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FrontRunner/Toucan-AF: work around AGESA RAM init crashing on reboot 

If you try to reset the system with outb(3,0x92), outb(4,0xcf9) or a
triple-fault it will instead crash with a messy screen.  As the more common
outb(0xFE, 0x64) doesn't work with our setup, Linux will crash whenever you
ask it to reboot.  Closer inspection shows that on a warm boot of Coreboot
agesawrapper_amdinitpost() always fails with error code 7.  Looks like DDR3
re-init goes wrong somehow.  I tried find the reason for this but was
unable to.  I am convinced this is not board specific but a bug in AGESA.

In the end I had to settle for a workaround:  if amdinitpost returns 7 this
patch resets the system harder with outb(0x06, 0x0cf9), after that RAM init
will succeed.  As amdinitpost is early in POST this automatic reset is
quick enough not to be noticable.

I'd perfer a real fix, but that's all I have.

Change-Id: I4763254b489f42a135232e45328ecf0d5c4d961a
Signed-off-by: Jens Rottmann <JRottmann@LiPPERTembedded.de>
Reviewed-on: http://review.coreboot.org/2573
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
This commit is contained in:
Jens Rottmann 2013-03-01 19:01:00 +01:00 committed by Stefan Reinauer
parent 68c9f2bdc5
commit f91c8f290b
2 changed files with 8 additions and 0 deletions
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4
src/mainboard/lippert/frontrunner-af/romstage.c
View File

@ -113,6 +113,10 @@ void cache_as_ram_main(unsigned long bist, unsigned long cpu_init_detectedx)
post_code(0x40);
printk(BIOS_DEBUG, "agesawrapper_amdinitpost ");
val = agesawrapper_amdinitpost ();
/* Reboots with outb(3,0x92), outb(4,0xcf9) or triple-fault all
* hang, looks like DRAM re-init goes wrong, don't know why. */
if (val == 7) /* fatal, amdinitenv below is going to hang */
outb(0x06, 0x0cf9); /* reset system harder instead */
if (val)
printk(BIOS_DEBUG, "error level: %x \n", val);
else

4
src/mainboard/lippert/toucan-af/romstage.c
View File

@ -113,6 +113,10 @@ void cache_as_ram_main(unsigned long bist, unsigned long cpu_init_detectedx)
post_code(0x40);
printk(BIOS_DEBUG, "agesawrapper_amdinitpost ");
val = agesawrapper_amdinitpost ();
/* Reboots with outb(3,0x92), outb(4,0xcf9) or triple-fault all
* hang, looks like DRAM re-init goes wrong, don't know why. */
if (val == 7) /* fatal, amdinitenv below is going to hang */
outb(0x06, 0x0cf9); /* reset system harder instead */
if (val)
printk(BIOS_DEBUG, "error level: %x \n", val);
else