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soc/software/liblitedram: make leveling scores more robust by counting number of bitslips

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This commit is contained in:
Jędrzej Boczar 2021-05-17 14:53:04 +02:00
parent 50805797c6
commit 93f357d853
1 changed files with 68 additions and 28 deletions
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96
litex/soc/software/liblitedram/sdram.c
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@ -28,6 +28,7 @@
//#define SDRAM_TEST_DISABLE //#define SDRAM_TEST_DISABLE
//#define SDRAM_WRITE_LEVELING_CMD_DELAY_DEBUG //#define SDRAM_WRITE_LEVELING_CMD_DELAY_DEBUG
//#define SDRAM_WRITE_LATENCY_CALIBRATION_DEBUG //#define SDRAM_WRITE_LATENCY_CALIBRATION_DEBUG
//#define SDRAM_LEVELING_SCAN_DISPLAY_HEX_DIV 10
#ifdef CSR_SDRAM_BASE #ifdef CSR_SDRAM_BASE
@ -272,8 +273,37 @@ static void sdram_precharge_test_row(void) {
cdelay(15); cdelay(15);
} }
static int sdram_write_read_check_test_pattern(int module, unsigned int seed) { // Count number of bits in a 32-bit word, faster version than a while loop
// see: https://www.johndcook.com/blog/2020/02/21/popcount/
static unsigned int popcount(unsigned int x) {
x -= ((x >> 1) & 0x55555555);
x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
x = (x + (x >> 4)) & 0x0F0F0F0F;
x += (x >> 8);
x += (x >> 16);
return x & 0x0000003F;
}
static void print_scan_errors(unsigned int errors) {
#ifdef SDRAM_LEVELING_SCAN_DISPLAY_HEX_DIV
// Display '.' for no errors, errors/div in hex if it is a single char, else show 'X'
errors = errors / SDRAM_LEVELING_SCAN_DISPLAY_HEX_DIV;
if (errors == 0)
printf(".");
else if (errors > 0xf)
printf("X");
else
printf("%x", errors);
#else
printf("%d", errors == 0);
#endif
}
#define READ_CHECK_TEST_PATTERN_MAX_ERRORS (SDRAM_PHY_PHASES*2*32)
static unsigned int sdram_write_read_check_test_pattern(int module, unsigned int seed) {
int p, i; int p, i;
unsigned int errors;
unsigned int prv; unsigned int prv;
unsigned char tst[DFII_PIX_DATA_BYTES]; unsigned char tst[DFII_PIX_DATA_BYTES];
unsigned char prs[SDRAM_PHY_PHASES][DFII_PIX_DATA_BYTES]; unsigned char prs[SDRAM_PHY_PHASES][DFII_PIX_DATA_BYTES];
@ -311,13 +341,13 @@ static int sdram_write_read_check_test_pattern(int module, unsigned int seed) {
/* Precharge */ /* Precharge */
sdram_precharge_test_row(); sdram_precharge_test_row();
errors = 0;
for(p=0;p<SDRAM_PHY_PHASES;p++) { for(p=0;p<SDRAM_PHY_PHASES;p++) {
/* Read back test pattern */ /* Read back test pattern */
csr_rd_buf_uint8(sdram_dfii_pix_rddata_addr(p), tst, DFII_PIX_DATA_BYTES); csr_rd_buf_uint8(sdram_dfii_pix_rddata_addr(p), tst, DFII_PIX_DATA_BYTES);
/* Verify bytes matching current 'module' */ /* Verify bytes matching current 'module' */
if (prs[p][ SDRAM_PHY_MODULES-1-module] != tst[ SDRAM_PHY_MODULES-1-module] || errors += popcount(prs[p][ SDRAM_PHY_MODULES-1-module] ^ tst[ SDRAM_PHY_MODULES-1-module]);
prs[p][2*SDRAM_PHY_MODULES-1-module] != tst[2*SDRAM_PHY_MODULES-1-module]) errors += popcount(prs[p][2*SDRAM_PHY_MODULES-1-module] ^ tst[2*SDRAM_PHY_MODULES-1-module]);
return 0;
} }
#ifdef SDRAM_PHY_ECP5DDRPHY #ifdef SDRAM_PHY_ECP5DDRPHY
@ -325,7 +355,7 @@ static int sdram_write_read_check_test_pattern(int module, unsigned int seed) {
return 0; return 0;
#endif #endif
return 1; return errors;
} }
static void sdram_leveling_center_module( static void sdram_leveling_center_module(
@ -334,6 +364,7 @@ static void sdram_leveling_center_module(
int i; int i;
int show; int show;
int working; int working;
unsigned int errors;
int delay, delay_mid, delay_range; int delay, delay_mid, delay_range;
int delay_min = -1, delay_max = -1; int delay_min = -1, delay_max = -1;
@ -344,14 +375,15 @@ static void sdram_leveling_center_module(
delay = 0; delay = 0;
rst_delay(module); rst_delay(module);
while(1) { while(1) {
working = sdram_write_read_check_test_pattern(module, 42); errors = sdram_write_read_check_test_pattern(module, 42);
working &= sdram_write_read_check_test_pattern(module, 84); errors += sdram_write_read_check_test_pattern(module, 84);
working = errors == 0;
show = show_long; show = show_long;
#if SDRAM_PHY_DELAYS > 32 #if SDRAM_PHY_DELAYS > 32
show = show && (delay%16 == 0); show = show && (delay%16 == 0);
#endif #endif
if (show) if (show)
printf(working ? "1" : "0"); print_scan_errors(errors);
if(working && delay_min < 0) { if(working && delay_min < 0) {
delay_min = delay; delay_min = delay;
break; break;
@ -375,14 +407,15 @@ static void sdram_leveling_center_module(
/* Find largest working delay */ /* Find largest working delay */
while(1) { while(1) {
working = sdram_write_read_check_test_pattern(module, 42); errors = sdram_write_read_check_test_pattern(module, 42);
working &= sdram_write_read_check_test_pattern(module, 84); errors += sdram_write_read_check_test_pattern(module, 84);
working = errors == 0;
show = show_long; show = show_long;
#if SDRAM_PHY_DELAYS > 32 #if SDRAM_PHY_DELAYS > 32
show = show && (delay%16 == 0); show = show && (delay%16 == 0);
#endif #endif
if (show) if (show)
printf(working ? "1" : "0"); print_scan_errors(errors);
if(!working && delay_max < 0) { if(!working && delay_max < 0) {
delay_max = delay; delay_max = delay;
} }
@ -874,15 +907,17 @@ static void sdram_read_leveling_inc_bitslip(char m)
ddrphy_dly_sel_write(0); ddrphy_dly_sel_write(0);
} }
static int sdram_read_leveling_scan_module(int module, int bitslip, int show) static unsigned int sdram_read_leveling_scan_module(int module, int bitslip, int show)
{ {
const unsigned int max_errors = 2*READ_CHECK_TEST_PATTERN_MAX_ERRORS;
int i; int i;
int score; unsigned int score;
unsigned int errors;
/* Check test pattern for each delay value */ /* Check test pattern for each delay value */
score = 0; score = 0;
if (show) if (show)
printf(" m%d, b%d: |", module, bitslip); printf(" m%d, b%02d: |", module, bitslip);
sdram_read_leveling_rst_delay(module); sdram_read_leveling_rst_delay(module);
for(i=0;i<SDRAM_PHY_DELAYS;i++) { for(i=0;i<SDRAM_PHY_DELAYS;i++) {
int working; int working;
@ -890,11 +925,14 @@ static int sdram_read_leveling_scan_module(int module, int bitslip, int show)
#if SDRAM_PHY_DELAYS > 32 #if SDRAM_PHY_DELAYS > 32
_show = (i%16 == 0) & show; _show = (i%16 == 0) & show;
#endif #endif
working = sdram_write_read_check_test_pattern(module, 42); errors = sdram_write_read_check_test_pattern(module, 42);
working &= sdram_write_read_check_test_pattern(module, 84); errors += sdram_write_read_check_test_pattern(module, 84);
if (_show) working = errors == 0;
printf("%d", working); /* When any scan is working then the final score will always be higher then if no scan was working */
score += working; score += (working * max_errors*SDRAM_PHY_DELAYS) + (max_errors - errors);
if (_show) {
print_scan_errors(errors);
}
sdram_read_leveling_inc_delay(module); sdram_read_leveling_inc_delay(module);
} }
if (show) if (show)
@ -915,8 +953,8 @@ void sdram_read_leveling(void)
{ {
int module; int module;
int bitslip; int bitslip;
int score; unsigned int score;
int best_score; unsigned int best_score;
int best_bitslip; int best_bitslip;
for(module=0; module<SDRAM_PHY_MODULES; module++) { for(module=0; module<SDRAM_PHY_MODULES; module++) {
@ -964,8 +1002,9 @@ static void sdram_write_latency_calibration(void) {
int i; int i;
int module; int module;
int bitslip; int bitslip;
int score; unsigned int score;
int best_score; unsigned int subscore;
unsigned int best_score;
int best_bitslip; int best_bitslip;
for(module=0; module<SDRAM_PHY_MODULES; module++) { for(module=0; module<SDRAM_PHY_MODULES; module++) {
@ -991,11 +1030,12 @@ static void sdram_write_latency_calibration(void) {
for(i=0; i<SDRAM_PHY_BITSLIPS; i++) { for(i=0; i<SDRAM_PHY_BITSLIPS; i++) {
/* Compute score */ /* Compute score */
#ifdef SDRAM_WRITE_LATENCY_CALIBRATION_DEBUG #ifdef SDRAM_WRITE_LATENCY_CALIBRATION_DEBUG
score += sdram_read_leveling_scan_module(module, i, 1); subscore = sdram_read_leveling_scan_module(module, i, 1);
printf("\n"); printf("\n");
#else #else
score += sdram_read_leveling_scan_module(module, i, 0); subscore = sdram_read_leveling_scan_module(module, i, 0);
#endif #endif
score = subscore > score ? subscore : score;
/* Increment bitslip */ /* Increment bitslip */
sdram_read_leveling_inc_bitslip(module); sdram_read_leveling_inc_bitslip(module);
} }
@ -1073,10 +1113,10 @@ static void sdram_write_dq_dqs_training_inc_delay(int module) {
static void sdram_read_leveling_best_bitslip(int module) static void sdram_read_leveling_best_bitslip(int module)
{ {
int score; unsigned int score;
int bitslip; int bitslip;
int best_bitslip = 0; int best_bitslip = 0;
int best_score = 0; unsigned int best_score = 0;
sdram_read_leveling_rst_bitslip(module); sdram_read_leveling_rst_bitslip(module);
for(bitslip=0; bitslip<SDRAM_PHY_BITSLIPS; bitslip++) { for(bitslip=0; bitslip<SDRAM_PHY_BITSLIPS; bitslip++) {