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soc/software/bios/sdram: improve write_level robustness

This commit is contained in:
Florent Kermarrec 2019-02-25 14:38:24 +01:00
parent 36772b75f6
commit 2fd6d0e7e1
1 changed files with 18 additions and 8 deletions
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22
litex/soc/software/bios/sdram.c
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@ -277,13 +277,14 @@ int write_level(void)
unsigned char taps_scan[ERR_DDRPHY_DELAY]; unsigned char taps_scan[ERR_DDRPHY_DELAY];
int one_window_active; int one_window_active;
int one_window_start; int one_window_start, one_window_best_start;
int one_window_count, one_window_best_count;
int delays[NBMODULES]; int delays[NBMODULES];
int ok; int ok;
err_ddrphy_wdly = (ERR_DDRPHY_DELAY*14)/16 - ddrphy_half_sys8x_taps_read(); err_ddrphy_wdly = ERR_DDRPHY_DELAY - ddrphy_half_sys8x_taps_read();
printf("Write leveling:\n"); printf("Write leveling:\n");
@ -296,7 +297,7 @@ int write_level(void)
/* rst delay */ /* rst delay */
write_delay_rst(i); write_delay_rst(i);
/* scan taps */ /* scan write delay taps */
for(j=0;j<err_ddrphy_wdly;j++) { for(j=0;j<err_ddrphy_wdly;j++) {
int zero_count = 0; int zero_count = 0;
int one_count = 0; int one_count = 0;
@ -324,14 +325,23 @@ int write_level(void)
} }
printf("|"); printf("|");
/* select last 0/1 transition */ /* find longer 1 window and set delay at the 0/1 transition */
one_window_active = 0; one_window_active = 0;
one_window_start = 0; one_window_start = 0;
one_window_count = 0;
one_window_best_start = 0;
one_window_best_count = 0;
delays[i] = -1; delays[i] = -1;
for(j=0;j<err_ddrphy_wdly;j++) { for(j=0;j<err_ddrphy_wdly;j++) {
if (one_window_active) { if (one_window_active) {
if (taps_scan[j] == 0) if ((taps_scan[j] == 0) | (j == err_ddrphy_wdly - 1)) {
one_window_active = 0; one_window_active = 0;
one_window_count = j - one_window_start;
if (one_window_count > one_window_best_count) {
one_window_best_start = one_window_start;
one_window_best_count = one_window_count;
}
}
} else { } else {
if (taps_scan[j]) { if (taps_scan[j]) {
one_window_active = 1; one_window_active = 1;
@ -339,7 +349,7 @@ int write_level(void)
} }
} }
} }
delays[i] = one_window_start; delays[i] = one_window_best_start;
/* configure write delay */ /* configure write delay */
write_delay_rst(i); write_delay_rst(i);