[U-Boot-Users] Question about spd_sdram function
arcadyg at gmail.com
Tue Dec 18 15:00:37 CET 2007
I'm working with MPC8548 based board and use U-Boot 1.2.0.
I use hard-coded values for memory controller,
but in nearest future I want to use SPD based initialization,
so there is a question related to SPD code.
Looking at spd_sdram function at next code:
/---- start of code ----/
* Convert trfc_clk to DDR controller fields. DDR I should
* fit in the REFREC field (16-19) of TIMING_CFG_1, but the
* 8548 controller has an extended REFREC field of three bits.
* The controller automatically adds 8 clocks to this value,
* so preadjust it down 8 first before splitting it up.
trfc_low = (trfc_clk - 8) & 0xf;
trfc_high = ((trfc_clk - 8) >> 4) & 0x3;
/---- end of code ----/
there is inconsistency in code and comment - the value of REFREC extended
stored at trfc_high variable and contains only two bits of calculation,
but comments above and spec of MPC8548 say that the EXT_REFREC field is 3
(i.e. should be trfc_high = ((trfc_clk - 8) >> 4) & 0x7; ).
Is it a bug ?
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