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Message-ID: <f0028617-3d82-4d03-9ed1-4722b2e30bec@tuxedocomputers.com>
Date: Mon, 9 Feb 2026 23:22:06 +0100
From: Werner Sembach <wse@...edocomputers.com>
To: "Kandpal, Suraj" <suraj.kandpal@...el.com>,
Jani Nikula <jani.nikula@...ux.intel.com>,
"Vivi, Rodrigo" <rodrigo.vivi@...el.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>
Cc: "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
"intel-xe@...ts.freedesktop.org" <intel-xe@...ts.freedesktop.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/i915/display: Add quirk to force backlight type on
some TUXEDO devices
Hi Suraj,
Am 29.01.26 um 05:23 schrieb Kandpal, Suraj:
>> Subject: [PATCH v2] drm/i915/display: Add quirk to force backlight type on
>> some TUXEDO devices
>>
>> The display backlight on TUXEDO DX1708 and InsanityBook 15 v1 with panels
>> AUO 12701 and AUO 12701 must be forced to
>> INTEL_DP_AUX_BACKLIGHT_ON to be able to control the brightness.
>>
>> This could already be archived 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.
> Hi Sembach,
>
> Thanks for the patch. I would recommend opening a gitlab issue with all the details
> (platform, edp version etc), Along with dmesg logs with drm.debug set to 0x10e and kernel
> Version mentioned . So we can root cause this properly and determine is an actual quirk is required or not.
> Use can use this as a guide https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html
Done: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15679
Best Regards,
Werner
>
> Regards,
> Suraj Kandpal
>
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Werner Sembach <wse@...edocomputers.com>
>> ---
>> .../drm/i915/display/intel_dp_aux_backlight.c | 9 ++++++-
>> drivers/gpu/drm/i915/display/intel_quirks.c | 25 ++++++++++++++++++-
>> drivers/gpu/drm/i915/display/intel_quirks.h | 1 +
>> 3 files changed, 33 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>> b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>> index 0a3a3f6a5f9d8..bbdfa142d084d 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"
>>
>> /*
>> * DP AUX registers for Intel's proprietary HDR backlight interface. We define
>> @@ -661,11 +662,17 @@ int intel_dp_aux_init_backlight_funcs(struct
>> intel_connector *connector)
>> struct drm_device *dev = connector->base.dev;
>> struct intel_panel *panel = &connector->panel;
>> bool try_intel_interface = false, try_vesa_interface = false;
>> + int enable_dpcd_backlight;
>>
>> /* Check the VBT and user's module parameters to figure out which
>> * interfaces to probe
>> */
>> - 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_dpcd_quirk(intel_dp,
>> QUIRK_ENABLE_DPCD_BACKLIGHT))
>> + enable_dpcd_backlight = INTEL_DP_AUX_BACKLIGHT_ON;
>> +
>> + 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 d2e16b79d6be1..df20930f73f75 100644
>> --- a/drivers/gpu/drm/i915/display/intel_quirks.c
>> +++ b/drivers/gpu/drm/i915/display/intel_quirks.c
>> @@ -86,6 +86,14 @@ static void quirk_edp_limit_rate_hbr2(struct
>> intel_display *display)
>> drm_info(display->drm, "Applying eDP Limit rate to HBR2 quirk\n"); }
>>
>> +static void quirk_enable_dpcd_backlight(struct intel_dp *intel_dp) {
>> + struct intel_display *display = 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;
>> @@ -251,7 +259,22 @@ static const struct intel_dpcd_quirk
>> intel_dpcd_quirks[] = {
>> .sink_oui = SINK_OUI(0x38, 0xec, 0x11),
>> .hook = quirk_fw_sync_len,
>> },
>> -
>> + /* TUXEDO InsanityBook 15 v1 */
>> + {
>> + .device = 0x591b,
>> + .subsystem_vendor = 0x1558,
>> + .subsystem_device = 0x9501,
>> + .sink_oui = SINK_OUI(0x38, 0xec, 0x11),
>> + .hook = quirk_enable_dpcd_backlight,
>> + },
>> + /* TUXEDO DX1708 */
>> + {
>> + .device = 0x3e9b,
>> + .subsystem_vendor = 0x1558,
>> + .subsystem_device = 0x8500,
>> + .sink_oui = SINK_OUI(0x38, 0xec, 0x11),
>> + .hook = quirk_enable_dpcd_backlight,
>> + },
>> };
>>
>> 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 06da0e286c67c..686f306ab4472 100644
>> --- a/drivers/gpu/drm/i915/display/intel_quirks.h
>> +++ b/drivers/gpu/drm/i915/display/intel_quirks.h
>> @@ -21,6 +21,7 @@ enum intel_quirk_id {
>> QUIRK_NO_PPS_BACKLIGHT_POWER_HOOK,
>> QUIRK_FW_SYNC_LEN,
>> QUIRK_EDP_LIMIT_RATE_HBR2,
>> + QUIRK_ENABLE_DPCD_BACKLIGHT,
>> };
>>
>> void intel_init_quirks(struct intel_display *display);
>> --
>> 2.43.0
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