From 2c4e19f873f4a389c2a557a84909cf4b78d3525a Mon Sep 17 00:00:00 2001 From: Arun R Murthy Date: Mon, 8 Aug 2022 09:27:50 +0530 Subject: [PATCH] drm/i915/display: avoid warnings when registering dual panel backlight Commit 20f85ef89d94 ("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 20f85ef89d94 ("drm/i915/backlight: use unique backlight device names") v3: fixed the ref count leak(Jani N) Fixes: 20f85ef89d94 ("drm/i915/backlight: use unique backlight device names") Signed-off-by: Arun R Murthy Signed-off-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20220808035750.3111046-1-arun.r.murthy@intel.com (cherry picked from commit 4234ea30051200fc6016de10e4d58369e60b38f1) Signed-off-by: Rodrigo Vivi --- drivers/gpu/drm/i915/display/intel_backlight.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c b/drivers/gpu/drm/i915/display/intel_backlight.c index 110fc98..9314464 100644 --- a/drivers/gpu/drm/i915/display/intel_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_backlight.c @@ -971,26 +971,24 @@ 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); - - /* - * Using the same name independent of the drm device or connector - * prevents registration of multiple backlight devices in the - * driver. However, we need to use the default name for backward - * 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) { + 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 + * driver. However, we need to use the default name for backward + * compatibility. Use unique names for subsequent backlight devices as a + * fallback when the default name already exists. + */ 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); } + bd = backlight_device_register(name, connector->base.kdev, connector, + &intel_backlight_device_ops, &props); if (IS_ERR(bd)) { drm_err(&i915->drm, -- 2.7.4