How do I test SMARTREFLEX?

Hi Robert,

Could you please provide the details of which board you are using, s/w version details etc.

Thanks

Anilkumar

Hi Anil,

it's a custom board fitted with C6A8168. The voltage levels and GPIOs are identical with evm816x_Schematics_RevE.pdf.

I use EZSDK 5.02.02.60

- Robert

Hi Robert,

If you are changing PMIC (Power management IC) to new one then you have to develop new voltage regulator driver (According to new PMIC) .

AVS is applicable to only "1V AVS voltage domain" and there is no standard test application available for AVS testing.

Things need to be taken care, while checking the AVS operation:

1. Check whether the voltage changes in the hardware if you change voltage from voltage regulator driver.

2. Check whether the voltage is lower than default (1.01V) voltage after AVS operation starts (by default AVS starts operation during AVS init).

3. Check whether the system is stable after voltage changed to new voltage (lower than 1.01V)

Please go through these wikis for details on AVS driver

http://processors.wiki.ti.com/index.php/DM816x_C6A816x_AM386x_AVS_Driver_Guide

http://processors.wiki.ti.com/index.php/DM816x_C6A816x_AM389x_AVS_FAQ

Regards

Anilkumar

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Hi Anil,

the HW is fully compatible with gpio regulator griver, works fine and I don't need to develop a new voltage regulator driver.

1) This works. I set a voltage value in regulator driver and measure same value on AVS.

2) The board starts with 0.920V. When SMARTREFLEX driver is initialized drops to 0.875

3) What tests would you run?

When I run CPU in different scenarious (for example 3D demo, sleep command ...) I don't see any changes on AVS voltage rail.

At what condition the AVS will change? When should I expect to measure the lowest core voltage and when the highest?

From datasheet:

The device contains SmartReflex modules that are required to minimize power consumption on the
voltage domains using external variable-voltage power supplies. Based on the device process,
temperature, and desired performance, the SmartReflex modules advise the host processor to raise or
lower the supply voltage to each domain for minimal power consumption.

The major technique employed by SmartReflex in the device is adaptive voltage scaling (AVS). Based on
the silicon process and temperature, the SmartReflex modules guide software in adjusting the core 1-V
supply voltage within the desired range. This technique is called adaptive voltage scaling (AVS). AVS
occurs continuously and in real time, helping to minimize power consumption in response to changing
operating conditions.

Thank you,

- Robert

Robert,

The AVS delivered in SDK 5.02.01.59 is not dynamic, it takes a single sample of HVT (High Voltage Threshold) and SVT (Standard Voltage Threshold) during Linux startup and performs a one time adjustment.

TI does not offer any technical details regarding HVT and SVT, but there is a patent application which details what these values represent - find it here: http://www.freepatentsonline.com/y2008/0120065.html

AVS starts up in ti8168_evm_init(). Find this function in: /ti-ezsdk_dm816x-evm_5_02_01_59/board-support/linux-2.5.37-psp04.00.00.12/arch/arm/mach-omap2/board-ti8168evm.c

AVS gets HVT/SVT and sets the AVS voltage in set_voltage(). Find this function in: /ti-ezsdk_dm816x-evm_5_02_01_59/board-support/linux-2.5.37-psp04.00.00.12/arch/arm/mach-omap2/smartreflex-ti816x.c

You can enable dynamic AVS by modifying gpio_vr_get_uv(...). Remove the if tps->current_gpio_val == 0 statement to enable dynamic AVS. This will allow the AVS to check HVT and SVT and make adjustments to the AVS every 2 seconds. Find this function in: /ti-ezsdk_dm816x-evm_5_02_01_59/board-support/linux-2.5.37-psp04.00.00.12/drivers/regulator/gpio-regulator.c. Assuming your power supply can provide the proper current, power and voltage, a working AVS should eventually work its way towards an HVT and SVT of zero. You can add reporting of HVT and SVT in smartreflex-ti816x.c/set_voltage().

Alex

Hi Alex,

I use EZSDK version 5.02.02.60.

I disabled the if statement and voltage never change.

static int gpio_vr_get_uv(struct regulator_dev *dev)
{
    struct gpio_vr_pmic *tps = rdev_get_drvdata(dev);
    u32 gpio_val;
    u32 vsel;
/*
    if (tps->current_gpio_val == 0) {
        gpio_val = gpio_read_value(tps->info.gpios,
                    tps->info.nr_gpio_pins);
        tps->current_gpio_val = gpio_val;
    }
*/
    /* Get the voltage from the table based on gpio_val */
    for (vsel = 0; vsel < tps->info.table_len; vsel++) {
        if (tps->info.table[vsel].gpio_value ==
                tps->current_gpio_val) {
            return tps->info.table[vsel].uV;
        }
    }

    return -EINVAL;
}

I am sure the driver works, because I can manually set the voltage here:

static int gpio_vr_dcdc_set_voltage(struct regulator_dev *dev,
                int min_uV, int max_uV)
{
    struct gpio_vr_pmic *tps = rdev_get_drvdata(dev);

    if (min_uV < tps->info.min_uV ||
            min_uV > tps->info.max_uV)
        return -EINVAL;
    if (max_uV < tps->info.min_uV ||
            max_uV > tps->info.max_uV)
        return -EINVAL;

    //original
    //tps->current_gpio_val = get_nearest_gpio_val(tps, min_uV);
    //return gpio_write_value(tps);

    //testing: set the AVS value manually
    tps->current_gpio_val = get_nearest_gpio_val(tps, 815000);
    return gpio_write_value(tps);

}

- Robert

Hi Anil,

2) you are right, when the AVS resistors changed, the new Pull up/down combination was set. I'll do that on my board too (GPIO0-3 used to be 1 it's 7 now). Thanks.

3) ok, I believe, this means, I just have to try to switch on/off different applications/peripherals and see what will happen ... ?

- Robert

Hi Robert,

The first part of the code you commented is required for voltage to change.

AVS driver reads the voltage from voltage regulator driver that part of the code. If you comment that portion, then AVS driver will not get the correct value so it returns invalid value.

So that device voltage will not change.

The second portion is mainly meant for setting the voltage among the range of value applicable for hardware. This API is also called from AVS driver during voltage change.

For your information:-

This statement is not correct

"You can enable dynamic AVS by modifying gpio_vr_get_uv(...). Remove the if tps->current_gpio_val == 0 statement to enable dynamic AVS."

You can enable or disable the AVS operation from debugfs entries.

Please go through this link http://processors.wiki.ti.com/index.php/DM816x_C6A816x_AM389x_AVS_Driver_Guide#Debugging_AVS_driver.

For FAQ's please go through this page

http://processors.wiki.ti.com/index.php/DM816x_C6A816x_AM389x_AVS_FAQ

Regards

Anilkumar

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Hi Robert,

3) ok, I believe, this means, I just have to try to switch on/off different applications/peripherals and see what will happen ... ?

Anil: Yes and Most of the cases I have run the application to load all the cores almost 100% and then test the stability.

Regards

Anilkumar

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Anil: Yes and Most of the cases I have run the application to load all the cores almost 100% and then test the stability.

Robert: Do you have a preffered application which you use to load cpu to 100%?

Hi Robert,

With the help of scripting we can load CPU to 100%.

By using the below command we can load CPU to 100%

$yes > /dev/null

Regards

AnilKumar

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Thank you Anil

Robert,

The intended modification was:

// if(tps->current_gpio_val == 0)

   gpio_val = gpio_read_value(tps->info.gpios, tps->info.nr_gpio_pins);

   tps->current_gpio_val = gpio_val;

// }

Sorry for the confusion.

Alex