bios/sdram: changes to ease manual read window selection

diff --git a/litex/soc/software/bios/sdram.c b/litex/soc/software/bios/sdram.c
index b55f13f7a7d3b90e7861e740b62c6454814f0faf..fbe3a27e086babbc5fd83e22269f98b0b288b0ef 100644 (file)
--- a/litex/soc/software/bios/sdram.c
+++ b/litex/soc/software/bios/sdram.c
@@ -731,6 +731,7 @@ int sdrlevel(void)
        int delay[DFII_PIX_DATA_SIZE/2];
        int high_skew[DFII_PIX_DATA_SIZE/2];
        int i, j;
+       int bitslip;
 
        for(i=0; i<DFII_PIX_DATA_SIZE/2; i++) {
                ddrphy_dly_sel_write(1<<i);
@@ -748,20 +749,29 @@ int sdrlevel(void)
        if(!write_level(delay, high_skew))
                return 0;
 #endif
-       /* check for optimal read leveling window */
-       for(i=0; i<ERR_DDRPHY_BITSLIP; i++) {
+       /* check possible read windows (based on bitslip) */
+       for(bitslip=0; bitslip<ERR_DDRPHY_BITSLIP; bitslip++) {
                /* scan */
                if (read_level_scan(1))
                        break;
-               if (i == ERR_DDRPHY_BITSLIP-1)
+               if (bitslip == ERR_DDRPHY_BITSLIP-1)
                        return 0;
                /* increment bitslip */
-               for(j=0; j<DFII_PIX_DATA_SIZE/2; j++)
-                       read_bitslip_inc(j);
+               for(i=0; i<DFII_PIX_DATA_SIZE/2; i++)
+                       read_bitslip_inc(i);
+       }
+
+       /* select read window (bitslip)*/
+       printf("Read bitslip: %d\n", bitslip);
+       for(i=0; i<DFII_PIX_DATA_SIZE/2; i++) {
+               ddrphy_dly_sel_write(1<<i);
+               ddrphy_rdly_dq_bitslip_rst_write(1);
+               for (j=0; j<bitslip; j++)
+                       read_bitslip_inc(i);
        }
-       /* show bitslip and scan */
-       printf("Read bitslip: %d\n", i);
-    read_level_scan(0);
+
+       /* scan selected read window */
+       read_level_scan(0);
        read_level();
 
        return 1;