Peter Stuge ([email protected]) just uploaded a new patch set to gerrit, which you 
can find at http://review.coreboot.org/590

-gerrit

commit faa6bebeaa2dbdacb9333d20e5a2f6f52b21a3f0
Author: Peter Stuge <[email protected]>
Date:   Fri Jan 27 22:17:09 2012 +0100

    northbridge/intel/i945: CHECK_SLFRCS_ON_RESUME Kconfig option
    
    Originally brought up by Sven Schnelle in March 2011
    http://patchwork.coreboot.org/patch/2801/
    http://www.coreboot.org/pipermail/coreboot/2011-March/064277.html
    
    On some mainboards it may be neccessary to reset early during resume
    from S3 if the SLFRCS register indicates that a memory channel is not
    guaranteed to be in self-refresh.
    
    On other mainboards, such as Lenovo X60 and T60, the check always
    creates false positives, effectively making it impossible to resume.
    
    The SLFRCS register is documented on page 197 of
    
    Mobile IntelĀ® 945 Express Chipset Family Datasheet
    Document Number: 309219-006
    
    which is publically available, and the register indicates if a memory
    channel is guaranteed to be in self-refresh mode (if bit = 1), or that
    a memory channel *may or may not be* in self-refresh mode (if bit = 0).
    
    The register can thus only be used to positively learn that memory is
    in self-refresh. It is not known for sure that memory is *not* in
    self-refresh. The register is reset by the PWROK signal, which *should*
    go low during S3, and go high again when resuming, so it is unsurprising
    that SLFRCS has already been cleared when we read the register.
    
    Sven's measurements of the CKE signal on a ThinkPad shows that memory
    remains in self-refresh indefinitely, until coreboot re-initializes the
    memory controller, even when SLFRCS bits were = 0.
    
    Boards which require a warm reset when SLFRCS bits are cleared must now
    explicitly enable the check in the mainboard Kconfig file.
    
    This commit selects the new option in all existing i945 mainboards.
    A follow-up commit will remove the option for ThinkPads.
    
    Change-Id: I02320675efb8fde05c371ef243ba5093a4da6d11
    Signed-off-by: Peter Stuge <[email protected]>
---
 src/mainboard/getac/p470/Kconfig       |    1 +
 src/mainboard/ibase/mb899/Kconfig      |    1 +
 src/mainboard/intel/d945gclf/Kconfig   |    1 +
 src/mainboard/kontron/986lcd-m/Kconfig |    1 +
 src/mainboard/lenovo/t60/Kconfig       |    1 +
 src/mainboard/lenovo/x60/Kconfig       |    1 +
 src/mainboard/roda/rk886ex/Kconfig     |    1 +
 src/northbridge/intel/i945/Kconfig     |    9 +++++++++
 src/northbridge/intel/i945/raminit.c   |    4 ++--
 9 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/mainboard/getac/p470/Kconfig b/src/mainboard/getac/p470/Kconfig
index ec30859..6ca11e5 100644
--- a/src/mainboard/getac/p470/Kconfig
+++ b/src/mainboard/getac/p470/Kconfig
@@ -23,6 +23,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_MFCPGA478
        select NORTHBRIDGE_INTEL_I945GM
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SOUTHBRIDGE_TI_PCIXX12
        select SUPERIO_SMSC_FDC37N972
diff --git a/src/mainboard/ibase/mb899/Kconfig 
b/src/mainboard/ibase/mb899/Kconfig
index 02ccfab..ac87466 100644
--- a/src/mainboard/ibase/mb899/Kconfig
+++ b/src/mainboard/ibase/mb899/Kconfig
@@ -5,6 +5,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_MFCPGA478
        select NORTHBRIDGE_INTEL_I945GM
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SUPERIO_WINBOND_W83627EHG
        select BOARD_HAS_FADT
diff --git a/src/mainboard/intel/d945gclf/Kconfig 
b/src/mainboard/intel/d945gclf/Kconfig
index 2b0161c..efc8025 100644
--- a/src/mainboard/intel/d945gclf/Kconfig
+++ b/src/mainboard/intel/d945gclf/Kconfig
@@ -23,6 +23,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_441
        select NORTHBRIDGE_INTEL_I945GC
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SUPERIO_SMSC_LPC47M15X
        select BOARD_HAS_FADT
diff --git a/src/mainboard/kontron/986lcd-m/Kconfig 
b/src/mainboard/kontron/986lcd-m/Kconfig
index 01e4b2f..ec5c073 100644
--- a/src/mainboard/kontron/986lcd-m/Kconfig
+++ b/src/mainboard/kontron/986lcd-m/Kconfig
@@ -5,6 +5,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_MFCPGA478
        select NORTHBRIDGE_INTEL_I945GM
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SUPERIO_WINBOND_W83627THG
        select BOARD_HAS_FADT
diff --git a/src/mainboard/lenovo/t60/Kconfig b/src/mainboard/lenovo/t60/Kconfig
index d1abcf6..1e4afd1 100644
--- a/src/mainboard/lenovo/t60/Kconfig
+++ b/src/mainboard/lenovo/t60/Kconfig
@@ -5,6 +5,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_MFCPGA478
        select NORTHBRIDGE_INTEL_I945GM
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SUPERIO_NSC_PC87382
        select SUPERIO_NSC_PC87384
diff --git a/src/mainboard/lenovo/x60/Kconfig b/src/mainboard/lenovo/x60/Kconfig
index 69f83a8..64a3761 100644
--- a/src/mainboard/lenovo/x60/Kconfig
+++ b/src/mainboard/lenovo/x60/Kconfig
@@ -5,6 +5,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_MFCPGA478
        select NORTHBRIDGE_INTEL_I945GM
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SOUTHBRIDGE_RICOH_RL5C476
        select SUPERIO_NSC_PC87382
diff --git a/src/mainboard/roda/rk886ex/Kconfig 
b/src/mainboard/roda/rk886ex/Kconfig
index 7dfcc7d..d5de7dc 100644
--- a/src/mainboard/roda/rk886ex/Kconfig
+++ b/src/mainboard/roda/rk886ex/Kconfig
@@ -5,6 +5,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
        select ARCH_X86
        select CPU_INTEL_SOCKET_MFCPGA478
        select NORTHBRIDGE_INTEL_I945GM
+       select CHECK_SLFRCS_ON_RESUME
        select SOUTHBRIDGE_INTEL_I82801GX
        select SOUTHBRIDGE_TI_PCI7420
        select SUPERIO_SMSC_LPC47N227
diff --git a/src/northbridge/intel/i945/Kconfig 
b/src/northbridge/intel/i945/Kconfig
index 9ba47da..42cc7ce 100644
--- a/src/northbridge/intel/i945/Kconfig
+++ b/src/northbridge/intel/i945/Kconfig
@@ -53,4 +53,13 @@ config MAXIMUM_SUPPORTED_FREQUENCY
          the board supports, despite what the chipset should be
          capable of.
 
+config CHECK_SLFRCS_ON_RESUME
+       def_bool n
+       help
+         On some boards it may be neccessary to hard reset early
+         during resume from S3 if the SLFRCS register indicates that
+         a memory channel is not guaranteed to be in self-refresh.
+         On other boards the check always creates a false positive,
+         effectively making it impossible to resume.
+
 endif
diff --git a/src/northbridge/intel/i945/raminit.c 
b/src/northbridge/intel/i945/raminit.c
index a7fbaa4..d92c006 100644
--- a/src/northbridge/intel/i945/raminit.c
+++ b/src/northbridge/intel/i945/raminit.c
@@ -294,8 +294,8 @@ static void sdram_detect_errors(struct sys_info *sysinfo)
        reg8 |= (1<<7);
        pci_write_config8(PCI_DEV(0, 0x1f, 0), 0xa2, reg8);
 
-       /* clear self refresh if not wake-up from suspend */
-       if (sysinfo->boot_path != 2) {
+       /* clear self refresh status if check is disabled or not a resume */
+       if (!CONFIG_CHECK_SLFRCS_ON_RESUME || sysinfo->boot_path != 2) {
                MCHBAR8(0xf14) |= 3;
        } else {
                /* Validate self refresh config */

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