[coreboot-gerrit] New patch to review for coreboot: mainboard/asus/kgpe-d16: Limit HT speed to 2.6GHz

[Timothy Pearson (tpearson@raptorengineeringinc.com)]

Timothy Pearson (tpearson at raptorengineeringinc.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/12064

-gerrit

commit d1da757a9774e719d63e8a7f46900134db699bff
Author: Timothy Pearson <tpearson at raptorengineeringinc.com>
Date:   Thu Sep 3 17:39:51 2015 -0500

    mainboard/asus/kgpe-d16: Limit HT speed to 2.6GHz
    
    The CPU <--> CPU HT wiring on this board has only been validated
    to 2.6GHz.  While higher frequencies appear to function initially,
    and in fact function when only one CPU package is installed, dual
    CPU package systems will lock up after around 6 - 12 hours of uptime
    due to presumed HT link errors at the higher (>= 2.8GHz) HT clocks.
    
    If applications are not being used that stress the coherent fabric,
    then the uptime before hang may be much longer.  Users attempting
    to overclock the HT links are advised to "burn in test" the HT links
    by running memtester locked to a node with no local memory installed.
    
    Change-Id: I8fae90c67aa0e8b103e9b8906dea50d1e92ea5a9
    Signed-off-by: Timothy Pearson <tpearson at raptorengineeringinc.com>
---
 src/mainboard/asus/kgpe-d16/romstage.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/mainboard/asus/kgpe-d16/romstage.c b/src/mainboard/asus/kgpe-d16/romstage.c
index 6b5d801..61b3f09 100644
--- a/src/mainboard/asus/kgpe-d16/romstage.c
+++ b/src/mainboard/asus/kgpe-d16/romstage.c
@@ -349,6 +349,11 @@ void cache_as_ram_main(unsigned long bist, unsigned long cpu_init_detectedx)
 
 	struct sys_info *sysinfo = &sysinfo_car;
 
+	/* Limit the maximum HT speed to 2.6GHz to prevent lockups
+	 * due to HT CPU <--> CPU wiring not being validated to 3.2GHz
+	 */
+	sysinfo->ht_link_cfg.ht_speed_limit = 2600;
+
 	uint32_t bsp_apicid = 0, val;
 	uint8_t byte;
 	msr_t msr;