Re: [PATCH v7 21/36] drm/connector: hdmi: Add Broadcast RGB property

Pekka Paalanen
2024-02-23T09:31:55Z

[-- Attachment #1.1: Type: text/plain, Size: 4534 bytes --]

On Thu, 22 Feb 2024 19:14:07 +0100
Maxime Ripard <mripard@kernel.org> wrote:

> The i915 driver has a property to force the RGB range of an HDMI output.
> The vc4 driver then implemented the same property with the same
> semantics. KWin has support for it, and a PR for mutter is also there to
> support it.
>
> Both drivers implementing the same property with the same semantics,
> plus the userspace having support for it, is proof enough that it's
> pretty much a de-facto standard now and we can provide helpers for it.
>
> Let's plumb it into the newly created HDMI connector.
>
> Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
> ---
> Documentation/gpu/kms-properties.csv | 1 -
> drivers/gpu/drm/drm_atomic.c | 2 +
> drivers/gpu/drm/drm_atomic_state_helper.c | 4 +-
> drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
> drivers/gpu/drm/drm_connector.c | 89 +++++++++++++++++++++++++++++++
> include/drm/drm_connector.h | 36 +++++++++++++
> 6 files changed, 134 insertions(+), 2 deletions(-)

...

> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 591d2d500f61..6ffe59d01698 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -1212,6 +1212,29 @@ static const u32 dp_colorspaces =
> BIT(DRM_MODE_COLORIMETRY_BT2020_CYCC) |
> BIT(DRM_MODE_COLORIMETRY_BT2020_YCC);
>
> +static const struct drm_prop_enum_list broadcast_rgb_names[] = {
> + { DRM_HDMI_BROADCAST_RGB_AUTO, "Automatic" },
> + { DRM_HDMI_BROADCAST_RGB_FULL, "Full" },
> + { DRM_HDMI_BROADCAST_RGB_LIMITED, "Limited 16:235" },
> +};
> +
> +/*
> + * drm_hdmi_connector_get_broadcast_rgb_name - Return a string for HDMI connector RGB broadcast selection
> + * @broadcast_rgb: Broadcast RGB selection to compute name of
> + *
> + * Returns: the name of the Broadcast RGB selection, or NULL if the type
> + * is not valid.
> + */
> +const char *
> +drm_hdmi_connector_get_broadcast_rgb_name(enum drm_hdmi_broadcast_rgb broadcast_rgb)
> +{
> + if (broadcast_rgb > DRM_HDMI_BROADCAST_RGB_LIMITED)
> + return NULL;
> +
> + return broadcast_rgb_names[broadcast_rgb].name;
> +}
> +EXPORT_SYMBOL(drm_hdmi_connector_get_broadcast_rgb_name);
> +
> static const char * const output_format_str[] = {
> [HDMI_COLORSPACE_RGB] = "RGB",
> [HDMI_COLORSPACE_YUV420] = "YUV 4:2:0",
> @@ -1708,6 +1731,39 @@ EXPORT_SYMBOL(drm_connector_attach_dp_subconnector_property);
> /**
> * DOC: HDMI connector properties
> *
> + * Broadcast RGB (HDMI specific)
> + * Indicates the Quantization Range (Full vs Limited) used. The color
> + * processing pipeline will be adjusted to match the value of the
> + * property, and the Infoframes will be generated and sent accordingly.
> + *
> + * This property is only relevant if the HDMI output format is RGB. If
> + * it's one of the YCbCr variant, it will be ignored and the output will
> + * use a limited quantization range.
> + *
> + * The CRTC attached to the connector must be configured by user-space to
> + * always produce full-range pixels.
> + *
> + * The value of this property can be one of the following:
> + *
> + * Automatic:
> + * The quantization range is selected automatically based on the
> + * mode according to the HDMI specifications (HDMI 1.4b - Section
> + * 6.6 - Video Quantization Ranges).
> + *
> + * Full:
> + * Full quantization range is forced.
> + *
> + * Limited 16:235:
> + * Limited quantization range is forced. Unlike the name suggests,
> + * this works for any number of bits-per-component.
> + *
> + * Property values other than Automatic can result in colors being off (if
> + * limited is selected but the display expects full), or a black screen
> + * (if full is selected but the display expects limited).
> + *
> + * Drivers can set up this property by calling
> + * drm_connector_attach_broadcast_rgb_property().
> + *
> * content type (HDMI specific):
> * Indicates content type setting to be used in HDMI infoframes to indicate
> * content type for the external device, so that it adjusts its display

This piece of doc looks good to me, so

Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>

Thanks,
pq

[-- Attachment #1.2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]