Re: [PATCH v4 01/23] drm: Include ddc adapter pointer in struct drm_connector

From: "Ville Syrjälä" <ville.syrjala-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: Andrzej Pietrasiewicz
	<andrzej.p-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
Cc: "Y.C. Chen" <yc_chen-SAlXDmAnmOAqDJ6do+/SaQ@public.gmane.org>,
	"Heiko Stübner" <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>,
	"Sam Ravnborg" <sam-uyr5N9Q2VtJg9hUCZPvPmw@public.gmane.org>,
	"Neil Armstrong"
	<narmstrong-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>,
	"Maxime Ripard"
	<maxime.ripard-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org>,
	"Joonas Lahtinen"
	<joonas.lahtinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	"Liviu Dudau" <liviu.dudau-5wv7dgnIgG8@public.gmane.org>,
	dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	"Douglas Anderson"
	<dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	"Andrzej Hajda" <a.hajda-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	"Thierry Reding"
	<thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	"Laurent Pinchart"
	<Laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>,
	"Benjamin Gaignard"
	<benjamin.gaignard-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	kernel-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org,
	"Fabio Estevam"
	<festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	"David (ChunMing) Zhou"
	<David1.Zhou-5C7GfCeVMHo@public.gmane.org>,
	"Joonyoung Shim"
	<jy0922.shim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	"Vincent Abriou" <vincent.abriou-qxv4g6HH51o@public.gmane.org>,
	"Rob Clark" <robdclark-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	"Krzysztof Kozlowski"
	<krzk-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Jonathan Hunter"
	<jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH v4 01/23] drm: Include ddc adapter pointer in struct drm_connector
Date: Thu, 11 Jul 2019 15:00:17 +0300	[thread overview]
Message-ID: <20190711120017.GU5942__4977.01970614202$1562871353$gmane$org@intel.com> (raw)
In-Reply-To: <5957ae96ee20eed5cfcb8a9619e2f61d71fe227e.1562843413.git.andrzej.p-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>

On Thu, Jul 11, 2019 at 01:26:28PM +0200, Andrzej Pietrasiewicz wrote:
> Add generic code which creates symbolic links in sysfs, pointing to ddc
> interface used by a particular video output. For example:
> 
> ls -l /sys/class/drm/card0-HDMI-A-1/ddc
> lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \
> 	-> ../../../../soc/13880000.i2c/i2c-2
> 
> This makes it easy for user to associate a display with its ddc adapter
> and use e.g. ddcutil to control the chosen monitor.
> 
> This patch adds an i2c_adapter pointer to struct drm_connector. Particular
> drivers can then use it instead of using their own private instance. If a
> connector contains a ddc, then create a symbolic link in sysfs.
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
> ---
>  drivers/gpu/drm/drm_sysfs.c |  7 +++++++
>  include/drm/drm_connector.h | 11 +++++++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index ad10810bc972..26d359b39785 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -294,6 +294,9 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
>  	/* Let userspace know we have a new connector */
>  	drm_sysfs_hotplug_event(dev);
>  
> +	if (connector->ddc)
> +		return sysfs_create_link(&connector->kdev->kobj,
> +				 &connector->ddc->dev.kobj, "ddc");
>  	return 0;
>  }
>  
> @@ -301,6 +304,10 @@ void drm_sysfs_connector_remove(struct drm_connector *connector)
>  {
>  	if (!connector->kdev)
>  		return;
> +
> +	if (connector->ddc)
> +		sysfs_remove_link(&connector->kdev->kobj, "ddc");
> +
>  	DRM_DEBUG("removing \"%s\" from sysfs\n",
>  		  connector->name);
>  
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index ca745d9feaf5..1ad3d1d54ba7 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -23,6 +23,7 @@
>  #ifndef __DRM_CONNECTOR_H__
>  #define __DRM_CONNECTOR_H__
>  
> +#include <linux/i2c.h>

struct i2c_adapter;
would suffice.

>  #include <linux/list.h>
>  #include <linux/llist.h>
>  #include <linux/ctype.h>
> @@ -1308,6 +1309,16 @@ struct drm_connector {
>  	 * [0]: progressive, [1]: interlaced
>  	 */
>  	int audio_latency[2];
> +
> +	/**
> +	 * @ddc: associated ddc adapter.
> +	 * A connector usually has its associated ddc adapter. If a driver uses
> +	 * this field, then an appropriate symbolic link is created in connector
> +	 * sysfs directory to make it easy for the user to tell which i2c
> +	 * adapter is for a particular display.
> +	 */
> +	struct i2c_adapter *ddc;
> +
>  	/**
>  	 * @null_edid_counter: track sinks that give us all zeros for the EDID.
>  	 * Needed to workaround some HW bugs where we get all 0s
> -- 
> 2.17.1

-- 
Ville Syrjälä
Intel
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