From 18537817484580fef1f154cb3fcb2574d3f5a858 Mon Sep 17 00:00:00 2001 From: Arthur Heymans Date: Wed, 28 Dec 2016 21:20:45 +0100 Subject: [PATCH] nb/intel/945gc: Hardcode the integrated graphic frequencies The code to set the igd frequencies is written with the mobile version of the 945 chipset in mind and seems to cause cause strange igd related problems on the desktop versions. Some possible problems are: * on 800MHz fsb CPUs the igd sometimes has artifacts on the screen; * on 800MHz fsb CPU memtest results vary a lot; * since a commit 45e11aa0a5 "Add/Combine Broadwell Chromebooks using variant board scheme" that does not affect this northbridge, the display shows garbage as soon as Linux (4.8) modesets the display. A fix is to hardcode the core display and render clocks to their maximum, potentially also improving graphical performance. Vendor bios on all boards in coreboot with this northbridge have the same value in this PCI config address. TESTED on P5GC-MX (display works fine again in Linux) and user reports of it making GA-945GCM-S2L run more stable. Change-Id: I8b046edbc952631d9b79023e3d385160ff682c24 Signed-off-by: Arthur Heymans Reviewed-on: https://review.coreboot.org/17981 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel Reviewed-by: Nico Huber --- src/northbridge/intel/i945/raminit.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/northbridge/intel/i945/raminit.c b/src/northbridge/intel/i945/raminit.c index a4a1eaf0ca..f9ba37b17b 100644 --- a/src/northbridge/intel/i945/raminit.c +++ b/src/northbridge/intel/i945/raminit.c @@ -3116,8 +3116,14 @@ void sdram_initialize(int boot_path, const u8 *spd_addresses) /* Program PLL settings */ sdram_program_pll_settings(&sysinfo); - /* Program Graphics Frequency */ - sdram_program_graphics_frequency(&sysinfo); + /* + * Program Graphics Frequency + * Set core display and render clock on 945GC to the max + */ + if (IS_ENABLED(CONFIG_NORTHBRIDGE_INTEL_SUBTYPE_I945GM)) + sdram_program_graphics_frequency(&sysinfo); + else + pci_write_config16(PCI_DEV(0, 2, 0), GCFC, 0x0534); /* Program System Memory Frequency */ sdram_program_memory_frequency(&sysinfo);