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modules: use the DDR4-2133 tRRD limit on KVR21SE15S84. - #473
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This x8 DDR4-2133 module used tRRD=(4, 4.9), the DDR4-2400 value: tRRD_L is 5.3ns at DDR4-2133 with 1KB pages (Micron 8Gb DDR4 datasheet, Table 161). Set it on the speed grade, with the per speed grade tRRD from #470. The phase margin was covering the difference: among the clocks compared, the controller's tRRD only changes at 50 MHz sys_clk (1 to 2). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Refs #185.
KVR21SE15S84is an x8 DDR4-2133 module and usedtRRD=(4, 4.9), the DDR4-2400 value. tRRD_L is 5.3 ns at DDR4-2133 with 1KB pages (Micron 8Gb DDR4 datasheet, Table 161). It is set on the2133speed grade, using the per speed gradetRRDfrom #470.This is a data correction: the phase margin was covering the difference. Across all modules and 10 clocks from 25 to 400 MHz, the only timing that changes is this module's tRRD at 50 MHz sys_clk (1 to 2).
The table is from Micron and this is a Kingston module; I did not check which dies it uses.
Tested:
test_modules(new test) andtest_timingpass. No hardware.Written by Claude Code (AI agent), supervised by Florent Kermarrec.
🤖 Generated with Claude Code