[PATCH 08/13] drm/dp: Modify drm_edp_backlight_set_level

[Murthy, Arun R]

> -----Original Message-----
> From: Kandpal, Suraj <suraj.kandpal at intel.com>
> Sent: Friday, May 9, 2025 10:48 AM
> To: nouveau at lists.freedesktop.org; dri-devel at lists.freedesktop.org; intel-
> xe at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
> Cc: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>; Murthy, Arun R
> <arun.r.murthy at intel.com>; Kandpal, Suraj <suraj.kandpal at intel.com>
> Subject: [PATCH 08/13] drm/dp: Modify drm_edp_backlight_set_level
> 
> Modify drm_edp_backlight_set_level to be able to set the value for register in
> DP_EDP_PANEL_TARGET_LUMINANCE_VALUE. We multiply the level with 1000
> since we get the value in Nits and the register accepts it in milliNits.
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> ---
>  drivers/gpu/drm/display/drm_dp_helper.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
> b/drivers/gpu/drm/display/drm_dp_helper.c
> index b17f9e75d93f..b0688945649b 100644
> --- a/drivers/gpu/drm/display/drm_dp_helper.c
> +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> @@ -3936,20 +3936,28 @@ int drm_edp_backlight_set_level(struct
> drm_dp_aux *aux, const struct drm_edp_bac
>  				u32 level)
>  {
>  	int ret;
> -	u8 buf[2] = { 0 };
> +	unsigned int offset = DP_EDP_BACKLIGHT_BRIGHTNESS_MSB;
> +	u8 buf[3] = { 0 };
> 
>  	/* The panel uses the PWM for controlling brightness levels */
> -	if (!bl->aux_set)
> +	if (!(bl->aux_set || bl->luminance_set))
>  		return 0;
> 
> -	if (bl->lsb_reg_used) {
Can a comment be added to specify the units?

Thanks and Regards,
Arun R Murthy
--------------------

> +	if (bl->luminance_set) {
> +		level = level * 1000;
> +		level &= 0xffffff;
> +		buf[0] = (level & 0x0000ff);
> +		buf[1] = (level & 0x00ff00) >> 8;
> +		buf[2] = (level & 0xff0000) >> 16;
> +		offset = DP_EDP_PANEL_TARGET_LUMINANCE_VALUE;
> +	} else if (bl->lsb_reg_used) {
>  		buf[0] = (level & 0xff00) >> 8;
>  		buf[1] = (level & 0x00ff);
>  	} else {
>  		buf[0] = level;
>  	}
> 
> -	ret = drm_dp_dpcd_write_data(aux,
> DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, buf, sizeof(buf));
> +	ret = drm_dp_dpcd_write_data(aux, offset, buf, sizeof(buf));
>  	if (ret < 0) {
>  		drm_err(aux->drm_dev,
>  			"%s: Failed to write aux backlight level: %d\n",
> --
> 2.34.1