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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

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?

> 
> 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

-- 
Ville Syrjälä
Intel