[coreboot-gerrit] Change in coreboot[master]: nb/intel/sandybridge: Remove spurious writes to IOSAV BW mask

[Angel Pons (Code Review)]

Angel Pons has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/47621 )

Change subject: nb/intel/sandybridge: Remove spurious writes to IOSAV BW mask
......................................................................

nb/intel/sandybridge: Remove spurious writes to IOSAV BW mask

The byte-wise error mask only needs to be set for certain corner cases
in read MPR training. Thus, minimize writes to this register.

Tested on Asus P8H61-M PRO, still boots.

Change-Id: I0bb8d99ad60c4964f896d303878e5982ae1dcdbe
Signed-off-by: Angel Pons 
---
M src/northbridge/intel/sandybridge/raminit_common.c
1 file changed, 4 insertions(+), 23 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/21/47621/1

diff --git a/src/northbridge/intel/sandybridge/raminit_common.c b/src/northbridge/intel/sandybridge/raminit_common.c
index e93ce0a..886177d 100644
--- a/src/northbridge/intel/sandybridge/raminit_common.c
+++ b/src/northbridge/intel/sandybridge/raminit_common.c
@@ -1423,9 +1423,7 @@
    FOR_ALL_POPULATED_CHANNELS {
    	program_timings(ctrl, channel);
    }
-	FOR_ALL_POPULATED_CHANNELS FOR_ALL_LANES {
-		MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
-	}
+
    return 0;
 }

@@ -1978,7 +1976,7 @@

int write_training(ramctr_timing *ctrl)
 {
-	int channel, slotrank, lane;
+	int channel, slotrank;
    int err;

FOR_ALL_POPULATED_CHANNELS
@@ -1992,10 +1990,6 @@

printram("CPF\n");

-	FOR_ALL_POPULATED_CHANNELS FOR_ALL_LANES {
-		MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
-	}
-
    FOR_ALL_POPULATED_CHANNELS {
    	fill_pattern0(ctrl, channel, 0xaaaaaaaa, 0x55555555);
    }
@@ -2015,9 +2009,6 @@
    FOR_ALL_POPULATED_CHANNELS
    	program_timings(ctrl, channel);

-	FOR_ALL_POPULATED_CHANNELS FOR_ALL_LANES {
-		MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
-	}
    return 0;
 }

@@ -2294,6 +2285,7 @@

fill_pattern0(ctrl, channel, 0, 0);
    FOR_ALL_LANES {
+		MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
    	MCHBAR32(IOSAV_By_BW_SERROR_C_ch(channel, lane));
    }

@@ -2357,10 +2349,6 @@
    toggle_io_reset();

FOR_ALL_POPULATED_CHANNELS {
-		FOR_ALL_LANES {
-			MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
-		}
-
    	find_predefined_pattern(ctrl, channel);

fill_pattern0(ctrl, channel, 0, 0xffffffff);
@@ -2539,9 +2527,6 @@
    FOR_ALL_POPULATED_CHANNELS
    	program_timings(ctrl, channel);

-	FOR_ALL_POPULATED_CHANNELS FOR_ALL_LANES {
-		MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
-	}
    return 0;
 }

@@ -3048,7 +3033,7 @@

void restore_timings(ramctr_timing *ctrl)
 {
-	int channel, lane;
+	int channel;

FOR_ALL_POPULATED_CHANNELS {
    	const union tc_rap_reg tc_rap = {
@@ -3069,10 +3054,6 @@
    	wait_for_iosav(channel);
    }

-	FOR_ALL_POPULATED_CHANNELS FOR_ALL_LANES {
-		MCHBAR32(IOSAV_By_BW_MASK_ch(channel, lane)) = 0;
-	}
-
    FOR_ALL_POPULATED_CHANNELS
    	MCHBAR32_OR(TC_RWP_ch(channel), 1 << 27);