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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 <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/14174
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
This commit is contained in:
Patrick Rudolph 2016-03-26 17:20:02 +01:00 committed by Martin Roth
parent 2ccb74b6e9
commit 9c9bde3aa3
1 changed files with 11 additions and 0 deletions
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11
src/northbridge/intel/sandybridge/raminit.c
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@ -810,6 +810,17 @@ static void dram_freq(ramctr_timing * ctrl)
/* Frequency mulitplier. */ /* Frequency mulitplier. */
u32 FRQ = get_FRQ(ctrl->tCK); 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 */ /* Step 2 - Select frequency in the MCU */
reg1 = FRQ; reg1 = FRQ;
reg1 |= 0x80000000; // set running bit reg1 |= 0x80000000; // set running bit