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

[Werner Sembach <wse@tuxedocomputers.com>]

Hi,

Am 22.07.25 um 13:40 schrieb Werner Sembach:
> Hi,
>
> Am 15.04.25 um 17:48 schrieb Werner Sembach:
>> Hi,
>>
>> Am 11.04.25 um 20:56 schrieb Ville Syrjälä:
>>> On Fri, Apr 11, 2025 at 05:55:08PM +0200, Werner Sembach wrote:
>>>> 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 device + panel
>>>> combinations.
>>> Why aren't you fixing the VBT to be correct in the first place?
>>
>> I don't have access to the firmware source code and these are quite old 
>> devices so I also can't request a fix from the ODM. Besides: it can be quite 
>> hard to explain to the ODM what exactly the problem is if it doesn't also 
>> affect Windows.
>
> TBH I don't know what VBT stands for, I just assumed it has to to with the 
> displays firmware?
>
> Unlike I wrote in the cover letter we actually still had an affected device in 
> our archives -> the issue persists and the quirk is still necessary.
Hope a gentle bump here is ok
>
> Best Regards,
>
> Werner
>
>>
>> Best regards,
>>
>> Werner Sembach
>>
>>>
>>>> Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
>>>> Cc: stable@vger.kernel.org
>>>> ---
>>>>   .../drm/i915/display/intel_dp_aux_backlight.c | 14 ++++++-
>>>>   drivers/gpu/drm/i915/display/intel_quirks.c   | 42 +++++++++++++++++++
>>>>   drivers/gpu/drm/i915/display/intel_quirks.h   |  1 +
>>>>   3 files changed, 56 insertions(+), 1 deletion(-)
>>>>
>>>> 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 c846ef4acf5b2..0cac04c98a3e3 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
>>>> @@ -34,12 +34,14 @@
>>>>    * for some reason.
>>>>    */
>>>>   +#include <drm/drm_edid.h>
>>>>   #include "i915_utils.h"
>>>>   #include "intel_backlight.h"
>>>>   #include "intel_display_core.h"
>>>>   #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
>>>> @@ -607,11 +609,21 @@ 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;
>>>> +    u32 pnl_id;
>>>>         /* 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_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))
>>>> +            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 8b30e9fd936e7..6f724e5712664 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_quirks.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_quirks.c
>>>> @@ -78,6 +78,12 @@ static void quirk_fw_sync_len(struct intel_dp *intel_dp)
>>>>       drm_info(display->drm, "Applying Fast Wake sync pulse count quirk\n");
>>>>   }
>>>>   +static void quirk_auo_12701_21229_enable_dpcd_backlight(struct 
>>>> intel_display *display)
>>>> +{
>>>> +    intel_set_quirk(display, QUIRK_AUO_12701_21229_ENABLE_DPCD_BACKLIGHT);
>>>> +    drm_info(display->drm, "Applying Display AUO Model 12701 and 21229 
>>>> Enable DPCD Backlight quirk\n");
>>>> +}
>>>> +
>>>>   struct intel_quirk {
>>>>       int device;
>>>>       int subsystem_vendor;
>>>> @@ -118,6 +124,12 @@ static int intel_dmi_no_pps_backlight(const struct 
>>>> dmi_system_id *id)
>>>>       return 1;
>>>>   }
>>>>   +static int intel_dmi_auo_12701_21229_enable_dpcd_backlight(const struct 
>>>> dmi_system_id *id)
>>>> +{
>>>> +    DRM_INFO("Display AUO model 12701 and 21229 DPCD backlight control on 
>>>> %s\n", id->ident);
>>>> +    return 1;
>>>> +}
>>>> +
>>>>   static const struct intel_dmi_quirk intel_dmi_quirks[] = {
>>>>       {
>>>>           .dmi_id_list = &(const struct dmi_system_id[]) {
>>>> @@ -164,6 +176,36 @@ static const struct intel_dmi_quirk intel_dmi_quirks[] 
>>>> = {
>>>>           },
>>>>           .hook = quirk_no_pps_backlight_power_hook,
>>>>       },
>>>> +    {
>>>> +        .dmi_id_list = &(const struct dmi_system_id[]) {
>>>> +            {
>>>> +                .callback = intel_dmi_auo_12701_21229_enable_dpcd_backlight,
>>>> +                .ident = "TUXEDO DX1708",
>>>> +                .matches = {DMI_MATCH(DMI_BOARD_NAME, "N8xEJEK"),
>>>> +                },
>>>> +            },
>>>> +            {
>>>> +                .callback = intel_dmi_auo_12701_21229_enable_dpcd_backlight,
>>>> +                .ident = "TUXEDO InsanityBook 15 v1",
>>>> +                .matches = {DMI_MATCH(DMI_BOARD_NAME, "P95_HP"),
>>>> +                },
>>>> +            },
>>>> +            {
>>>> +                .callback = intel_dmi_auo_12701_21229_enable_dpcd_backlight,
>>>> +                .ident = "TUXEDO InsanityBook 15 v1",
>>>> +                .matches = {DMI_MATCH(DMI_BOARD_NAME, "P95_HR"),
>>>> +                },
>>>> +            },
>>>> +            {
>>>> +                .callback = intel_dmi_auo_12701_21229_enable_dpcd_backlight,
>>>> +                .ident = "TUXEDO InsanityBook 15 v1",
>>>> +                .matches = {DMI_MATCH(DMI_BOARD_NAME, "P95_HP,HR,HQ"),
>>>> +                },
>>>> +            },
>>>> +            { }
>>>> +        },
>>>> +        .hook = quirk_auo_12701_21229_enable_dpcd_backlight,
>>>> +    },
>>>>   };
>>>>     static struct intel_quirk intel_quirks[] = {
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_quirks.h 
>>>> b/drivers/gpu/drm/i915/display/intel_quirks.h
>>>> index cafdebda75354..38bdbd65d7efb 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_quirks.h
>>>> +++ b/drivers/gpu/drm/i915/display/intel_quirks.h
>>>> @@ -20,6 +20,7 @@ enum intel_quirk_id {
>>>>       QUIRK_LVDS_SSC_DISABLE,
>>>>       QUIRK_NO_PPS_BACKLIGHT_POWER_HOOK,
>>>>       QUIRK_FW_SYNC_LEN,
>>>> +    QUIRK_AUO_12701_21229_ENABLE_DPCD_BACKLIGHT,
>>>>   };
>>>>     void intel_init_quirks(struct intel_display *display);
>>>> -- 
>>>> 2.43.0