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4470 emif parameter setting

sam liu1
Intellectual 310 points

Hello,i use 4470 4AI.1.3.

In kernel/android-3.0/arch/arm/mach-omap2/lpddr2_elpida_data.c

i found follow code.

struct lpddr2_device_info lpddr2_elpida_4G_S4_dev = {

.device_timings = {
&lpddr2_elpida_timings_200_mhz,
&lpddr2_elpida_timings_333_mhz,
&lpddr2_elpida_timings_400_mhz,
&lpddr2_elpida_timings_466_mhz,
},
.min_tck = &lpddr2_elpida_min_tck,
.type = LPDDR2_TYPE_S4,
.density = LPDDR2_DENSITY_4Gb,
.io_width = LPDDR2_IO_WIDTH_32,
.emif_ddr_selfrefresh_cycles = 262144,
};

I know 4470 tablet2 in x-loader have config the DDR to 4Gbit/466Mhz.
What the purpose of other 3 frequence(200/333/400) parameter?Use at which function.
thanks.

  • 0
    TI__Expert 4120 points

    Hi Sam,

    As per my understanding, all these four frequencies are defined by the power management framework in accordance with operating points so that depending on the load on DDR, the power management framework would switch the DDR to operate at lower frequencies for optimum power consumption.

    I hope this clarifies your query.

    Thanks & Best Regards,

    Venkat

  • 0 in reply to Venkat Ramana Peddigari
    Intellectual 310 points

    1.those four frequencies  is for  "smart-reflex" ?

    2.How to enable/disable those dynamic DDR  frequence change function.

    thanks 

  • 0 in reply to sam liu1
    TI__Intellectual 815 points

    Hey Sam,

    The four frequencies are not due to Smart-Reflex.  Smart-reflex deals with the MPU, IVA, and CORE voltages.

    When the x-loader sets the frequency to 466MHz, this is just for initialization/bootup.  Once the kernel comes online, it takes over and changes the LPDDR frequency accordingly.  For example, when the system is running at a lighter load, the LPDDR does not need to run at the max frequency, so the power management framework ramps it down to save power, like Venkat said.  It is not recommended to disable the DDR frequency changing as it will have an unnecessary impact on power savings.  

    Regards,

    Alex