atlas: let AP fully control display backlight

this change removes the EC from the display backlight control logic.
previously, the EC would enable/disable the backlight master enable
directly based on the lid switch.  this turns out to be redundant and
in some cases causes timing violations between backlight enable and
the backlight PWM signal.

the AP already controls the display power load switch
(EN_PP3300_DX_EDP), so when the AP is off, display power (including
the backlight) is also off.  in addition, the AP correctly controls
the backlight using PCH_EDP_BKLTEN.  with this change, we're only
removing the EC's master kill switch for the backlight.

BRANCH=none
BUG=b:129651119,b:128625720
TEST=verified no ill effects on atlas.  EE scoped PWM vs. BL enable.

Change-Id: Ibef9062ce66dfec1363626e674f144a1a3d55b5e
Signed-off-by: Caveh Jalali <caveh@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1566482
Commit-Queue: Caveh Jalali <caveh@google.com>
Tested-by: Caveh Jalali <caveh@google.com>
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
(cherry picked from commit e3c9e42a6475121e07fc5b9372e24af847fecf4b)
Reviewed-on: https://chromium-review.googlesource.com/1585134
Commit-Ready: Caveh Jalali <caveh@google.com>
Reviewed-by: Caveh Jalali <caveh@google.com>

1 files changed, 0 insertions, 2 deletions

diff --git a/board/atlas/board.c b/board/atlas/board.c
index fd38f1cee2..e0350cfd80 100644
--- a/board/atlas/board.c
+++ b/board/atlas/board.c
@@ -545,14 +545,12 @@ void board_set_charge_limit(int port, int supplier, int charge_ma,
 
 static void board_chipset_suspend(void)
 {
-	gpio_set_level(GPIO_ENABLE_BACKLIGHT, 0);
 	gpio_set_level(GPIO_KBD_BL_EN, 0);
 }
 DECLARE_HOOK(HOOK_CHIPSET_SUSPEND, board_chipset_suspend, HOOK_PRIO_DEFAULT);
 
 static void board_chipset_resume(void)
 {
-	gpio_set_level(GPIO_ENABLE_BACKLIGHT, 1);
 	gpio_set_level(GPIO_KBD_BL_EN, 1);
 }
 DECLARE_HOOK(HOOK_CHIPSET_RESUME, board_chipset_resume, HOOK_PRIO_DEFAULT);