Author: stepan Date: Wed Mar 17 03:15:07 2010 New Revision: 5238 URL: https://tracker.coreboot.org/trac/coreboot/changeset/5238
Log:
From Keith Hui:
This patch implements a full SDRAM buffer strength programming algorithm in set_dram_buffer_strength(), checked against my P2B-LS factory BIOS. With this in place, I now have 133MHz (!) stability with three 256MB PC133 modules, and can boot Fedora 11 all the way to the init daemon (actually upstart, but that's another story). Not to login prompt yet. We'll find out why later.
This again assumes a 4-DIMM board because that's all I have. I need someone with a 3-DIMM board to test it.
As a bonus, there's a big comment block within that illustrates the algorithm. :-)
Signed-off-by: Keith Hui buurin@gmail.com Acked-by: Stefan Reinauer stepan@coresystems.de
Modified: trunk/src/northbridge/intel/i440bx/raminit.c
Modified: trunk/src/northbridge/intel/i440bx/raminit.c ============================================================================== --- trunk/src/northbridge/intel/i440bx/raminit.c Wed Mar 17 03:09:12 2010 (r5237) +++ trunk/src/northbridge/intel/i440bx/raminit.c Wed Mar 17 03:15:07 2010 (r5238) @@ -431,15 +431,156 @@
static void set_dram_buffer_strength(void) { - /* TODO: This needs to be set according to the DRAM tech - * (x8, x16, or x32). Argh, Intel provides no docs on this! - * Currently, it needs to be pulled from the output of - * lspci -xxx Rx92 + /* To give some breathing room for romcc, + * mbsc0 doubles as drb + * mbsc1 doubles as drb1 + * mbfs0 doubles as i and reg + */ + uint8_t mbsc0,mbsc1,mbsc3,mbsc4,mbfs0,mbfs2,fsb; + + /* Tally how many rows between rows 0-3 and rows 4-7 are populated. + * This determines how to program MBFS and MBSC. + */ + uint8_t dimm03 = 0; + uint8_t dimm47 = 0; + + mbsc0 = 0; + for (mbfs0 = DRB0; mbfs0 <= DRB7; mbfs0++) { + mbsc1 = pci_read_config8(NB, mbfs0); + if (mbsc0 != mbsc1) { + if (mbfs0 <= DRB3) { + dimm03++; + } else { + dimm47++; + } + mbsc0 = mbsc1; + } + } + + /* Algorithm bitmap for programming MBSC[39:0] and MBFS[23:0] + * + * 440BX datasheet says buffer frequency is independent from bus frequency + * and mismatch both ways are possible. This is how it is programmed + * in ASUS P2B-LS. + * + * There are four main conditions to check when programming DRAM buffer + * frequency and strength: + * + * a: >2 rows populated across DIMM0,1 + * b: >2 rows populated across DIMM2,3 + * c: >4 rows populated across all DIMM slots + * and either one of: + * 1: NBXCFG[13] strapped as 100MHz, or + * 6: NBXCFG[13] strapped as 66MHz + * + * CKE0/FENA ----------------------------------------------------------+ + * CKE1/GCKE -------------------[ MBFS ]------------------------+| + * DQMA/CASA[764320]# ----------[ 0 = 66MHz ]-----------------------+|| + * DQMB1/CASB1# ----------------[ 1 = 100MHz ]----------------------+||| + * DQMB5/CASB5# ---------------------------------------------------+|||| + * DQMA1/CASA1# --------------------------------------------------+||||| + * DQMA5/CASA5# -------------------------------------------------+|||||| + * CSA0-5#,CSB0-5# ----------------------------------------++++++||||||| + * CSA6#/CKE2# -------------------------------------------+||||||||||||| + * CSB6#/CKE4# ------------------------------------------+|||||||||||||| + * CSA7#/CKE3# -----------------------------------------+||||||||||||||| + * CSB7#/CKE5# ----------------------------------------+|||||||||||||||| + * MECC[7:0] #2/#1 (100MHz) -------------------------++||||||||||||||||| + * MD[63:0] #2/#1 (100MHz) ------------------------++||||||||||||||||||| + * MAB[12:11,9:0]#,MAB[13,10],WEB#,SRASB#,SCASB# -+||||||||||||||||||||| + * MAA[13:0],WEA#,SRASA#,SCASA# -----------------+|||||||||||||||||||||| + * Reserved ------------------------------------+||||||||||||||||||||||| + * |||||||||||||||||||||||| + * 3 32 21 10 0 * 2 21 10 0 + * 9876543210987654321098765432109876543210 * 321098765432109876543210 + * a 10------------------------1010---------- * -1---------------11----- a + *!a 11------------------------1111---------- * -0---------------00----- !a + * b --10--------------------------1010------ * --1----------------11--- b + *!b --11--------------------------1111------ * --0----------------00--- !b + * c ----------------------------------1100-- * ----------------------1- c + *!c ----------------------------------1011-- * ----------------------0- !c + * 1 ----1010101000000000000000------------00 * ---11111111111111----1-0 1 + * 6 ----000000000000000000000010101010----00 * ---1111111111111100000-0 6 + * | | | | | | | | | | ||||||| | | | | | | + * | | | | | | | | | | ||||||| | | | | | +- CKE0/FENA + * | | | | | | | | | | ||||||| | | | | +--- CKE1/GCKE + * | | | | | | | | | | ||||||| | | | +----- DQMA/CASA[764320]# + * | | | | | | | | | | ||||||| | | +------- DQMB1/CASB1# + * | | | | | | | | | | ||||||| | +--------- DQMB5/CASB5# + * | | | | | | | | | | ||||||| +----------- DQMA1/CASA1# + * | | | | | | | | | | ||||||+------------- DQMA5/CASA5# + * | | | | | | | | | | ++++++-------------- CSA0-5#,CSB0-5# [ 0=1x;1=2x ] + * | | | | | | | | | +--------------------- CSA6#/CKE2# + * | | | | | | | | +---[ MBSC ]------ CSB6#/CKE4# + * | | | | | | | +-----[ 00 = 1x ]------ CSA7#/CKE3# + * | | | | | | +-------[ 01 invalid ]------ CSB7#/CKE5# + * | | | | | +---------[ 10 = 2x ]------ MECC[7:0] #1 (2x) + * | | | | +-----------[ 11 = 3x ]------ MECC[7:0] #2 (2x) + * | | | +--------------------------------- MD[63:0] #1 (2x) + * | | +----------------------------------- MD[63:0] #2 (2x) + * | +------------------------------------- MAB[12:11,9:0]#,MAB[13,10],WEB#,SRASB#,SCASB# + * +--------------------------------------- MAA[13:0],WEA#,SRASA#,SCASA# + * MBSC[47:40] and MBFS[23] are reserved. * - * Relevant registers: MBSC, MBFS, BUFFC. + * This algorithm is checked against P2B-LS factory BIOS. It has 4 DIMM slots. + * Therefore it assumes a board with 4 slots, and will need testing + * on boards with 3 DIMM slots. */ + + mbsc0 = 0x80; + mbsc1 = 0x2a; + mbfs2 = 0x1f; + if (pci_read_config8(NB, NBXCFG + 1) & 0x30) { + fsb = 66; + mbsc3 = 0x00; + mbsc4 = 0x00; + mbfs0 = 0x80; + } else { + fsb = 100; + mbsc3 = 0xa0; + mbsc4 = 0x0a; + mbfs0 = 0x84; + } + + if (dimm03 > 2) { + mbsc4 = mbsc4 | 0x80; + mbsc1 = mbsc1 | 0x28; + mbfs2 = mbfs2 | 0x40; + mbfs0 = mbfs0 | 0x60; + } else { + mbsc4 = mbsc4 | 0xc0; + if (fsb == 100) { + mbsc1 = mbsc1 | 0x3c; + } + } + if (dimm47 > 2) { + mbsc4 = mbsc4 | 0x20; + mbsc1 = mbsc1 | 0x02; + mbsc0 = mbsc0 | 0x80; + mbfs2 = mbfs2 | 0x20; + mbfs0 = mbfs0 | 0x18; + } else { + mbsc4 = mbsc4 | 0x30; + if (fsb == 100) { + mbsc1 = mbsc1 | 0x03; + mbsc0 = mbsc0 | 0xc0; + } + } + if ((dimm03 + dimm47) > 4) { + mbsc0 = mbsc0 | 0x30; + mbfs0 = mbfs0 | 0x02; + } else { + mbsc0 = mbsc0 | 0x2c; + }
- pci_write_config8(NB, MBSC, 0x03); + pci_write_config8(NB, MBSC + 0, mbsc0); + pci_write_config8(NB, MBSC + 1, mbsc1); + pci_write_config8(NB, MBSC + 2, 0x00); + pci_write_config8(NB, MBSC + 3, mbsc3); + pci_write_config8(NB, MBSC + 4, mbsc4); + pci_write_config8(NB, MBFS + 0, mbfs0); + pci_write_config8(NB, MBFS + 1, 0xff); + pci_write_config8(NB, MBFS + 2, mbfs2); }
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