linux-kernel - Re: [PATCH 1/1] drm/i915/display: Add quirk to force backlight type on some TUXEDO devices

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Message-ID: <2531c69c-2b56-40db-8344-62a4613b2641@tuxedocomputers.com>
Date: Fri, 14 Nov 2025 19:43:41 +0100
From: Werner Sembach <wse@...edocomputers.com>
To: jani.nikula@...ux.intel.com, rodrigo.vivi@...el.com,
 joonas.lahtinen@...ux.intel.com, tursulin@...ulin.net, airlied@...il.com,
 simona@...ll.ch
Cc: intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] drm/i915/display: Add quirk to force backlight type
 on some TUXEDO devices

Am 11.04.25 um 17:55 schrieb Werner Sembach:
> <snip>
> -	switch (display->params.enable_dpcd_backlight) {
> +	enable_dpcd_backlight = display->params.enable_dpcd_backlight;
> +	if (enable_dpcd_backlight == INTEL_DP_AUX_BACKLIGHT_AUTO &&
> +	    intel_has_quirk(display, QUIRK_AUO_12701_21229_ENABLE_DPCD_BACKLIGHT)) {
> +		pnl_id = drm_edid_get_panel_id(panel->fixed_edid);
> +		if (pnl_id == drm_edid_encode_panel_id('A', 'U', 'O', 0x319d) ||
> +		    pnl_id == drm_edid_encode_panel_id('A', 'U', 'O', 0x52ed))

So I looked into this patch again to build a v2 and found "static const struct 
intel_dpcd_quirk intel_dpcd_quirks[]" in 
drivers/gpu/drm/i915/display/intel_quirks.c which sounds like it can select 
quirks based on panels, making this pnl_id check obsolete.

But I now wasted half a day trying to find out how I can get the SINK_OUI and 
SINK_DEVICE_ID out of a device.

Is there some way to read that from sysfs or debugfs?

> <snip>