New patch to review for coreboot: nb/intel/sandybridge/raminit: support calling dram_freq multiple times

[Patrick Rudolph]

Patrick Rudolph ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/14174

-gerrit

commit 7d39de9348d5faab015f27879dbb078a834b6922
Author: Patrick Rudolph <[e-mail]>
Date:   Sat Mar 26 17:20:02 2016 +0100

    nb/intel/sandybridge/raminit: support calling dram_freq multiple times
    
    The PLL will never lock if the requested frequency is already set.
    As the fallback may request the same frequency again exit early
    to prevent a hang.
    
    Test system:
     * Gigabyte GA-B75M-D3H
     * Intel Pentium CPU G2130
    
    Change-Id: I625b2956346d8c50cca84def6190c076bf99dbec
    Signed-off-by: Patrick Rudolph <[e-mail]>
---
 src/northbridge/intel/sandybridge/raminit.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/northbridge/intel/sandybridge/raminit.c b/src/northbridge/intel/sandybridge/raminit.c
index f6d082f..d0b48e2 100644
--- a/src/northbridge/intel/sandybridge/raminit.c
+++ b/src/northbridge/intel/sandybridge/raminit.c
@@ -810,6 +810,17 @@ static void dram_freq(ramctr_timing * ctrl)
 		/* Frequency mulitplier.  */
 		u32 FRQ = get_FRQ(ctrl->tCK);
 
+		/* The PLL will never lock if the required frequency is
+		 * already set. Exit early to prevent a system hang.
+		 */
+		reg1 = MCHBAR32(0x5e04);
+		val2 = (u8) reg1;
+		if (val2 >= FRQ) {
+			printk(BIOS_DEBUG, "MCU frequency is set at : %d MHz\n",
+			       (1000 << 8) / ctrl->tCK);
+			return;
+		}
+
 		/* Step 2 - Select frequency in the MCU */
 		reg1 = FRQ;
 		reg1 |= 0x80000000;	// set running bit