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nb/intel/x4x: Fix underclocking of 800MHz DDR2 RAM 

Previously, any 800MHz DIMMs were being slowed to 667MHz
for no reason other than there was a bug in the maximum
frequency detection code for the MCH.

Change-Id: Id6c6c88c4a40631f6caf52f536a939a43cb3faf1
Signed-off-by: Damien Zammit <damien@zamaudio.com>
Reviewed-on: https://review.coreboot.org/15257
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
This commit is contained in:
Damien Zammit 2016-06-18 23:57:43 +10:00 committed by Kyösti Mälkki
parent dc54270210
commit 9ae0985328
1 changed files with 20 additions and 13 deletions
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33
src/northbridge/intel/x4x/raminit.c
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@ -264,11 +264,13 @@ static u8 msbpos(u8 val) //Reverse
static void mchinfo_ddr2(struct sysinfo *s) static void mchinfo_ddr2(struct sysinfo *s)
{ {
u8 capablefreq, maxfreq;
const u32 eax = cpuid_ext(0x04, 0).eax; const u32 eax = cpuid_ext(0x04, 0).eax;
s->cores = ((eax >> 26) & 0x3f) + 1; s->cores = ((eax >> 26) & 0x3f) + 1;
printk(BIOS_WARNING, "%d CPU cores\n", s->cores); printk(BIOS_WARNING, "%d CPU cores\n", s->cores);
u32 capid = pci_read_config16(PCI_DEV(0,0,0), 0xe8); u32 capid = pci_read_config16(PCI_DEV(0, 0, 0), 0xe8);
if (!(capid & (1<<(79-64)))) { if (!(capid & (1<<(79-64)))) {
printk(BIOS_WARNING, "iTPM enabled\n"); printk(BIOS_WARNING, "iTPM enabled\n");
} }
@ -282,7 +284,19 @@ static void mchinfo_ddr2(struct sysinfo *s)
printk(BIOS_WARNING, "AMT enabled\n"); printk(BIOS_WARNING, "AMT enabled\n");
} }
s->max_ddr2_mhz = (capid & (1<<(53-32)))?667:800; maxfreq = MEM_CLOCK_800MHz;
capablefreq = (u8)((pci_read_config16(PCI_DEV(0, 0, 0), 0xea) >> 4) & 0x3f);
capablefreq &= 0x7;
if (capablefreq)
maxfreq = capablefreq + 1;
if (maxfreq > MEM_CLOCK_800MHz)
maxfreq = MEM_CLOCK_800MHz;
if (maxfreq < MEM_CLOCK_667MHz)
maxfreq = MEM_CLOCK_667MHz;
s->max_ddr2_mhz = (maxfreq == MEM_CLOCK_800MHz) ? 800 : 667;
printk(BIOS_WARNING, "Capable of DDR2 of %d MHz or lower\n", s->max_ddr2_mhz); printk(BIOS_WARNING, "Capable of DDR2 of %d MHz or lower\n", s->max_ddr2_mhz);
if (!(capid & (1<<(48-32)))) { if (!(capid & (1<<(48-32)))) {
@ -317,19 +331,11 @@ static void sdram_detect_ram_speed(struct sysinfo *s)
break; break;
} }
// Find RAM speed // Max RAM speed
maxfreq = (u8) ((pci_read_config16(PCI_DEV(0,0,0), 0xea) >> 4) & 0x3f);
if (s->spd_type == DDR2) { if (s->spd_type == DDR2) {
// Limit frequency for MCH // Choose max memory frequency for MCH as previously detected
maxfreq &= 0x7; freq = (s->max_ddr2_mhz == 800) ? MEM_CLOCK_800MHz : MEM_CLOCK_667MHz;
freq = MEM_CLOCK_800MHz;
if (maxfreq) {
freq = maxfreq;
}
if (freq > MEM_CLOCK_800MHz) {
freq = MEM_CLOCK_800MHz;
}
// Detect a common CAS latency // Detect a common CAS latency
commoncas = 0xff; commoncas = 0xff;
@ -411,6 +417,7 @@ static void sdram_detect_ram_speed(struct sysinfo *s)
} else { // DDR3 } else { // DDR3
// Limit frequency for MCH // Limit frequency for MCH
maxfreq = (s->max_ddr2_mhz == 800) ? MEM_CLOCK_800MHz : MEM_CLOCK_667MHz;
maxfreq >>= 3; maxfreq >>= 3;
freq = MEM_CLOCK_1333MHz; freq = MEM_CLOCK_1333MHz;
if (maxfreq) { if (maxfreq) {