linux-kernel - Re: [PATCH RFC/RFT 1/9] drm/connector: add CEC-related fields

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Message-ID: <20250107-amiable-poetic-rook-17da6e@houat>
Date: Tue, 7 Jan 2025 15:27:13 +0100
From: Maxime Ripard <mripard@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Dave Stevenson <dave.stevenson@...pberrypi.com>, 
	Maíra Canal <mcanal@...lia.com>, Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC/RFT 1/9] drm/connector: add CEC-related fields

Hi,

Thanks a lot for working on this.

On Wed, Dec 25, 2024 at 01:10:09AM +0200, Dmitry Baryshkov wrote:
> As a preparation to adding HDMI CEC helper code, add CEC-related fields
> to the struct drm_connector. Include both cec_adapter and cec_notifier,
> allowing drivers to select which one to use. The unregister callback
> is provided to let drivers unregister CEC-related data in a generic way
> without polluting drm_connector.c with dependencies on the CEC
> functions.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>  drivers/gpu/drm/drm_connector.c | 23 ++++++++++++++++++++++
>  include/drm/drm_connector.h     | 43 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 66 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 1383fa9fff9bcf31488453e209a36c6fe97be2f1..ef299733041e2c64bebd73c3fe21d4492bc07d3a 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -279,6 +279,7 @@ static int drm_connector_init_only(struct drm_device *dev,
>  	INIT_LIST_HEAD(&connector->probed_modes);
>  	INIT_LIST_HEAD(&connector->modes);
>  	mutex_init(&connector->mutex);
> +	mutex_init(&connector->cec.mutex);
>  	mutex_init(&connector->eld_mutex);
>  	mutex_init(&connector->edid_override_mutex);
>  	mutex_init(&connector->hdmi.infoframes.lock);
> @@ -698,6 +699,26 @@ static void drm_mode_remove(struct drm_connector *connector,
>  	drm_mode_destroy(connector->dev, mode);
>  }
>  
> +/**
> + * drm_connector_cec_unregister - clean up CEC registration
> + * @connector: connector to cleanup
> + *
> + * Reverse corresponding CEC registration. This function is supposed to be
> + * called only by bridge drivers which need to handle CEC manually. Normally
> + * CEC adapter or notifier are automatically unregistered during drm_connector
> + * teardown.
> + */
> +void drm_connector_cec_unregister(struct drm_connector *connector)
> +{
> +	mutex_lock(&connector->cec.mutex);
> +
> +	if (connector->cec.unregister)
> +		connector->cec.unregister(connector);
> +
> +	mutex_unlock(&connector->cec.mutex);
> +}
> +EXPORT_SYMBOL(drm_connector_cec_unregister);

Why do we need to have that function public?

>  /**
>   * drm_connector_cleanup - cleans up an initialised connector
>   * @connector: connector to cleanup
> @@ -718,6 +739,8 @@ void drm_connector_cleanup(struct drm_connector *connector)
>  
>  	platform_device_unregister(connector->hdmi_audio.codec_pdev);
>  
> +	drm_connector_cec_unregister(connector);
> +
>  	if (connector->privacy_screen) {
>  		drm_privacy_screen_put(connector->privacy_screen);
>  		connector->privacy_screen = NULL;
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index f13d597370a30dc1b14c630ee00145256052ba56..feecd02e7c698cc0c553b79048c9130f69121012 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -46,6 +46,7 @@ struct drm_property_blob;
>  struct drm_printer;
>  struct drm_privacy_screen;
>  struct drm_edid;
> +struct cec_adapter;
>  struct edid;
>  struct hdmi_codec_daifmt;
>  struct hdmi_codec_params;
> @@ -1832,6 +1833,41 @@ struct drm_connector_hdmi {
>  	} infoframes;
>  };
>  
> +/**
> + * struct drm_connector_cec - DRM Connector CEC-related structure
> + */
> +struct drm_connector_cec {
> +	/**
> +	 * @mutex: protects all CEC-related fields
> +	 */
> +	struct mutex mutex;
> +
> +	/**
> +	 * @adap: CEC adapter corresponding to the DRM connector.
> +	 */
> +	struct cec_adapter *adapter;
> +
> +	/**
> +	 * @notifier: CEC notifier corresponding to the DRM connector.
> +	 */
> +	struct cec_notifier *notifier;
> +
> +	/**
> +	 * @adap_unregister: unregister CEC adapter / notifier.
> +	 *
> +	 * The callback to unregister CEC adapter or notifier, so that the core
> +	 * DRM layer doesn't depend on the CEC_CORE.
> +	 */
> +	void (*unregister)(struct drm_connector *connector);
> +
> +	/**
> +	 * @uninit_cec_cb: teardown CEC adapter
> +	 *
> +	 * Perform additional tasks to teardown the CEC adapter.
> +	 */
> +	void (*uninit_cec)(struct drm_connector *connector);
> +};

I'd rather stay consistent with the video and audio support and have the
functions in a separate structure.

Maxime

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