Remove the TPS65217 driver from the custom built kernel

[Virendra]

Hi,

I am using Debian 8 (from Robert Nelson) with a custom 3.14.17-bone8 kernel on Beaglebone Black.
I want to remove the TPS65217 driver. Could you let me know how to suppress this driver.

Thanks,
Veera

[Robert Nelson]

So, you have a BeagleBone Black, which utilizes the TPS65217 PMIC, and
you'd like to disable it..

Just leave the board un-powered, you'd get the exact same result..

Regards,

--
Robert Nelson
https://rcn-ee.com/

[Virendra Anthony]

Hi Robert,

Is there a way to remove the TPS65217 driver even with board is powered. Wanted to get the TPS65217 driver removed  to make sure the Beaglebone Black is not battery driven.

Thanks,

Veera

[evilwulfie]

can you explain your reason for doing this?
If you dont plug in a battery you cant use power from a battery

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[Virendra]

Hi Wulf,

I am using the custom built kernel image in my own board where the TPS65217 driver is not required as it is not battery driven.

The BBB supports an option to battery backup. It also supports going to sleep mode, and wake-on events to wake up the CPU based on the RTC, 
The TPS65217 supports power saving by lowering the core voltage. I don't need this, as it allows some hardware simplification and flexibility if I don't use this features. Ignoring the TPS65217 will allow me to change the hardware independent of the software.

The way to disabling the TPS65217 may be in the void am33xx_spl_board_init(void) routine that is in the board.c file.  But I am not sure how to do it. Could I get know how to do it.

If I could get the image loaded in BBB with TPS65217 driver removed then it should work for my custom board.

Thanks,
Rafi

[Virendra]

Hi Robert,

The following two lines are enabled in the KERNEL/.config file by default

CONFIG_REGULATOR_TPS65217=y
CONFIG_MFD_TPS65217=y

Is it possible to disable from menuconfig so that both the above items are not included in the built image. Hope disabling the above two line will not include the TPS65217 driver. Could you let me know how to disable it from menuconfig.


Will there be any issues if the above 2 line items are disabled?

Thanks,
Veera

[evilwulfie]

How are you doing the power on cycling of the cpu ?
The CPU and the 65217 work well together to prevent the CPU from going poof !

[Virendra]

I am doing a power on cycling of the CPU by connecting the mini-USB

[Robert Nelson]

On Feb 27, 2016 7:27 AM, "Virendra" <ardn...@gmail.com> wrote:
>
> I am doing a power on cycling of the CPU by connecting the mini-USB

The CPU, am335x doesn't not run off USB/5 volts.. It needs the tps65217, to provide multiple voltages to operate...

If you disable the tps65217, this board will not boot..

Regards,

[John Syne]

In addition to what Robert just explained, the TPS65217 also controls the sequence of turning on these various voltages. If you do not adhere to the AM3358 CPU datasheet voltage turn on and turn off sequence, you will damage the CPU. I cannot imagine there will be a way to use the BBB without the TPS65217. 

Regards,

John

[Virendra]

Hi Robert,

I am planning to use this custom built image in another board which is not Beagle boar. That board doesn't require voltage from battery.
Is there an option to disable the tps65217 so that i can try the image in my own board and not in Beagleboard.

Also there seems to be a link where they are mentioning about removing the tps65217.dtsi

https://lkml.org/lkml/2015/10/27/33

Thanks,
Veera

[Robert Nelson]

On Sun, Feb 28, 2016 at 8:25 PM, Virendra <ardn...@gmail.com> wrote:
> Hi Robert,
>
> I am planning to use this custom built image in another board which is not
> Beagle boar. That board doesn't require voltage from battery.
> Is there an option to disable the tps65217 so that i can try the image in my
> own board and not in Beagleboard.

Your first line: "kernel on Beaglebone Black."

Look at the board schematic

https://github.com/CircuitCo/BeagleBone-Black/blob/master/BBB_SCH.pdf

See Page 2... that's the tps65217 providing "ALL" the power rails for
the am335x.

Disabling the tps65217 on the "BeagleBone Black" is about the most
"stupid" thing one can do..

Now all of sudden: "another board which is not Beagle boar."

Well you should have led with that thought..

So what board are we talking about? Is there a schematic available?

> Also there seems to be a link where they are mentioning about removing the
> tps65217.dtsi
>
> https://lkml.org/lkml/2015/10/27/33

That's a completely different topic, that was about "removing" the
tps65217.dtsi "FILE" and re-factoring the code..

anyhow that got yanked:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/arm/boot/dts?id=e327b3f564031a8d0090a6b3e3562a8b59bafe0e

as someone had forgotten to test the beaglebone white..

[John Syne]

Like Robert, I’m having a difficult time understanding what it is you are trying to do. If you are using the BBB, you cannot run the board without the TPS65217 enabled because it is this chip that is supplying all the voltage rails needed by the AM3358. If you have a different board with another voltage regulator, then you must modify the kernel to enable another voltage regulator. If the regulator does not exist within the Linux kernel, then you will have to write your own, using driver/regulator/tps65217.c as your template. This is not a trivial task, and if you are asking this question, then you don’t have the skills necessary to build your own. Best to hire someone with the expertise required to complete this task.

Regards,
John

[Angelo Fares Menhem]

Hey Guys,

The problem of using a LiIon battery to allow BeageBone boards to orderly shutdown is object of several posts here.

In my particular case I just want to use the battery power to allow shutdown and disconnect the battery from the power path at the end of power down sequence to work around the problem of VSYS being kept with 4,1 V causing VDD_3V3A to set to around 0,8V.

As I don't intend to run on battery nor on USB, I came up with this solution and I would like to have your thoughts in why it didn't work ....

The whole idea is to connect the battery in the USB input of the PMIC (instead of BAT terminal) allowing battery power to be connected/disconnected using power path control bit D4 in the Power Path Control Register (PPATH). With this I can change the shutdown routine of the OS to disconnect the battery power from VSYS  just at the end of the power off cycle, before issuing the POWER_EN Signal.

As the battery still needs to be charged, my idea is to connect BAT SENSE to the battery (+) and connect BAT to BAT SENSE via a low Vf diode in order to prevent the battery from supplying the original power path. It should work because the charging cycle tests the battery presence sending a small current to it and sensing the voltage (via BAT SENSE I suppose). Naturally TS is supposed to be connect do a 10K resistor to ground.

However, it didn't work! PMIC just didn't turn on when AC input is connect to a suitable  5V power supply.

Below is the circuit:

Does someone can explain why not?

Best regards