Commit 4234ea30 authored by Arun R Murthy's avatar Arun R Murthy Committed by Jani Nikula
Browse files

drm/i915/display: avoid warnings when registering dual panel backlight 



Commit 20f85ef8 ("drm/i915/backlight: use unique backlight device
names") added support for multiple backlight devices on dual panel
systems, but did so with error handling on -EEXIST from
backlight_device_register(). Unfortunately, that triggered a warning in
dmesg all the way down from sysfs_add_file_mode_ns() and
sysfs_warn_dup().

Instead of optimistically always attempting to register with the default
name ("intel_backlight", which we have to retain for backward
compatibility), check if a backlight device with the name exists first,
and, if so, use the card and connector based name.

v2: reworked on top of the patch commit 20f85ef8
("drm/i915/backlight: use unique backlight device names")
v3: fixed the ref count leak(Jani N)

Fixes: 20f85ef8 ("drm/i915/backlight: use unique backlight device names")
Signed-off-by: default avatarArun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220808035750.3111046-1-arun.r.murthy@intel.com
parent 4cf05a4d

drivers/gpu/drm/i915/display/intel_backlight.c

+12 −14
Original line number Diff line number Diff line
@@ -972,9 +972,9 @@ int intel_backlight_device_register(struct intel_connector *connector) 
	if (!name)

		return -ENOMEM;



	bd = backlight_device_register(name, connector->base.kdev, connector,

				       &intel_backlight_device_ops, &props);



	bd = backlight_device_get_by_name(name);

	if (bd) {

		put_device(&bd->dev);

		/*

		 * Using the same name independent of the drm device or connector

		 * prevents registration of multiple backlight devices in the
@@ -982,16 +982,14 @@ int intel_backlight_device_register(struct intel_connector *connector) 
		 * compatibility. Use unique names for subsequent backlight devices as a

		 * fallback when the default name already exists.

		 */

	if (IS_ERR(bd) && PTR_ERR(bd) == -EEXIST) {

		kfree(name);

		name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",

				 i915->drm.primary->index, connector->base.name);

		if (!name)

			return -ENOMEM;



	}

	bd = backlight_device_register(name, connector->base.kdev, connector,

				       &intel_backlight_device_ops, &props);

	}



	if (IS_ERR(bd)) {

		drm_err(&i915->drm,