Change in coreboot[master]: soc/rockchip/rk3399/sdram: Use rank_mask in WDQL training

[Moritz Fischer (Code Review)]

Attention is currently required from: Julius Werner.
Moritz Fischer has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/50888 )

Change subject: soc/rockchip/rk3399/sdram: Use rank_mask in WDQL training
......................................................................

soc/rockchip/rk3399/sdram: Use rank_mask in WDQL training

Add rank_mask based on the rank number and iterate based on that rather
than iterating all values.

Note: LPDDR4 uses a different rank mask.

Signed-off-by: Moritz Fischer 
Change-Id: I1bff9d20d3d66984c49073aa21212708039d578f
---
M src/soc/rockchip/rk3399/sdram.c
1 file changed, 11 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/88/50888/1

diff --git a/src/soc/rockchip/rk3399/sdram.c b/src/soc/rockchip/rk3399/sdram.c
index efa820a..194197a 100644
--- a/src/soc/rockchip/rk3399/sdram.c
+++ b/src/soc/rockchip/rk3399/sdram.c
@@ -847,12 +847,22 @@
 {
    u32 *denali_pi = rk3399_ddr_pi[channel]->denali_pi;
    u32 rank = params->ch[channel].rank;
+	u32 rank_mask;
    u32 i, tmp;

/* clear interrupt,PI_175 PI_INT_ACK:WR:0:17 */
    write32(&denali_pi[175], 0x00003f7c);

-	for (i = 0; i < rank; i++) {
+	/* required rank mask is different for LPDDR4 */
+	if (params->dramtype == LPDDR4)
+		rank_mask = (rank == 1) ? 0x5 : 0xf;
+	else
+		rank_mask = (rank == 1) ? 0x1 : 0x3;
+
+	for (i = 0; i < 4; i++) {
+		if (!(rank_mask & (1 << i)))
+			continue;
+
    	select_per_cs_training_index(channel, i);
    	/*
    	 * disable PI_WDQLVL_VREF_EN before wdq leveling?