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fsl-ddr: Fix the turnaround timing for TIMING_CFG_4 

Read-to-read/Write-to-write turnaround for same chip select
of DDR3 memory, BL/2+2 cycles is enough for them at BC4 and
OTF case, BL/2 cycles is enough for fixed BL8.
Cutting down the turnaround from BL/2+4 to BL/2+2 or BL/2
will improve the memory performance.

Signed-off-by: Dave Liu <daveliu@freescale.com>
This commit is contained in:
Dave Liu 2010-03-05 12:22:00 +08:00 committed by Kumar Gala
parent ab467c512e
commit ec145e87b8
1 changed files with 17 additions and 9 deletions
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26
cpu/mpc8xxx/ddr/ctrl_regs.c
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@ -1,9 +1,10 @@
/*
* Copyright 2008-2009 Freescale Semiconductor, Inc.
* Copyright 2008-2010 Freescale Semiconductor, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* Version 2 as published by the Free Software Foundation.
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*/
/*
@ -934,7 +935,8 @@ static void set_ddr_init_ext_addr(fsl_ddr_cfg_regs_t *ddr)
}
/* DDR SDRAM Timing Configuration 4 (TIMING_CFG_4) */
static void set_timing_cfg_4(fsl_ddr_cfg_regs_t *ddr)
static void set_timing_cfg_4(fsl_ddr_cfg_regs_t *ddr,
const memctl_options_t *popts)
{
unsigned int rwt = 0; /* Read-to-write turnaround for same CS */
unsigned int wrt = 0; /* Write-to-read turnaround for same CS */
@ -943,9 +945,15 @@ static void set_timing_cfg_4(fsl_ddr_cfg_regs_t *ddr)
unsigned int dll_lock = 0; /* DDR SDRAM DLL Lock Time */
#if defined(CONFIG_FSL_DDR3)
/* We need set BL/2 + 4 for BC4 or OTF */
rrt = 4; /* BL/2 + 4 clocks */
wwt = 4; /* BL/2 + 4 clocks */
if (popts->burst_length == DDR_BL8) {
/* We set BL/2 for fixed BL8 */
rrt = 0; /* BL/2 clocks */
wwt = 0; /* BL/2 clocks */
} else {
/* We need to set BL/2 + 2 to BC4 and OTF */
rrt = 2; /* BL/2 + 2 clocks */
wwt = 2; /* BL/2 + 2 clocks */
}
dll_lock = 1; /* tDLLK = 512 clocks from spec */
#endif
ddr->timing_cfg_4 = (0
@ -1343,7 +1351,7 @@ compute_fsl_memctl_config_regs(const memctl_options_t *popts,
set_ddr_sdram_clk_cntl(ddr, popts);
set_ddr_init_addr(ddr);
set_ddr_init_ext_addr(ddr);
set_timing_cfg_4(ddr);
set_timing_cfg_4(ddr, popts);
set_timing_cfg_5(ddr);
set_ddr_zq_cntl(ddr, zq_en);