diff options
| -rw-r--r-- | src/northbridge/intel/sandybridge/raminit_common.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/src/northbridge/intel/sandybridge/raminit_common.c b/src/northbridge/intel/sandybridge/raminit_common.c index 092e34dd0a..f766867965 100644 --- a/src/northbridge/intel/sandybridge/raminit_common.c +++ b/src/northbridge/intel/sandybridge/raminit_common.c @@ -977,14 +977,24 @@ void program_timings(ramctr_timing *ctrl, int channel) } } FOR_ALL_POPULATED_RANKS { - u32 clk_delay = ctrl->timings[channel][slotrank].pi_coding + cmd_delay; + int clk_delay = ctrl->timings[channel][slotrank].pi_coding + cmd_delay; - if (clk_delay > CCC_MAX_PI) { - printk(BIOS_ERR, "C%dR%d clock delay overflow: %d\n", + /* + * Clock is a differential signal, whereas command and control are not. + * This affects its timing, and it is also why it needs a magic offset. + */ + clk_delay += ctrl->pi_code_offset; + + /* Can never happen with valid values */ + if (clk_delay < 0) { + printk(BIOS_ERR, "C%dR%d clock delay underflow: %d\n", channel, slotrank, clk_delay); - clk_delay = CCC_MAX_PI; + clk_delay = 0; } + /* Clock can safely wrap around because it is a periodic signal */ + clk_delay %= CCC_MAX_PI + 1; + clk_pi_coding |= (clk_delay % QCLK_PI) << (6 * slotrank); clk_logic_dly |= (clk_delay / QCLK_PI) << slotrank; } |