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arm: mx6: Clamp MMDC and DDR3 clocks for timing calculations 

This is proposal for clamping the MMDC/DDR3 clocks to the maximum supported
frequencies as per imx6 SOC models, and for dynamically calculating valid
clock value based on mem_speed.

Currently the code uses impossible values for mem_speed (1333, 1600 MT/s) for
calculating the DDR timings, and uses fixed clock (528 or 400 MHz) which
doesn't take into account DDR3 memory limitations.

Signed-off-by: Nikolay Dimitrov <picmaster@mail.bg>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tim Harvey <tharvey@gateworks.com>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
This commit is contained in:
Nikolay Dimitrov 2015-04-22 18:37:31 +03:00 committed by Stefano Babic
parent 19f74d885f
commit 8a2bd215a2
1 changed files with 23 additions and 7 deletions
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30
arch/arm/cpu/armv7/mx6/ddr.c
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@ -265,24 +265,40 @@ void mx6_dram_cfg(const struct mx6_ddr_sysinfo *sysinfo,
u16 tdllk = 0x1ff; /* DLL locking time: 512 cycles (JEDEC DDR3) */
u8 coladdr;
int clkper; /* clock period in picoseconds */
int clock; /* clock freq in mHz */
int clock; /* clock freq in MHz */
int cs;
u16 mem_speed = ddr3_cfg->mem_speed;
mmdc0 = (struct mmdc_p_regs *)MMDC_P0_BASE_ADDR;
#ifndef CONFIG_MX6SX
mmdc1 = (struct mmdc_p_regs *)MMDC_P1_BASE_ADDR;
#endif
/* MX6D/MX6Q: 1066 MHz memory clock, clkper = 1.894ns = 1894ps */
/* Limit mem_speed for MX6D/MX6Q */
if (is_cpu_type(MXC_CPU_MX6Q) || is_cpu_type(MXC_CPU_MX6D)) {
clock = 528;
if (mem_speed > 1066)
mem_speed = 1066; /* 1066 MT/s */
tcwl = 4;
}
/* MX6S/MX6DL: 800 MHz memory clock, clkper = 2.5ns = 2500ps */
/* Limit mem_speed for MX6S/MX6DL */
else {
clock = 400;
if (mem_speed > 800)
mem_speed = 800; /* 800 MT/s */
tcwl = 3;
}
clock = mem_speed / 2;
/*
* Data rate of 1066 MT/s requires 533 MHz DDR3 clock, but MX6D/Q supports
* up to 528 MHz, so reduce the clock to fit chip specs
*/
if (is_cpu_type(MXC_CPU_MX6Q) || is_cpu_type(MXC_CPU_MX6D)) {
if (clock > 528)
clock = 528; /* 528 MHz */
}
clkper = (1000 * 1000) / clock; /* pico seconds */
todtlon = tcwl;
taxpd = tcwl;
@ -313,7 +329,7 @@ void mx6_dram_cfg(const struct mx6_ddr_sysinfo *sysinfo,
}
txpr = txs;
switch (ddr3_cfg->mem_speed) {
switch (mem_speed) {
case 800:
txp = DIV_ROUND_UP(max(3 * clkper, 7500), clkper) - 1;
tcke = DIV_ROUND_UP(max(3 * clkper, 7500), clkper) - 1;
@ -382,7 +398,7 @@ void mx6_dram_cfg(const struct mx6_ddr_sysinfo *sysinfo,
debug("density:%d Gb (%d Gb per chip)\n",
sysinfo->cs_density, ddr3_cfg->density);
debug("clock: %dMHz (%d ps)\n", clock, clkper);
debug("memspd:%d\n", ddr3_cfg->mem_speed);
debug("memspd:%d\n", mem_speed);
debug("tcke=%d\n", tcke);
debug("tcksrx=%d\n", tcksrx);
debug("tcksre=%d\n", tcksre);