drm_edp_backlight_disable(9)

📦 version 7.3.1, in nixpkgs unstable

💅 drm_edp_backlight_disable — a page from the Kernel API Manual ✨

okay so bestie, we're in the Kernel API Manual today and the star of the show is literally drm_edp_backlight_disable(9). she's a little function, she turns off a backlight, and she has opinions about which panels she'll do that for. let's get into it 🎀

🌸 NAME

drm_edp_backlight_disable — Disable an eDP backlight using DPCD, if supported 💡

like, "if supported" is doing SO much work in that sentence, and we will be discussing.

✨ SYNOPSIS

int drm_edp_backlight_disable (struct drm_dp_aux *aux , const struct drm_edp_backlight_info *bl );

yep that's the whole vibe. two args, one int coming back at you 🫶

🦋 ARGUMENTS

  • aux — The DP AUX channel to use. this is your lane to talk to the panel, bestie 🛣️
  • bl — Backlight capability info from drm_edp_backlight_init. basically the little info packet that tells you what this panel can and can't do 💖

🔥 DESCRIPTION

so what does she actually do? This function handles disabling DPCD backlight controls on a panel over AUX. that's it. that's the job. and honestly? she ate. 👑

but here's the tea, and you NEED to hear it ☕: certain panels do not support being enabled or disabled via DPCD. instead they require that the driver handle enabling/disabling the panel through implementation-specific means using the EDP_BL_PWR GPIO. like, the panel said "not my thing, do it yourself."

For such panels, drm_edp_backlight_info.aux_enable will be set to false, this function becomes a no-op, and the driver is expected to handle powering the panel off using the EDP_BL_PWR GPIO.

lowkey important: if aux_enable is false, calling this does absolutely nothing and that's by design, not a bug. the driver has to do the EDP_BL_PWR GPIO thing itself. don't come for her 🙈

⭐ RETURN

  • 0 on success or no-op ✅
  • negative error code on failure 😭

that's it. no grey area, no "it depends" — zero or negative, pick your fighter.

💜 SEE ALSO

bestie. sit down. this list is LONG and we are not skipping a single one of them, because they're all family 🫶

Kernel file ./drivers/gpu/drm/display/drm_dp_helper.c dp helpers(9), drm_dp_phy_name(9), drm_dp_lttpr_wake_timeout_setup(9), dp helpers(9), drm_dp_dpcd_probe(9), drm_dp_dpcd_set_powered(9), drm_dp_dpcd_set_probe(9), drm_dp_dpcd_read(9), drm_dp_dpcd_write(9), drm_dp_dpcd_read_link_status(9), drm_dp_dpcd_read_phy_link_status(9), drm_dp_link_power_up(9), drm_dp_link_power_down(9), drm_dp_dpcd_write_payload(9), drm_dp_dpcd_clear_payload(9), drm_dp_dpcd_poll_act_handled(9), drm_dp_downstream_is_type(9), drm_dp_downstream_is_tmds(9), drm_dp_send_real_edid_checksum(9), drm_dp_read_dpcd_caps(9), drm_dp_read_downstream_info(9), drm_dp_downstream_max_dotclock(9), drm_dp_downstream_max_tmds_clock(9), drm_dp_downstream_min_tmds_clock(9), drm_dp_downstream_max_bpc(9), drm_dp_downstream_420_passthrough(9), drm_dp_downstream_444_to_420_conversion(9), drm_dp_downstream_rgb_to_ycbcr_conversion(9), drm_dp_downstream_mode(9), drm_dp_downstream_id(9), drm_dp_downstream_debug(9), drm_dp_subconnector_type(9), drm_dp_set_subconnector_property(9), drm_dp_read_sink_count_cap(9), drm_dp_read_sink_count(9), drm_dp_remote_aux_init(9), drm_dp_aux_init(9), drm_dp_aux_register(9), drm_dp_aux_unregister(9), drm_dp_psr_setup_time(9), drm_dp_start_crc(9), drm_dp_stop_crc(9), drm_dp_read_desc(9), drm_dp_dump_lttpr_desc(9), drm_dp_dsc_sink_bpp_incr(9), drm_dp_dsc_slice_count_to_mask(9), drm_dp_dsc_sink_slice_count_mask(9), drm_dp_dsc_sink_max_slice_count(9), drm_dp_dsc_sink_line_buf_depth(9), drm_dp_dsc_sink_supported_input_bpcs(9), drm_dp_dsc_sink_max_slice_throughput(9), drm_dp_dsc_branch_max_overall_throughput(9), drm_dp_dsc_branch_max_line_width(9), drm_dp_read_lttpr_common_caps(9), drm_dp_read_lttpr_phy_caps(9), drm_dp_lttpr_count(9), drm_dp_lttpr_max_link_rate(9), drm_dp_lttpr_set_transparent_mode(9), drm_dp_lttpr_init(9), drm_dp_lttpr_max_lane_count(9), drm_dp_lttpr_voltage_swing_level_3_supported(9), drm_dp_lttpr_pre_emphasis_level_3_supported(9), drm_dp_get_phy_test_pattern(9), drm_dp_set_phy_test_pattern(9), drm_dp_as_sdp_supported(9), drm_dp_vsc_sdp_supported(9), drm_dp_vsc_sdp_pack(9), drm_dp_get_pcon_max_frl_bw(9), drm_dp_pcon_frl_prepare(9), drm_dp_pcon_is_frl_ready(9), drm_dp_pcon_frl_configure_1(9), drm_dp_pcon_frl_configure_2(9), drm_dp_pcon_reset_frl_config(9), drm_dp_pcon_frl_enable(9), drm_dp_pcon_hdmi_link_active(9), drm_dp_pcon_hdmi_link_mode(9), drm_dp_pcon_hdmi_frl_link_error_count(9), drm_dp_pcon_pps_default(9), drm_dp_pcon_pps_override_buf(9), drm_edp_backlight_set_level(9), drm_edp_backlight_enable(9), drm_edp_backlight_init(9), drm_panel_dp_aux_backlight(9), drm_dp_link_symbol_cycles(9), drm_dp_bw_overhead(9), drm_dp_bw_channel_coding_efficiency(9), drm_dp_max_dprx_data_rate(9)

and that's the page bestie!! 🧚💖

sign-off time, because the source and the date deserve a shoutout too: this one lives over in ./drivers/gpu/drm/display and it's stamped October 2026. iconic of her honestly. go turn off a backlight responsibly, ily, bye 🎀✨💅

📦 where this page comes from