diff options
Diffstat (limited to 'config/coreboot/default/patches/0042-mb-dell-e6400-Use-100-MHz-reference-clock-for-displa.patch')
| -rw-r--r-- | config/coreboot/default/patches/0042-mb-dell-e6400-Use-100-MHz-reference-clock-for-displa.patch | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/config/coreboot/default/patches/0042-mb-dell-e6400-Use-100-MHz-reference-clock-for-displa.patch b/config/coreboot/default/patches/0042-mb-dell-e6400-Use-100-MHz-reference-clock-for-displa.patch new file mode 100644 index 00000000..991dcf44 --- /dev/null +++ b/config/coreboot/default/patches/0042-mb-dell-e6400-Use-100-MHz-reference-clock-for-displa.patch @@ -0,0 +1,52 @@ +From b42ca30081b25cbabfb2659adca9d935ef3a8399 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 3/3] 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 +++ + src/northbridge/intel/gm45/Kconfig | 4 ++++ + 2 files changed, 7 insertions(+) + +diff --git a/src/mainboard/dell/e6400/Kconfig b/src/mainboard/dell/e6400/Kconfig +index 417d95fd5d..6fe1b1c456 100644 +--- a/src/mainboard/dell/e6400/Kconfig ++++ b/src/mainboard/dell/e6400/Kconfig +@@ -19,6 +19,9 @@ 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" + +diff --git a/src/northbridge/intel/gm45/Kconfig b/src/northbridge/intel/gm45/Kconfig +index 8059e7ee80..5df5a93296 100644 +--- a/src/northbridge/intel/gm45/Kconfig ++++ b/src/northbridge/intel/gm45/Kconfig +@@ -14,6 +14,10 @@ config NORTHBRIDGE_INTEL_GM45 + + if NORTHBRIDGE_INTEL_GM45 + ++config INTEL_GMA_DPLL_REF_FREQ ++ int ++ default 96000000 ++ + config VBOOT + select VBOOT_STARTS_IN_BOOTBLOCK + +-- +2.39.2 + |