[coreboot-gerrit] New patch to review for coreboot: c80abbf broadwell: Turn off panel backlight in S5 SMI handler

[Stefan Reinauer (stefan.reinauer@coreboot.org)]

Stefan Reinauer (stefan.reinauer at coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9490

-gerrit

commit c80abbffcbb73610eddb9f3b58e18657719a73e4
Author: Duncan Laurie <dlaurie at chromium.org>
Date:   Wed Jan 14 17:33:00 2015 -0800

    broadwell: Turn off panel backlight in S5 SMI handler
    
    In order for some panels to meet spec when the system is put
    into S5 by way of power button during firmware (i.e. not by
    the OS) then it needs to turn off the backlight and give it
    time to turn off before going into S5.
    
    If the OS properly sequences the panel down then the backlight
    enable bit will not be set in this step and nothing will happen.
    
    BUG=chrome-os-partner:33994
    BRANCH=broadwell
    TEST=build and boot on samus
    
    Change-Id: Ic86f388218f889b1fe690cc1bfc5c3e233e95115
    Signed-off-by: Stefan Reinauer <reinauer at chromium.org>
    Original-Commit-Id: e3c9c131a87bae380e1fd3f96c9ad780441add56
    Original-Change-Id: I43c5aee8e32768fc9e82790c9f7ceda0ed17ed13
    Original-Signed-off-by: Duncan Laurie <dlaurie at chromium.org>
    Original-Reviewed-on: https://chromium-review.googlesource.com/240852
    Original-Reviewed-by: Shawn N <shawnn at chromium.org>
---
 src/soc/intel/broadwell/smihandler.c | 43 ++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/soc/intel/broadwell/smihandler.c b/src/soc/intel/broadwell/smihandler.c
index 5004a6a..0374d15 100644
--- a/src/soc/intel/broadwell/smihandler.c
+++ b/src/soc/intel/broadwell/smihandler.c
@@ -36,6 +36,7 @@
 #include <soc/rcba.h>
 #include <soc/smm.h>
 #include <soc/xhci.h>
+#include <device/i915_reg.h>
 
 static u8 smm_initialized = 0;
 
@@ -109,6 +110,45 @@ static void busmaster_disable_on_bus(int bus)
         }
 }
 
+/*
+ * Turn off the backlight if it is on, and wait for the specified
+ * backlight off delay.  This will allow panel power timings to meet
+ * spec and prevent brief garbage on the screen when turned off
+ * during firmware with power button triggered SMI.
+ */
+static void backlight_off(void)
+{
+	uint32_t reg_base;
+	uint32_t pp_ctrl;
+	uint32_t bl_off_delay;
+
+	reg_base = pci_read_config32(SA_DEV_IGD, PCI_BASE_ADDRESS_0) & ~0xf;
+
+	/* Check if backlight is enabled */
+	pp_ctrl = read32(reg_base + PCH_PP_CONTROL);
+	if (!(pp_ctrl & EDP_BLC_ENABLE))
+		return;
+
+	/* Enable writes to this register */
+	pp_ctrl &= ~PANEL_UNLOCK_MASK;
+	pp_ctrl |= PANEL_UNLOCK_REGS;
+
+	/* Turn off backlight */
+	pp_ctrl &= ~EDP_BLC_ENABLE;
+
+	write32(reg_base + PCH_PP_CONTROL, pp_ctrl);
+	read32(reg_base + PCH_PP_CONTROL);
+
+	/* Read backlight off delay in 100us units */
+	bl_off_delay = read32(reg_base + PCH_PP_OFF_DELAYS);
+	bl_off_delay &= PANEL_LIGHT_OFF_DELAY_MASK;
+	bl_off_delay *= 100;
+
+	/* Wait for backlight to turn off */
+	udelay(bl_off_delay);
+
+	printk(BIOS_INFO, "Backlight turned off\n");
+}
 
 static void southbridge_smi_sleep(void)
 {
@@ -170,6 +210,9 @@ static void southbridge_smi_sleep(void)
 	case SLP_TYP_S5:
 		printk(BIOS_DEBUG, "SMI#: Entering S5 (Soft Power off)\n");
 
+		/* Turn off backlight if needed */
+		backlight_off();
+
 		/* Disable all GPE */
 		disable_all_gpe();