On Wed, 24 Aug 2022, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > On machins without an i915 opregion the acpi_video driver immediately > probes the ACPI video bus and used to also immediately register > acpi_video# backlight devices when supported. > > Once the drm/kms driver then loaded later and possibly registered > a native backlight device then the drivers/acpi/video_detect.c code > unregistered the acpi_video0 device to avoid there being 2 backlight > devices (when acpi_video_get_backlight_type()==native). > > This means that userspace used to briefly see 2 devices and the > disappearing of acpi_video0 after a brief time confuses the systemd > backlight level save/restore code, see e.g.: > https://bbs.archlinux.org/viewtopic.php?id=269920 > > To fix this the ACPI video code has been modified to make backlight class > device registration a separate step, relying on the drm/kms driver to > ask for the acpi_video backlight registration after it is done setting up > its native backlight device. > > Add a call to the new acpi_video_register_backlight() after the i915 calls > acpi_video_register() (after setting up the i915 opregion) so that the > acpi_video backlight devices get registered on systems where the i915 > native backlight device is not registered. > > Changes in v2: > -Only call acpi_video_register_backlight() when a panel is detected > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > --- > drivers/gpu/drm/i915/display/intel_display.c | 8 ++++++++ > drivers/gpu/drm/i915/display/intel_panel.c | 3 +++ > drivers/gpu/drm/i915/i915_drv.h | 2 ++ > 3 files changed, 13 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c > index 6103b02c081f..2bb53efdb149 100644 > --- a/drivers/gpu/drm/i915/display/intel_display.c > +++ b/drivers/gpu/drm/i915/display/intel_display.c > @@ -9088,6 +9088,14 @@ void intel_display_driver_register(struct drm_i915_private *i915) > /* Must be done after probing outputs */ > intel_opregion_register(i915); > acpi_video_register(); > + /* > + * Only call this if i915 is driving the internal panel. If the internal > + * panel is not driven by i915 then another GPU driver may still register > + * a native backlight driver later and this should only be called after > + * any native backlights have been registered. > + */ > + if (i915->have_panel) > + acpi_video_register_backlight(); Apologies for procrastinating the review. Please let's not add new flags like have_panel to i915; we're trying to clean it up instead. The code here needs to iterate over the connectors to decide. Maybe better abstracted a function. BR, Jani. > > intel_audio_init(i915); > > diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c > index 237a40623dd7..4536c527f50c 100644 > --- a/drivers/gpu/drm/i915/display/intel_panel.c > +++ b/drivers/gpu/drm/i915/display/intel_panel.c > @@ -646,8 +646,11 @@ intel_panel_mode_valid(struct intel_connector *connector, > > int intel_panel_init(struct intel_connector *connector) > { > + struct drm_i915_private *dev_priv = to_i915(connector->base.dev); > struct intel_panel *panel = &connector->panel; > > + dev_priv->have_panel = true; > + > intel_backlight_init_funcs(panel); > > drm_dbg_kms(connector->base.dev, > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index 69ce6db6a7c1..14b0dcaf25c2 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -756,6 +756,8 @@ struct drm_i915_private { > > bool ipc_enabled; > > + bool have_panel; > + > struct intel_audio_private audio; > > struct i915_pmu pmu; -- Jani Nikula, Intel Open Source Graphics Center
