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bios/sdram: improve bitslip selection when window can't be optimal (not enough taps for a full window)

This commit is contained in:
Florent Kermarrec 2018-07-16 09:42:09 +02:00
parent 7dbd85a842
commit 4f1274e6a6
1 changed files with 5 additions and 1 deletions
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6
litex/soc/software/bios/sdram.c
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@ -377,6 +377,7 @@ static int read_level_scan(int silent)
unsigned char prs[DFII_NPHASES*DFII_PIX_DATA_SIZE];
int p, i, j;
int working;
int working_delays;
int optimal;
if (!silent)
@ -407,6 +408,7 @@ static int read_level_scan(int silent)
sdram_dfii_pird_address_write(0);
sdram_dfii_pird_baddress_write(0);
working = 0;
working_delays = 0;
optimal = 1;
for(i=DFII_PIX_DATA_SIZE/2-1;i>=0;i--) {
if (!silent)
@ -425,6 +427,7 @@ static int read_level_scan(int silent)
working_delay = 0;
}
working |= working_delay;
working_delays += working_delay;
if ((j == 0) || (j == (ERR_DDRPHY_DELAY-1)))
/* to have an optimal scan, first tap and last tap should not be working */
optimal &= (working_delay == 0);
@ -442,7 +445,8 @@ static int read_level_scan(int silent)
command_p0(DFII_COMMAND_RAS|DFII_COMMAND_WE|DFII_COMMAND_CS);
cdelay(15);
return working & optimal;
/* Successful if working and optimal or if number of working delays > 3/4 of the taps */
return (working & optimal) | (working_delays > 3*ERR_DDRPHY_DELAY/4);
}
static void read_level(void)