On Wed, 03 Aug 2022, Arun R Murthy <arun.r.murthy@xxxxxxxxx> wrote:
> The patch with commit 20f85ef89d94 ("drm/i915/backlight: use unique
> backlight device names") already adds support for dual panel backlight
> but with error prints. Since the patch tried to create the backlight
> device with the same name and upon failure will try with a different
> name it leads to failure logs in dmesg inturn getting caught by CI.
>
> This patch alternately will check if the backlight class of same name
> exists, will use a different 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)
>
> Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
> ---
> .../gpu/drm/i915/display/intel_backlight.c | 27 +++++++++----------
> 1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c b/drivers/gpu/drm/i915/display/intel_backlight.c
> index 110fc98ec280..0f93b2ba907b 100644
> --- a/drivers/gpu/drm/i915/display/intel_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_backlight.c
> @@ -971,26 +971,25 @@ 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(bd);
Okay, this is getting tedious.
Please think about why this kfree is wrong.
BR,
Jani.
> 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,
--
Jani Nikula, Intel Open Source Graphics Center
