lbmk/config/coreboot/dell/patches/0010-mb-dell-e6400-Use-100-...

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From c35d431a0f1b326b18cd5bbb7d1d49e67d3309bd Mon Sep 17 00:00:00 2001
From: Nicholas Chin <nic.c3.14@gmail.com>
Date: Mon, 20 May 2024 10:24:16 -0600
Subject: [PATCH] mb/dell/e6400: Use 100 MHz reference clock for display
The E6400 uses a 100 MHz reference clock for spread spectrum support on
LVDS, whereas libgfxinit previously assumed a 96 MHz input clock. For
the more common 1280 x 800 display panels, the numerical error was not
large enough to cause noticable issues, but the actual pixel clock
frequency derived from a 100 MHz reference using PLL configs calculated
assuming a 96 MHz reference was not close enough for 1440 x 900 panels,
which require a much higher pixel clock. This resulted in a garbled
display in the pre-OS graphics environment provided by libgfxinit.
Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
---
src/mainboard/dell/e6400/Kconfig | 3 +++
1 file changed, 3 insertions(+)
diff --git a/src/mainboard/dell/e6400/Kconfig b/src/mainboard/dell/e6400/Kconfig
index 034de4be2b..4cb16af697 100644
--- a/src/mainboard/dell/e6400/Kconfig
+++ b/src/mainboard/dell/e6400/Kconfig
@@ -17,6 +17,9 @@ config BOARD_SPECIFIC_OPTIONS
select INTEL_GMA_HAVE_VBT
select EC_DELL_MEC5035
+config INTEL_GMA_DPLL_REF_FREQ
+ default 100000000
+
config MAINBOARD_DIR
default "dell/e6400"
--
2.45.1