TPS65217 & Vdd_core 1.125V or 1.2V or 1.1V or .... ?

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Micka

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May 18, 2016, 4:59:04 AM5/18/16
to beagl...@googlegroups.com, Gerald Coley
Hi,


there is those lines :

255                 /* Set DCDC3 (CORE) voltage to 1.125V */
256                 if (tps65217_voltage_update(TPS65217_DEFDCDC3,
257                                             TPS65217_DCDC_VOLT_SEL_1125MV))


In the device tree there is those lines :

dcdc3_reg: regulator@2 {
/* VDD_CORE voltage limits 0.95V - 1.1V with +/-4% tolerance */
regulator-name = "vdd_core";
regulator-min-microvolt = <925000>;
regulator-max-microvolt = <1150000>;
regulator-boot-on;
regulator-always-on;
};

in the starterware from texas + the patch for the bbb I have nothing concerning the DEFDCD3. 

And finally in the BBB_SRM you have those lines :

The VDD_CORE rail can deliver up to 1.2A at 1.1V. This rail is not accessible for use anywhere else on the board and only connects to the processor. This rail is fixed at 1.1V and is not scaled.  

So what is the correct configuration for this output ?


Micka,


John Syne

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May 18, 2016, 4:31:29 PM5/18/16
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I believe this is done in bootloader/src/armv7a/am335x/bl_platform.c

In essence, you have to create a bootable SDCard for Starterware which sets the regulator voltages for you. 

Regards,
John


Micka,



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Micka

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May 19, 2016, 3:47:19 AM5/19/16
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I already looked at that file and in the starterware there is no line that contain DEFDCD3.

What I'm saying, is that nowhere I find the same value for DEFDCD3. Some time it's 1.125V, somehwere else it's .95V-1.1V and in the BB_SRM it is 1.1V .

I'm asking to Gerald, what is the correct value for Vdd_Core ? I think that the correct one is 1.1V. And what is the range ? 0.95V-1.1V ( device tree )

To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/D2B2F1F3-E3ED-43C6-9B24-2D32028E99B4%40gmail.com.

John Syne

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May 19, 2016, 3:01:28 PM5/19/16
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I believe the voltage is adjusted based on CPU frequency. If the CPU governor is set to dynamic, then the voltage will adjust as the CPU frequency changes.

Regards,
John




John Syne

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May 19, 2016, 3:03:45 PM5/19/16
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On May 19, 2016, at 12:46 AM, Micka <micka...@gmail.com> wrote:

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