Re: [PATCH] drm/i915: add disable_edp module parameter to skip phantom eDP init

[Jani Nikula]

On Tue, 30 Jun 2026, mei.fan.liou@xxxxxxxxx wrote:
> From: "LIOU, Mei Fan" <mei.fan.liou@xxxxxxxxx>
>
> Some platforms have BIOS/VBT that declares an eDP panel present while
> no physical panel is connected. This causes intel_edp_init_connector()
> to spend ~6 seconds waiting on PPS power sequencer and AUX channel
> timeouts before failing gracefully.

Which platforms? This should not be the case.

> Introduce a new boolean module parameter 'disable_edp' (default: false)
> that allows users to skip eDP connector initialization entirely. When
> set, the driver logs an informational message and returns false early
> from intel_edp_init_connector(), bypassing all PPS/AUX probing.

I'm fine with adding module parameters for *debugging*. I'm not fine
with adding module parameters for regular use cases. If there are issues
out there, they should be root caused and fixed, worst case with a
quirk, but roughly never with a new module parameter.

You can also disable connectors using the video= parameter and connector
name, e.g. video=eDP-1:d or something. Making this work (if it doesn't)
should be preferred over adding new module parameters. And even here,
root causing and fixing is preferred.

> This is modeled after the existing 'disable_display' parameter and
> is intended as a workaround for headless or display-less deployments
> where the BIOS incorrectly advertises an internal panel.

"headless" and "display-less" are super ambiguous, given the amount of
possible alternatives. You might not have display IP at all, or you
could have everything except a display connected, or everything in
between. But VBT advertizing eDP but it not being connected is not a
scenario that we should have, and either the VBT or the whole setup is
bonkers.

Please file a bug as described at [1], and be sure to attach the dmesg
with debugs, and the VBT.


BR,
Jani.


[1] https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html


>
> Signed-off-by: LIOU, Mei Fan <mei.fan.liou@xxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/display/intel_display_params.c | 3 +++
>  drivers/gpu/drm/i915/display/intel_display_params.h | 1 +
>  drivers/gpu/drm/i915/display/intel_dp.c             | 7 +++++++
>  3 files changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c b/drivers/gpu/drm/i915/display/intel_display_params.c
> index 2aed110c5b09..8d47d19b1667 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_params.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_params.c
> @@ -102,6 +102,9 @@ intel_display_param_named_unsafe(force_reset_modeset_test, bool, 0400,
>  intel_display_param_named(disable_display, bool, 0400,
>  	"Disable display (default: false)");
>  
> +intel_display_param_named(disable_edp, bool, 0400,
> +	"Disable eDP panel init, skips PPS/AUX probing when VBT declares eDP but no panel is present (default: false)");
> +
>  intel_display_param_named(verbose_state_checks, bool, 0400,
>  	"Enable verbose logs (ie. WARN_ON()) in case of unexpected hw state conditions.");
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h b/drivers/gpu/drm/i915/display/intel_display_params.h
> index b95ecf728daa..98ab0d753dab 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_params.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_params.h
> @@ -41,6 +41,7 @@ struct drm_printer;
>  	param(bool, load_detect_test, false, 0600) \
>  	param(bool, force_reset_modeset_test, false, 0600) \
>  	param(bool, disable_display, false, 0400) \
> +	param(bool, disable_edp, false, 0400) \
>  	param(bool, verbose_state_checks, true, 0400) \
>  	param(bool, nuclear_pageflip, false, 0400) \
>  	param(bool, enable_dp_mst, true, 0600) \
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 85d3aa3b9894..c6293a1b3840 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -7214,6 +7214,13 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
>  	if (!intel_dp_is_edp(intel_dp))
>  		return true;
>  
> +	if (display->params.disable_edp) {
> +		drm_info(display->drm,
> +			 "[ENCODER:%d:%s] eDP disabled by module parameter, skipping init\n",
> +			 encoder->base.base.id, encoder->base.name);
> +		return false;
> +	}
> +
>  	/*
>  	 * On IBX/CPT we may get here with LVDS already registered. Since the
>  	 * driver uses the only internal power sequencer available for both

-- 
Jani Nikula, Intel