[PATCH] drm/i915/dp: Enable AUX based backlight for HDR

[Borah, Chaitanya Kumar]

Hello Suraj,

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Suraj
> Kandpal
> Sent: Thursday, March 7, 2024 3:59 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: Shankar, Uma <uma.shankar at intel.com>; Nautiyal, Ankit K
> <ankit.k.nautiyal at intel.com>; Kandpal, Suraj <suraj.kandpal at intel.com>
> Subject: [PATCH] drm/i915/dp: Enable AUX based backlight for HDR
> 
> As of now whenerver HDR is switched on we use the PWM to change the
> backlight as opposed to AUX based backlight changes in terms of nits.
> This patch writes to the appropriate DPCD registers to enable aux based
> backlight using values in nits.
> 
> --v2
> -Fix max_cll and max_fall assignment [Jani] -Fix the size sent in
> drm_dpcd_write [Jani]
> 
> --v3
> -Content Luminance needs to be sent only for pre-ICL after that it is directly
> picked up from hdr metadata [Ville]
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> ---
>  .../drm/i915/display/intel_dp_aux_backlight.c | 33 ++++++++++++++-----
>  1 file changed, 25 insertions(+), 8 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 4f58efdc688a..cba7b8f5dad4 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -40,11 +40,6 @@
>  #include "intel_dp.h"
>  #include "intel_dp_aux_backlight.h"
> 
> -/* TODO:
> - * Implement HDR, right now we just implement the bare minimum to bring
> us back into SDR mode so we
> - * can make people's backlights work in the mean time
> - */
> -
>  /*
>   * DP AUX registers for Intel's proprietary HDR backlight interface. We define
>   * them here since we'll likely be the only driver to ever use these.
> @@ -221,7 +216,7 @@ intel_dp_aux_hdr_set_backlight(const struct
> drm_connector_state *conn_state, u32
>  	struct intel_connector *connector = to_intel_connector(conn_state-
> >connector);
>  	struct intel_panel *panel = &connector->panel;
> 
> -	if (panel->backlight.edp.intel.sdr_uses_aux) {
> +	if (panel->backlight.edp.intel.sdr_uses_aux ||
> +conn_state->hdr_output_metadata) {
>  		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
>  	} else {
>  		const u32 pwm_level =
> intel_backlight_level_to_pwm(connector, level); @@ -251,8 +246,15 @@
> intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
>  	}
> 
>  	ctrl = old_ctrl;
> -	if (panel->backlight.edp.intel.sdr_uses_aux) {
> +	if (panel->backlight.edp.intel.sdr_uses_aux ||
> +conn_state->hdr_output_metadata) {
>  		ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
> +
> +		if (conn_state->hdr_output_metadata) {
> +			ctrl |=
> INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE;
> +			ctrl |=
> INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE;
> +			ctrl |=
> INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE;
> +		}
> +
>  		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
>  	} else {
>  		u32 pwm_level = intel_backlight_level_to_pwm(connector,
> level); @@ -292,9 +294,11 @@ intel_dp_aux_hdr_setup_backlight(struct
> intel_connector *connector, enum pipe pi  {
>  	struct drm_i915_private *i915 = to_i915(connector->base.dev);
>  	struct intel_panel *panel = &connector->panel;
> +	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
>  	struct drm_luminance_range_info *luminance_range =
>  		&connector->base.display_info.luminance_range;
>  	int ret;
> +	u8 buf[4];
> 
>  	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] SDR backlight is
> controlled through %s\n",
>  		    connector->base.base.id, connector->base.name, @@ -
> 318,11 +322,24 @@ intel_dp_aux_hdr_setup_backlight(struct intel_connector
> *connector, enum pipe pi
>  		panel->backlight.min = 0;
>  	}
> 
> +	if (DISPLAY_VER(i915) < 11) {
> +		buf[0] = connector-
> >base.hdr_sink_metadata.hdmi_type1.max_cll & 0xFF;
> +		buf[1] = (connector-
> >base.hdr_sink_metadata.hdmi_type1.max_cll & 0xFF00) >> 8;
> +		buf[2] = connector-
> >base.hdr_sink_metadata.hdmi_type1.max_fall & 0xFF;
> +		buf[3] = (connector-
> >base.hdr_sink_metadata.hdmi_type1.max_fall &
> +0xFF00) >> 8;
> +
> +		ret = drm_dp_dpcd_write(&intel_dp->aux,
> INTEL_EDP_HDR_CONTENT_LUMINANCE, buf,
> +					sizeof(buf));
> +		if (ret < 0)
> +			drm_dbg_kms(&i915->drm,
> +				    "Content Luminance DPCD reg write failed,
> err:-%d\n",

Any reason for printing this in negative?

Regards
Chaitanya

> +				    ret);
> +	}
> +
>  	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX HDR
> interface for backlight control (range %d..%d)\n",
>  		    connector->base.base.id, connector->base.name,
>  		    panel->backlight.min, panel->backlight.max);
> 
> -
>  	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector,
> pipe);
>  	panel->backlight.enabled = panel->backlight.level != 0;
> 
> --
> 2.43.2