From nobody Tue Sep 29 13:19:45 2026 Received: from mail.tuxedocomputers.com (mail.tuxedocomputers.com [157.90.84.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9CE063E1681 for ; Fri, 7 Aug 2026 20:07:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=157.90.84.7 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786133248; cv=none; b=UjVQUcumdmTJVWGJOX+/eU/vWFJKlg9Z/bCYuoWl9g660K5fN5jM9p9x3kdxn2ATBo3TQX6Fe8mGLfS8e2rBK+CESQ4Gn+/2c2E0eZS1oY/cNXN/EFMe4j2s4HDdSFZEYk4ZEUrWh1nRLRrhx63H3sQWtOrvJp6FgktjSCFudtc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786133248; c=relaxed/simple; bh=I14M16H5DIx+zUaLN0jBx7Jc/Scfu7vZudbcB10OhLo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JOps0Aeucd4QaKMLsI4GN13ERnaUobv5KJnAlxtr9F5sIAZb5Ba3950K/FjCG6Y9fulNJvVYBAHH6LqhZKlvdMjhSSmPeV1O3xDojmm3cDI6DTXVYn0wXIgDHZFtkO08BqbdfB8TsQOmjIg5OzGn+C5Av2MHt/7BUzb6ZYYHZrk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=tuxedocomputers.com; spf=pass smtp.mailfrom=tuxedocomputers.com; dkim=pass (1024-bit key) header.d=tuxedocomputers.com header.i=@tuxedocomputers.com header.b=hdRMQcG1; arc=none smtp.client-ip=157.90.84.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=tuxedocomputers.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tuxedocomputers.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=tuxedocomputers.com header.i=@tuxedocomputers.com header.b="hdRMQcG1" Received: from wsembach-tuxedo.buero.augsburg.tuxedo.de (host-212-18-30-247.customer.m-online.net [212.18.30.247]) (Authenticated sender: wse@tuxedocomputers.com) by mail.tuxedocomputers.com (Postfix) with ESMTPA id 4C42E2FC004D; Fri, 7 Aug 2026 22:07:20 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tuxedocomputers.com; s=default; t=1786133241; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zcqw3phGqPumtEwKCvYGijd5ryFAPbT280s+LSCI/8c=; b=hdRMQcG1JSMcvMN0AD/lPeaLbjwOhOgCDiK2X/lxC3xbHrFsdeYv6PAAKbdGqHC1ouRHxe FsMDzl+9KPWqQTCRBBWySFrEQV40/cnWvD/6mGTMwvn/AVUH3PcFnD+P1yzxWO6k8vQt9A e2o+JRmZ+G/MRQsEtXGKe+MnGHn30Mk= Authentication-Results: mail.tuxedocomputers.com; auth=pass smtp.auth=wse@tuxedocomputers.com smtp.mailfrom=wse@tuxedocomputers.com From: Werner Sembach To: jani.nikula@linux.intel.com, rodrigo.vivi@intel.com, joonas.lahtinen@linux.intel.com, tursulin@ursulin.net, airlied@gmail.com, simona@ffwll.ch, Suraj Kandpal , Ankit Nautiyal Cc: wse@tuxedocomputers.com, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 1/1] drm/i915/display: Add quirk to force backlight type on some TUXEDO devices Date: Fri, 7 Aug 2026 22:04:30 +0200 Message-ID: <20260807200709.464343-2-wse@tuxedocomputers.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260807200709.464343-1-wse@tuxedocomputers.com> References: <20260807200709.464343-1-wse@tuxedocomputers.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The display backlight on TUXEDO DX1708 and InsanityBook 15 v1 have a broken VBT in the AUO 12701 and AUO 12701 panels, but not others. They are advertising INTEL_BACKLIGHT_DISPLAY_DDI, but are actually failing to use the Intel interface. Adding a fallback to the VESA interface gives these devices a working backlight for both the broken and non broken panel VBTs. Forcing the fallback can already be achieved via a module parameter, but this patch adds a quirk to apply this by default on the mentioned devices. This patch does not actually test for the exact panels as the ID that is used in the intel_dpcd_quirks list is sadly zeroed on the devices, but afaik all these devices use try_intel_interface first anyway so all the quirk does is to add the fallback to try_vesa_interface, so the behaviour on the devices not needing the quirk and fallback should functionally stay the same. Fixes: f30fddb44023 ("Revert "drm/i915/backlight: Remove try_vesa_interface= "") Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/15679 Cc: stable@vger.kernel.org Signed-off-by: Werner Sembach Reviewed-by: Suraj Kandpal --- .../drm/i915/display/intel_dp_aux_backlight.c | 22 ++++++++++++++++- drivers/gpu/drm/i915/display/intel_quirks.c | 24 +++++++++++++++++++ drivers/gpu/drm/i915/display/intel_quirks.h | 1 + 3 files changed, 46 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/driver= s/gpu/drm/i915/display/intel_dp_aux_backlight.c index 266e042e00237..d84def79c4bfb 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -41,6 +41,7 @@ #include "intel_display_types.h" #include "intel_dp.h" #include "intel_dp_aux_backlight.h" +#include "intel_quirks.h" =20 /* * DP AUX registers for Intel's proprietary HDR backlight interface. We de= fine @@ -687,11 +688,30 @@ int intel_dp_aux_init_backlight_funcs(struct intel_co= nnector *connector) struct drm_device *dev =3D connector->base.dev; struct intel_panel *panel =3D &connector->panel; bool try_intel_interface =3D false, try_vesa_interface =3D false; + int enable_dpcd_backlight; + + /* + * Some devices have a broken VBT in some Panels, but not others, + * advertising INTEL_BACKLIGHT_DISPLAY_DDI, but actually failing to use + * the Intel interface. Adding a fallback to the Vesa interface gives + * these devices a working backlight for both the broken and non broken + * panel VBTs. + * + * This fallback can not be made the general default as this has broken + * other devices in the past whose VBT correctly reports + * INTEL_BACKLIGHT_DISPLAY_DDI and whose PWM path is the actual + * backlight control, but whose DPCD optimistically advertises + * DP_EDP_BACKLIGHT_AUX_ENABLE_CAP / _BRIGHTNESS_AUX_SET_CAP. + */ + enable_dpcd_backlight =3D display->params.enable_dpcd_backlight; + if (enable_dpcd_backlight =3D=3D INTEL_DP_AUX_BACKLIGHT_AUTO && + intel_has_dpcd_quirk(intel_dp, QUIRK_ENABLE_DPCD_BACKLIGHT)) + enable_dpcd_backlight =3D INTEL_DP_AUX_BACKLIGHT_ON; =20 /* Check the VBT and user's module parameters to figure out which * interfaces to probe */ - switch (display->params.enable_dpcd_backlight) { + switch (enable_dpcd_backlight) { case INTEL_DP_AUX_BACKLIGHT_OFF: return -ENODEV; case INTEL_DP_AUX_BACKLIGHT_AUTO: diff --git a/drivers/gpu/drm/i915/display/intel_quirks.c b/drivers/gpu/drm/= i915/display/intel_quirks.c index 33245f44c0d50..89d82364ae45d 100644 --- a/drivers/gpu/drm/i915/display/intel_quirks.c +++ b/drivers/gpu/drm/i915/display/intel_quirks.c @@ -100,6 +100,14 @@ static void quirk_disable_psr2(struct intel_display *d= isplay) drm_info(display->drm, "PSR2 support not currently available for this set= up, applying disable PSR2 quirk\n"); } =20 +static void quirk_enable_dpcd_backlight(struct intel_dp *intel_dp) +{ + struct intel_display *display =3D to_intel_display(intel_dp); + + intel_set_dpcd_quirk(intel_dp, QUIRK_ENABLE_DPCD_BACKLIGHT); + drm_info(display->drm, "Applying Enable DPCD Backlight quirk\n"); +} + struct intel_quirk { int device; int subsystem_vendor; @@ -286,6 +294,22 @@ static const struct intel_dpcd_quirk intel_dpcd_quirks= [] =3D { .sink_oui =3D SINK_OUI(0x00, 0x22, 0xb9), .hook =3D quirk_disable_edp_panel_replay, }, + /* TUXEDO InsanityBook 15 v1 */ + { + .device =3D 0x591b, + .subsystem_vendor =3D 0x1558, + .subsystem_device =3D 0x9501, + .sink_oui =3D SINK_OUI(0x38, 0xec, 0x11), + .hook =3D quirk_enable_dpcd_backlight, + }, + /* TUXEDO DX1708 */ + { + .device =3D 0x3e9b, + .subsystem_vendor =3D 0x1558, + .subsystem_device =3D 0x8500, + .sink_oui =3D SINK_OUI(0x38, 0xec, 0x11), + .hook =3D quirk_enable_dpcd_backlight, + }, }; =20 void intel_init_quirks(struct intel_display *display) diff --git a/drivers/gpu/drm/i915/display/intel_quirks.h b/drivers/gpu/drm/= i915/display/intel_quirks.h index 970a4fe52fafc..4996419ae76bd 100644 --- a/drivers/gpu/drm/i915/display/intel_quirks.h +++ b/drivers/gpu/drm/i915/display/intel_quirks.h @@ -23,6 +23,7 @@ enum intel_quirk_id { QUIRK_EDP_LIMIT_RATE_HBR2, QUIRK_DISABLE_EDP_PANEL_REPLAY, QUIRK_DISABLE_PSR2, + QUIRK_ENABLE_DPCD_BACKLIGHT, }; =20 void intel_init_quirks(struct intel_display *display); --=20 2.43.0