Message-ID: <5934b4b2-3a99-4b6b-b3e3-e57eb82b9b16@suse.de>
Date: Thu, 1 Aug 2024 11:08:31 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Maxime Ripard <mripard@...nel.org>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Jonathan Corbet <corbet@....net>, Sandy Huang <hjc@...k-chips.com>,
 Heiko Stübner <heiko@...ech.de>,
 Chen-Yu Tsai <wens@...e.org>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Samuel Holland <samuel@...lland.org>, Andy Yan <andy.yan@...k-chips.com>
Cc: Hans Verkuil <hverkuil@...all.nl>,
 Sebastian Wick <sebastian.wick@...hat.com>,
 Ville Syrjälä <ville.syrjala@...ux.intel.com>,
 dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
 linux-sunxi@...ts.linux.dev, Dave Stevenson
 <dave.stevenson@...pberrypi.com>, Sui Jingfeng <sui.jingfeng@...ux.dev>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH v15 01/29] drm/connector: Introduce an HDMI connector
 initialization function

Hi

Am 27.05.24 um 15:57 schrieb Maxime Ripard:
> A lot of the various HDMI drivers duplicate some logic that depends on
> the HDMI spec itself and not really a particular hardware
> implementation.
>
> Output BPC or format selection, infoframe generation are good examples
> of such areas.
>
> This creates a lot of boilerplate, with a lot of variations, which makes
> it hard for userspace to rely on, and makes it difficult to get it right
> for drivers.
>
> In the next patches, we'll add a lot of infrastructure around the
> drm_connector and drm_connector_state structures, which will allow to
> abstract away the duplicated logic. This infrastructure comes with a few
> requirements though, and thus we need a new initialization function.
>
> Hopefully, this will make drivers simpler to handle, and their behaviour
> more consistent.
>
> Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> Reviewed-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Signed-off-by: Maxime Ripard <mripard@...nel.org>
> ---
>   drivers/gpu/drm/drm_connector.c | 39 +++++++++++++++++++++++++++++++++++++++
>   include/drm/drm_connector.h     |  5 +++++
>   2 files changed, 44 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index b0516505f7ae..d9961cce8245 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -450,10 +450,49 @@ int drmm_connector_init(struct drm_device *dev,
>   
>   	return 0;
>   }
>   EXPORT_SYMBOL(drmm_connector_init);
>   
> +/**
> + * drmm_connector_hdmi_init - Init a preallocated HDMI connector
> + * @dev: DRM device
> + * @connector: A pointer to the HDMI connector to init
> + * @funcs: callbacks for this connector
> + * @connector_type: user visible type of the connector
> + * @ddc: optional pointer to the associated ddc adapter
> + *
> + * Initialises a preallocated HDMI connector. Connectors can be
> + * subclassed as part of driver connector objects.
> + *
> + * Cleanup is automatically handled with a call to
> + * drm_connector_cleanup() in a DRM-managed action.
> + *
> + * The connector structure should be allocated with drmm_kzalloc().
> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + */
> +int drmm_connector_hdmi_init(struct drm_device *dev,
> +			     struct drm_connector *connector,
> +			     const struct drm_connector_funcs *funcs,
> +			     int connector_type,
> +			     struct i2c_adapter *ddc)

I know I'm late to the review.

Wouldn't it be better to make a separate HDMI-setup helper instead of 
yet another init function? The type of init function to use is mostly 
about memory management within the driver, while the new HDMI state is 
about features.

Maybe rather add something like drm_connector_init_hdmi_state(), which 
takes an initialized connector and sets all the values coming the other 
patches. Drivers would not have to subscribe to a certain way of memory 
management. AFAICT this would also allow to protect the helper and the 
new drm_connector.hdmi field behind DRM_DISPLAY_HDMI_STATE_HELPER. Best 
regards Thomas
> +{
> +	int ret;
> +
> +	if (!(connector_type == DRM_MODE_CONNECTOR_HDMIA ||
> +	      connector_type == DRM_MODE_CONNECTOR_HDMIB))
> +		return -EINVAL;
> +
> +	ret = drmm_connector_init(dev, connector, funcs, connector_type, ddc);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drmm_connector_hdmi_init);
> +
>   /**
>    * drm_connector_attach_edid_property - attach edid property.
>    * @connector: the connector
>    *
>    * Some connector types like DRM_MODE_CONNECTOR_VIRTUAL do not get a
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index fe88d7fc6b8f..4491c4c2fb6e 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -1902,10 +1902,15 @@ int drm_connector_init_with_ddc(struct drm_device *dev,
>   int drmm_connector_init(struct drm_device *dev,
>   			struct drm_connector *connector,
>   			const struct drm_connector_funcs *funcs,
>   			int connector_type,
>   			struct i2c_adapter *ddc);
> +int drmm_connector_hdmi_init(struct drm_device *dev,
> +			     struct drm_connector *connector,
> +			     const struct drm_connector_funcs *funcs,
> +			     int connector_type,
> +			     struct i2c_adapter *ddc);
>   void drm_connector_attach_edid_property(struct drm_connector *connector);
>   int drm_connector_register(struct drm_connector *connector);
>   void drm_connector_unregister(struct drm_connector *connector);
>   int drm_connector_attach_encoder(struct drm_connector *connector,
>   				      struct drm_encoder *encoder);
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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