[coreboot-gerrit] Change in coreboot[master]: nb/intel/x4x/raminit: Rework receive enable calibration
Arthur Heymans (Code Review)
gerrit at coreboot.org
Thu Jun 1 22:01:55 CEST 2017
Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/18692 )
Change subject: nb/intel/x4x/raminit: Rework receive enable calibration
......................................................................
Patch Set 21:
(3 comments)
https://review.coreboot.org/#/c/18692/21/src/northbridge/intel/x4x/rcven.c
File src/northbridge/intel/x4x/rcven.c:
PS21, Line 40: #define SAMPLE_COUNT 3
does not seem to improve things.
PS21, Line 174: if (sampledqs(addr, lane, channel, DQS_HIGH)) {
: printk(BIOS_WARNING, "DQS already HIGH... DQS probe is incosistent!\n"
: "Continuing, but be cautious of possible instabilities.\n");
Is still being hit very consistently, so I think there is some hysteresis in this dram controller. I'll just documented it and maybe adapt printed message.
PS21, Line 218: /* Some settings are very noisy. Check the next tap */
: /* if the result of the probe is consistent. */
: if (sampledqs(addr, lane, channel, DQS_HIGH)) {
: increase_tap(timing);
: program_timing(timing, channel, lane);
: if (sampledqs(addr, lane, channel, DQS_HIGH)) {
: decrease_tap(timing);
: program_timing(timing, channel, lane);
: break;
: } else {
: decrease_tap(timing);
: }
: }
Does not seem to improve things since problems don't seem to be caused that much by noise but by hysteresis.
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Gerrit-MessageType: comment
Gerrit-Change-Id: I0c970455e609d3ce96a262cbf110336a2079da4d
Gerrit-PatchSet: 21
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