From db1ca86bf6bb326383f7b3688326cf6418646dd9 Mon Sep 17 00:00:00 2001 From: Mario Scheithauer Date: Tue, 12 Sep 2023 08:21:50 +0200 Subject: [PATCH] mb/siemens/mc_ehl3: Enable PWM passthrough mode on PTN3460 The connected panel on this mainboard gets the PWM frequency directly from the Elkhart Lake CPU. The PWM controls the brightness of the backlight. Therefore, it is necessary to activate the PWM passthrough mode in the PTN3460 eDP-to-LVDS bridge (see PTN3460 Programming Guide - 5. Configuration Registers). Link to PTN3460 Programming Guide: https://web.archive.org/web/20230908074244/https://www.nxp.com/docs/en/application-note/AN11128.pdf BUG=none TEST=Boot into Linux and change the brightness of the screen Change-Id: Ia0a329426e585b6243c8888806befbe4f6ec2998 Signed-off-by: Mario Scheithauer Reviewed-on: https://review.coreboot.org/c/coreboot/+/77856 Tested-by: build bot (Jenkins) Reviewed-by: Jan Samek --- src/mainboard/siemens/mc_ehl/variants/mc_ehl3/lcd_panel.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/mainboard/siemens/mc_ehl/variants/mc_ehl3/lcd_panel.c b/src/mainboard/siemens/mc_ehl/variants/mc_ehl3/lcd_panel.c index a4985c1c21..0d189a34e2 100644 --- a/src/mainboard/siemens/mc_ehl/variants/mc_ehl3/lcd_panel.c +++ b/src/mainboard/siemens/mc_ehl/variants/mc_ehl3/lcd_panel.c @@ -90,6 +90,8 @@ enum cb_err mainboard_ptn3460_config(struct ptn_3460_config *cfg) cfg->t5_delay = 0x01; /* Enable backlight control. */ cfg->backlight_ctrl = 0x00; + /* Enable PWMI passthrough mode. */ + cfg->pin_cfg_ctrl1 = 0x10; return CB_SUCCESS; }