53 lines
1.7 KiB
Diff
53 lines
1.7 KiB
Diff
From b42ca30081b25cbabfb2659adca9d935ef3a8399 Mon Sep 17 00:00:00 2001
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From: Nicholas Chin <nic.c3.14@gmail.com>
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Date: Mon, 20 May 2024 10:24:16 -0600
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Subject: [PATCH 3/3] mb/dell/e6400: Use 100 MHz reference clock for display
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The E6400 uses a 100 MHz reference clock for spread spectrum support on
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LVDS, whereas libgfxinit previously assumed a 96 MHz input clock. For
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the more common 1280 x 800 display panels, the numerical error was not
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large enough to cause noticable issues, but the actual pixel clock
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frequency derived from a 100 MHz reference using PLL configs calculated
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assuming a 96 MHz reference was not close enough for 1440 x 900 panels,
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which require a much higher pixel clock. This resulted in a garbled
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display in the pre-OS graphics environment provided by libgfxinit.
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Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
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---
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src/mainboard/dell/e6400/Kconfig | 3 +++
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src/northbridge/intel/gm45/Kconfig | 4 ++++
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2 files changed, 7 insertions(+)
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diff --git a/src/mainboard/dell/e6400/Kconfig b/src/mainboard/dell/e6400/Kconfig
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index 417d95fd5d..6fe1b1c456 100644
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--- a/src/mainboard/dell/e6400/Kconfig
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+++ b/src/mainboard/dell/e6400/Kconfig
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@@ -19,6 +19,9 @@ config BOARD_SPECIFIC_OPTIONS
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select INTEL_GMA_HAVE_VBT
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select EC_DELL_MEC5035
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+config INTEL_GMA_DPLL_REF_FREQ
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+ default 100000000
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+
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config MAINBOARD_DIR
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default "dell/e6400"
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diff --git a/src/northbridge/intel/gm45/Kconfig b/src/northbridge/intel/gm45/Kconfig
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index 8059e7ee80..5df5a93296 100644
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--- a/src/northbridge/intel/gm45/Kconfig
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+++ b/src/northbridge/intel/gm45/Kconfig
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@@ -14,6 +14,10 @@ config NORTHBRIDGE_INTEL_GM45
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if NORTHBRIDGE_INTEL_GM45
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+config INTEL_GMA_DPLL_REF_FREQ
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+ int
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+ default 96000000
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+
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config VBOOT
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select VBOOT_STARTS_IN_BOOTBLOCK
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--
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2.39.2
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