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drm: Add ddc link in sysfs created by drm_connector

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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>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/d470def6cd661b777faeee67b5838a4623c4010e.1564161140.git.andrzej.p@collabora.com
This commit is contained in:
Andrzej Pietrasiewicz 2019-07-26 19:22:55 +02:00 committed by Neil Armstrong
parent 77b8cabf3d
commit e1a29c6c59
2 changed files with 19 additions and 0 deletions
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8
drivers/gpu/drm/drm_sysfs.c
View File

@ -14,6 +14,7 @@
#include <linux/err.h>
#include <linux/export.h>
#include <linux/gfp.h>
#include <linux/i2c.h>
#include <linux/kdev_t.h>
#include <linux/slab.h>
@ -294,6 +295,9 @@ 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 +305,10 @@ 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);

11
include/drm/drm_connector.h
View File

@ -41,6 +41,7 @@ struct drm_property;
struct drm_property_blob;
struct drm_printer;
struct edid;
struct i2c_adapter;
enum drm_connector_force {
DRM_FORCE_UNSPECIFIED,
@ -1311,6 +1312,16 @@ 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