On Wed, Apr 28, 2021 at 01:14:29PM +0300, Jani Nikula wrote: > 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.
"intel_backlight" symlink for the first backlight might be an option I guess. Series is Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com> > > v2: Keep using intel_backlight name for first backlight device > > Cc: Ville Syrjälä <ville.syrj...@linux.intel.com> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2794 > Signed-off-by: Jani Nikula <jani.nik...@intel.com> > --- > 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 -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
