Registering multiple backlight devices with intel_backlight name will obviously fail, regardless of whether they're two connectors in the same drm device or two different drm devices. It would be preferrable to switch to completely unique names, and sunset the generic intel_backlight name. However, there are apparently users out there that hardcode the name, so the change would break backward compatibility. As a compromise, register the first device with intel_backlight name. In the common case, this is the only backlight device anyway. From the second device on, use card%d-%s-backlight format, for example card0-eDP-2-backlight, to make the name unique. This approach does not preclude us from registering the first device using the same naming scheme in the future. v2: Keep using intel_backlight name for first backlight device Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2794 Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> --- drivers/gpu/drm/i915/display/intel_panel.c | 23 ++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c index 3088677ab8a7..a20761079ae0 100644 --- a/drivers/gpu/drm/i915/display/intel_panel.c +++ b/drivers/gpu/drm/i915/display/intel_panel.c @@ -1401,16 +1401,31 @@ int intel_backlight_device_register(struct intel_connector *connector) else props.power = FB_BLANK_POWERDOWN; - /* - * Note: using the same name independent of the connector prevents - * registration of multiple backlight devices in the driver. - */ name = kstrdup("intel_backlight", GFP_KERNEL); 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) { + 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, "[CONNECTOR:%d:%s] backlight device %s register failed: %ld\n", -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
