Stefan Reinauer (stefan.reinauer@coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9497
-gerrit
commit 4ccab29ab722a5afea92095975a16b4fa0852493 Author: Duncan Laurie dlaurie@chromium.org Date: Tue Jan 20 07:53:27 2015 -0800
broadwell: Add configuration for tuning VR for C-state operations
Add some configuration options that allow tuning the VR for C-state settings that may be able to reduce noise.
- Add option to enable slow VR ramp rate for C-state exit - Add variable to configure the minimum C6/C7 voltage
BUG=chrome-os-partner:34771 BRANCH=broadwell TEST=build and boot on samus
Change-Id: I01445d62fbfcf200b787b924d8d72685819a4715 Signed-off-by: Stefan Reinauer reinauer@chromium.org Original-Commit-Id: ed8f355e60292c82791817ae31bff58ac2390a72 Original-Change-Id: I8af75b69c8b55d3e210170ee96f8e22c2fd76374 Original-Signed-off-by: Duncan Laurie dlaurie@chromium.org Original-Reviewed-on: https://chromium-review.googlesource.com/241950 Original-Reviewed-by: Aaron Durbin adurbin@chromium.org --- src/soc/intel/broadwell/chip.h | 22 ++++++++++++++++++++++ src/soc/intel/broadwell/cpu.c | 20 ++++++++++++++++---- 2 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/src/soc/intel/broadwell/chip.h b/src/soc/intel/broadwell/chip.h index 703c865..77c517d 100644 --- a/src/soc/intel/broadwell/chip.h +++ b/src/soc/intel/broadwell/chip.h @@ -130,6 +130,28 @@ struct soc_intel_broadwell_config { /* Enable S0iX support */ int s0ix_enable;
+ /* + * Minimum voltage for C6/C7 state: + * 0x67 = 1.6V (full swing) + * ... + * 0x79 = 1.7V + * ... + * 0x83 = 1.8V (no swing) + */ + int vr_cpu_min_vid; + + /* + * Set slow VR ramp rate on C-state exit: + * 0 = Fast VR ramp rate / 2 + * 1 = Fast VR ramp rate / 4 + * 2 = Fast VR ramp rate / 8 + * 3 = Fast VR ramp rate / 16 + */ + int vr_slow_ramp_rate_set; + + /* Enable slow VR ramp rate */ + int vr_slow_ramp_rate_enable; + /* Deep SX enable */ int deep_sx_enable_ac; int deep_sx_enable_dc; diff --git a/src/soc/intel/broadwell/cpu.c b/src/soc/intel/broadwell/cpu.c index b227e0d..9073241 100644 --- a/src/soc/intel/broadwell/cpu.c +++ b/src/soc/intel/broadwell/cpu.c @@ -180,6 +180,8 @@ static u32 pcode_mailbox_read(u32 command)
static void initialize_vr_config(void) { + device_t dev = SA_DEV_ROOT; + config_t *conf = dev->chip_info; msr_t msr;
printk(BIOS_DEBUG, "Initializing VR config.\n"); @@ -203,17 +205,27 @@ static void initialize_vr_config(void) msr.hi |= (0x200 << (40 - 32)); /* 1.0 */ /* Set IOUT_OFFSET to 0. */ msr.hi &= ~0xff; - /* Set exit ramp rate to fast. */ - msr.hi |= (1 << (50 - 32)); /* Set entry ramp rate to slow. */ msr.hi &= ~(1 << (51 - 32)); /* Enable decay mode on C-state entry. */ msr.hi |= (1 << (52 - 32)); - /* Set the slow ramp rate to be fast ramp rate / 4 */ + /* Set the slow ramp rate */ msr.hi &= ~(0x3 << (53 - 32)); - msr.hi |= (0x01 << (53 - 32)); + /* Configure the C-state exit ramp rate. */ + if (conf->vr_slow_ramp_rate_enable) { + /* Configured slow ramp rate. */ + msr.hi |= ((conf->vr_slow_ramp_rate_set & 0x3) << (53 - 32)); + /* Set exit ramp rate to slow. */ + msr.hi &= ~(1 << (50 - 32)); + } else { + /* Fast ramp rate / 4. */ + msr.hi |= (0x01 << (53 - 32)); + /* Set exit ramp rate to fast. */ + msr.hi |= (1 << (50 - 32)); + } /* Set MIN_VID (31:24) to allow CPU to have full control. */ msr.lo &= ~0xff000000; + msr.lo |= (conf->vr_cpu_min_vid & 0xff) << 24; wrmsr(MSR_VR_MISC_CONFIG, msr);
/* Configure VR_MISC_CONFIG2 MSR. */