> 	DRM_COLOR_FORMAT_AUTO			= (1 << 4),	/* 16 */
> };
> 
> Contrary to what is stated in the commit message, the values are not the
> same. Maybe you confused DRM_COLOR_FORMAT_* with DRM_MODE_COLOR_FORMAT_*
> ?

It's possible the equality got lost during my refactor, but I think
the needless enum conversions between like 4 different things should
be minimised anyway, so I'll look into getting rid of as much of this
as possible.

> 
> > obvious that we use different enums.
> > 
> > Signed-off-by: Marius Vlad <marius.vlad@...labora.com>
> > ---
> >  drivers/gpu/drm/drm_connector.c | 18 ++++++++++++++++++
> >  include/drm/drm_connector.h     |  3 +++
> >  2 files changed, 21 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > index 0ad7be0a2d09..61c077b67ac3 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -1384,6 +1384,24 @@ drm_color_format_enum_to_color_format(enum drm_color_format_enum fmt_enum)
> >  	}
> >  }
> >  
> > +enum hdmi_colorspace
> > +color_format_to_hdmi_colorspace(enum drm_color_format fmt)
> > +{
> > +	switch (fmt) {
> > +	default:
> > +	case DRM_COLOR_FORMAT_AUTO:
> > +	case DRM_COLOR_FORMAT_RGB444:
> > +		return HDMI_COLORSPACE_RGB;
> > +	case DRM_COLOR_FORMAT_YCBCR444:
> > +		return HDMI_COLORSPACE_YUV444;
> > +	case DRM_COLOR_FORMAT_YCBCR422:
> > +		return HDMI_COLORSPACE_YUV422;
> > +	case DRM_COLOR_FORMAT_YCBCR420:
> > +		return HDMI_COLORSPACE_YUV420;
> > +	}
> > +}
> > +EXPORT_SYMBOL(color_format_to_hdmi_colorspace);
> > +
> >  /**
> >   * drm_get_color_format_name - return a string for color format
> >   * @colorspace: color format to compute name of
> > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> > index a071079fd3ad..e044976c8d76 100644
> > --- a/include/drm/drm_connector.h
> > +++ b/include/drm/drm_connector.h
> > @@ -2586,6 +2586,9 @@ drm_color_format_to_color_format_enum(enum drm_color_format fmt);
> >  u32
> >  drm_color_format_enum_to_color_format(enum drm_color_format_enum fmt_enum);
> >  
> > +enum hdmi_colorspace
> > +color_format_to_hdmi_colorspace(enum drm_color_format fmt);
> > +
> >  /**
> >   * drm_for_each_connector_iter - connector_list iterator macro
> >   * @connector: &struct drm_connector pointer used as cursor
> 
>