Hardware Parameter Tuning Guide¶

REVISION HISTORY¶

Revison No.	Description	Date
1.0	Initial release	11/21/2023
1.1	Delete USB3.0 Replace gmac by emac/SD&eMMC merge/PAD_PM_GPIO index change	01/24/2024
1.2	add disp driving capability adjustment and clk reverse configuration	12/25/2024
1.3	add SATA CTS configuration	01/03/2025
1.4	add hdmitx driving capability adjustment and ssc adjustment	01/08/2025
1.5	add IIC & PWM driving capability adjustment	01/08/2025
1.6	add MSPI & UART driving capability adjustment	01/09/2025
1.7	add PCIe PHY parameter tuning	05/18/2026

1. Analog IP Hardware Parameter Tuning¶

1.1. USB 2.0¶

Five parameters are available for tuning, namely: pre-emphasis, slew rate, swing trim, disconnect detector reference voltage, and RX squelch calibration reference voltage (swing trim may have been trimmed in OTP, so please pay attention when adjusting this parameter).

1.1.1. pre_emphasis¶

The parameter pre_emphasis is located in UTMI bank offset 0x43[9:8]. Parameter range: 0 ~ 3. The larger the value, the stronger the pre-emphasis is.

Query the current value: cat /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/pre_emphasis
Set the value: echo value > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/pre_emphasis

1.1.2. slew_rate¶

The parameter slew_rate is located in UTMI bank offset 0x44[2:1]. Parameter range: 0 ~ 3.

Query the current value: cat /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/slew_rate
Set the value: echo value > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/slew_rate

1.1.3. swing trim (This parameter may have been trimmed in OTP, so please confirm with hardware RD before adjusting this parameter).¶

The parameter swing trim is located in UTMI bank offset 0x44[9:4]. Parameter range: 0 ~ 63.

Query the current value: cat /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/swing_trim
Set the value: echo value > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/swing_trim

1.1.4. disconnect detector reference voltage¶

The parameter disconnect detector reference voltage is located in UTMI bank offset 0x41[4:0]. Parameter range: 0 ~ 31.

Query the current value: cat /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/disconnect_refer_voltage
Set the value: echo value > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/disconnect_refer_voltage

1.1.5. RX squelch calibration reference voltage¶

The parameter RX squelch calibration reference voltage is located in UTMI bank offset 0x4b[4:0]. Parameter range: 0 ~ 31.

Query the current value: cat /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/squelch_refer_voltage
Set the value: echo value > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/squelch_refer_voltage

1.1.6. Eye Diagram Test¶

After booting the device, enter the kernel and run the following commands, and then you can connect with an oscilloscope to view the eye diagram.
When the waveform result of eye diagram test does not meet the requirements, you can adjust the above five parameters until the waveform is perfect.

To perform highspeed eye diagram test, run: echo “hs” > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/eye_diagram_switch

To perform fullspeed eye diagram test, run: echo “fs” > /sys/kernel/debug/usb/phy-soc\:u2phy0@0x1f284200.0/eye_diagram_switch

1.2. USB 3.0¶

mHera USB3.0 Port 3 uses PIPE PHY, and Port 2 uses SUPPHY. Each has different driving capability parameters.

1.2.1. Port 3 - PIPE PHY¶

Three parameters are available for PIPE PHY tuning: idrv (drive current), idem (de-emphasis) and biasi (bias current).

1.2.1.1. idrv (TX Drive Current)¶

Located at PHYD Offset 0x41[7:2], range: 0~63. Higher value means stronger drive current.

Query current idrv level: cat /sys/kernel/debug/usb/phy-1f2a5200.pipe.6/tx-idrv

Set idrv level: echo level > /sys/kernel/debug/usb/phy-1f2a5200.pipe.6/tx-idrv

1.2.1.2. idem (TX De-Emphasis)¶

Located at PHYD Offset 0x41[13:8], range: 0~63. Higher value means stronger de-emphasis.

Query current idem level: cat /sys/kernel/debug/usb/phy-1f2a5200.pipe.6/tx-idem

Set idem level: echo level > /sys/kernel/debug/usb/phy-1f2a5200.pipe.6/tx-idem

1.2.1.3. biasi (TX Bias Current)¶

Located at PHYD Offset 0x26[3:1], range: 0~7. Higher value means larger bias current.

Query current biasi level: cat /sys/kernel/debug/usb/phy-1f2a5200.pipe.6/tx-biasi

Set biasi level: echo level > /sys/kernel/debug/usb/phy-1f2a5200.pipe.6/tx-biasi

1.2.2. Port 2 - SUPPHY¶

Three parameters are available for SUPPHY tuning: swing-mode (swing mode selection), swing-amplitude (low-swing amplitude) and tx-deemphasis (TX de-emphasis).

1.2.2.1. swing-mode (Swing Mode Selection)¶

Located at PHYD Offset 0x02[1:0], used to switch between Full-Swing and Low-Swing modes.

Value	Mode
2	Full-Swing
3	Low-Swing

Query current mode: cat /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/swing-mode

Switch to Low-Swing mode: echo 3 > /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/swing-mode

Switch to Full-Swing mode: echo 2 > /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/swing-mode

1.2.2.2. swing-amplitude (Low-Swing Amplitude)¶

Configure the SUPPHY low-swing amplitude level. Only configurable and readable in Low-Swing mode. Located at PHYD Offset 0x10[7:0], controlled by level value 0~5.

Level	Register Value	Description
0	0x6C	-1.5dB (84%)
1	0x60	-2.5dB (75%)
2	0x56	-3.5dB (67%)
3	0x4D	-4.5dB (60%)
4	0x40	-6dB (50%)
5	0x36	-7.6dB (42%)

Query current level: cat /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/swing-amplitude

Set level: echo 3 > /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/swing-amplitude

1.2.2.3. tx-deemphasis (TX De-Emphasis Amplitude)¶

Located at PHYD Offset 0x02[7:6] (amplitude) and PHYD Offset 0x03[8] (enable), range: 0~2. Writing any value automatically enables de-emphasis (PHYD 0x03[8]=1).

Value	De-Emphasis
0	-6dB
1	-3.5dB
2	0dB

Query current tx-deemphasis value: cat /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/tx-deemphasis

Set tx-deemphasis value: echo value > /sys/kernel/debug/usb/phy-1f2b2600.pipe.7/tx-deemphasis

1.3. SDMMC Driving Capability Configuration¶

1.3.1. Driving Capability Configured by sysfs¶

SDMMC driver provides sysfs control pin driving capability, please refer to the following instruction:

1. cd /sys/devices/soc0/soc/<reg>:sgs_sdmmc[i]
2. # <reg> - Generate Reg value based on the actual configuration information of DTSI
3. # [i]   - Generate index value based on the actual configuration information of DTSI
4. echo [slotNo] <signal> [level] > set_sdmmc_driving_control
5. # Set driving capability as [level] for the signal line <signal> of [slotNo].
6. # [slotNo] - Select the slot to be operated.
7. # <signal> - You may choose to set clk, cmd, data, all, or null (equal to all).
8. # [level]  - driving capability level. Value range: 0 ~ 7.

Set the driving capability of all signal pins of sd to 2

1. cd /sys/devices/platform/soc/1f282600.sgs_sdmmc1
2. echo 0 all 2 > set_sdmmc_driving_control

Set the driving capability of the four data pins of emmc to 1:

1. cd /sys/devices/platform/soc/1f282000.sgs_sdmmc0
2. echo 1 data 1 > set_sdmmc_driving_control

1.3.2. Driving Capability Configured by dts¶

SDMMC driver supports configuring the driving capabilities of clk, cmd and data signal lines from dts. The configuration is as follows:

1. sgs_sdmmc0: sgs_sdmmc0 {
2.     compatible = "sgs,sdmmc";
3.     bus-width = <4>;
4.     no-sdio;
5.     no-sd;
6.     …
7.     clk-driving = <2>,<0>,<0>;
8.     cmd-driving = <2>,<0>,<0>;
9.     data-driving = <2>,<0>,<0>;
10.    …
11. }

1. sgs_sdmmc1: sgs_sdmmc1 {
2.     compatible = "sgs,sdmmc";
3.     bus-width = <4>;
4.     no-mmc;
5.     …
6.     clk-driving = <2>,<0>,<0>;
7.     cmd-driving = <2>,<0>,<0>;
8.     data-driving = <2>,<0>,<0>;
9.    …
10. }

As shown above, these three attribute parameters configure the driving capabilities of the clk line, cmd line and four data lines, respectively. You can see that each parameter has three values. These three values represent the driving capability of each slot. The driving level is determined by the actual selected PAD. For details, please refer to the relevant GPIO PAD configuration document.

1.4. DISP¶

1.4.1. Driving Capability Adjustment¶

DISP driver supports configuraing the driving capability of the panel pin from the screen parameters. The configuration is as follows:

1、configure padmux

padmux file path:

#arm32
kernel/arch/arm/boot/dts/$(boardname)-padmux.dtsi
#arm64
kernel/arch/arm64/boot/dts/sgs/$(boardname)-padmux.dtsi

Change padmux #if 0 to #if 1 based on the interface currently required.

2、set m_wPadDrvngLvl on the screen parameters

screen parameters path:

project\board\$(chip)\screen_param\config_disp.json

m_wPadDrvngLvl
0: 4mA
1: 8mA
2: 12mA
3: 16mA

Add and configure m_wPadDrvngLvl in the screen parameters, and run disp again to display the diagram. The driving level of the pin can be uniformly adjusted.

The configurable driving levels of different pins may vary. For details, please refer to the relevant GPIO PAD configuration document.

3、VGA driving capability config/detect

Config driving capability:

echo vga_drv RTrim GTrim BTrim > /proc/mi_modules/mi_disp/debug_hal/turndrv

Detect driving capability:

cat /proc/mi_modules/mi_disp/debug_hal/turndrv

RTrim/GTrim/BTrim value range is 0x00 ~ 0x7F. The larger the value, the greater the driving capability.

1.4.2. clk positive and negative configuration¶

screen parameters path:

project\board\$(chip)\screen_param\config_disp.json

m_bPanelInvDCLK
0: default
1: reverse

Configure m_bPanelInvDCLK in the screen parameters, and run disp again to display the diagram. The forward and reverse direction of the clk can be adjusted.

1.5. SATA¶

1.5.1. HW CTS Setting¶

Perform SATA PHY layer signal quality tuning via the Sysfs interface. The confirmed parameters must be updated to the dts before the SATA driver will apply the adjusted CTS parameters.

Sysfs path: /sys/devices/virtual/sgs/sata or sata1

Note: The transmission speed (test_gen) must be set before the test pattern (cts_pattern), because the PHY driver needs speed information to correctly force speed when entering CTS pattern.

a. Set Transmission Speed (test_gen)

test_gen	Speed	Description
0	1.5 Gbps	SATA GEN1
1	3.0 Gbps	SATA GEN2
2	6.0 Gbps	SATA GEN3

echo [test_gen] > test_gen

b. Set Test Pattern (cts_pattern)

cts_pattern	Pattern Name	Description
0	HFTP	High Frequency Test Pattern
1	MFTP	Mid Frequency Test Pattern
2	LFTP	Low Frequency Test Pattern
3	LBP	Low Bit Pattern
4	SSOP	Spread Spectrum Oscillation Pattern

echo [cts_pattern] > cts_pattern

c. Set TX Parameters (de_emphasis)

TX parameters include De-emphasis and voltage swing (Vpp) for signal quality optimization:

echo [enable] [db] [level] > de_emphasis

Parameter	Description	Available Values
`enable`	GEN3 de-emphasis enable	0=Vpp only, 1=enable de-emphasis
`db`	De-emphasis level (only for enable=1)	0=-1.5dB, 1=-2.5dB, 2=-3.5dB, 3=-6.0dB
`level`	Voltage swing level	0~8, see table below

Voltage swing (Vpp) levels and GEN support:

level	Voltage Swing	GEN1	GEN2	GEN3
0	0.4 Vpp	Yes	Yes	Yes
1	0.5 Vpp	Yes	Yes	Yes
2	0.6 Vpp	Yes	Yes	Yes
3	0.7 Vpp	Yes	Yes	Yes
4	0.8 Vpp	Yes	Yes	Yes
5	0.9 Vpp	-	Yes	Yes
6	1.0 Vpp	-	-	Yes
7	1.1 Vpp	-	-	Yes
8	1.2 Vpp	-	-	Yes

GEN1/GEN2 only support Vpp adjustment. De-emphasis is only available in GEN3 mode.

Configuration examples:

# GEN3: Vpp only (no de-emphasis), 0.7Vpp
echo 0 0 3 > de_emphasis

# GEN3: -2.5dB de-emphasis + 0.8Vpp (medium distance)
echo 1 1 4 > de_emphasis

# GEN3: -6.0dB de-emphasis + 1.0Vpp (long distance)
echo 1 3 6 > de_emphasis

1.5.2. Hardware Parameter Configured by dts¶

The optimal parameters confirmed by CTS testing must be updated to the dts. The Sysfs command echo [enable] [db] [level] > de_emphasis maps directly to the DTS parameter tx_gen3_de_emphasis = <enable>, <db>, <level>. The value 0xFF means use default.

sgs_sataphy: sgs-sata-phy {
    compatible = "sgs,sataphy";
    …
    phy_mode = <2>;                              /* PHY speed mode: 0=GEN1, 1=GEN2, 2=GEN3 */
    tx_ssc_mode = <0>;                           /* Spread spectrum clock: 0=disable, 1=enable */
    tx_gen1_gen2_Vpp = <0xFF>,<0xFF>;            /* GEN1/GEN2 TX voltage swing, 0xFF=default */
    tx_gen3_de_emphasis = <0xFF>,<0xFF>,<0xFF>;  /* GEN3: <enable>,<db>,<level>, 0xFF=default */
    rx_eq_rs1 = <0xFF>,<0xFF>,<0xFF>;            /* RX equalization RS1, 0xFF=default */
    rx_eq_rs2 = <0xFF>,<0xFF>,<0xFF>;            /* RX equalization RS2, 0xFF=default */
    rx_eq_ctle = <0xFF>;                         /* RX equalization CTLE, 0xFF=default */
    …
};

DTS configuration examples:

/* Example 1: GEN3 with -2.5dB de-emphasis + 0.8Vpp */
tx_gen3_de_emphasis = <1>, <1>, <4>;

/* Example 2: GEN3 Vpp only (no de-emphasis), 0.7Vpp */
tx_gen3_de_emphasis = <0>, <0xFF>, <3>;

/* Example 3: GEN1/GEN2 Vpp, two values for GEN1 and GEN2 respectively */
tx_gen1_gen2_Vpp = <3>, <3>;   /* GEN1=0.7Vpp, GEN2=0.7Vpp */

1.6. HDMITX¶

1.6.1. Driving Capability Adjustment¶

HDMITX driver supports configuraing the driving capability by "echo" cmd. The configuration is as follows:

echo Tap1Ch0 Tap1Ch1 Tap1Ch2 Tap1Ch3 Tap2Ch0 Tap2Ch1 Tap2Ch2 Tap2Ch3 RetrmCh PreDrvCh MuCh > /proc/mi_modules/mi_hdmi/debug_hal/turndrv

Get driving config:

cat /proc/mi_modules/mi_hdmi/debug_hal/turndrv

1.6.2. SSC¶

Spread spectrum setting supports auto & manual by "echo" cmd.

The auto adjustment is as follows:

echo ssc $en auto Modulation(hz) Deviation(%) > /proc/mi_modules/mi_hdmi/debug_hal/turndrv

The manual adjustment is as follows:

echo ssc $en manual STEP(0x) SAPN(0x) > /proc/mi_modules/mi_hdmi/debug_hal/turndrv

Get adjustment parameters as follows:

cat /proc/mi_modules/mi_hdmi/debug_hal/turndrv

1.7. IIC¶

1.7.1. Configuration of IIC Drive Capability¶

The drive capability of IIC is influenced by both the drive strength of the GPIO used and the IIC IP settings. The configuration method for the former can refer to the GPIO debugging methods, while adjustments for the latter are as follows;

The IIC IP provides four configurable settings related to drive capability, as shown in the following table:

Mode Num	Mode Name	description
Mode 1	Pure Open drain	Pure open-drain output without auxiliary drive; this results in the slowest rise time
Mode 2	PUSH EN	Auxiliary drive for 1 T, the rise time is faster than Mode 1
Mode 3	PUSH EN M+	Auxiliary drive for 16 T, the rise time is faster than Mode 2
Mode 4	PUSH PULL	Push-pull output mode, this results in a faster rise time

The IIC IP drive capability needs to be configured in the IIC node within the dtsi file, with the file path being:

#arm32
kernel/arch/arm/boot/dts/$(boardname).dtsi
#arm64
kernel/arch/arm64/boot/dts/sgs/$(boardname).dtsi

The node properties are as follows. Modify the output-mode to the target mode and then compile to change the IIC IP output mode configuration:

        i2c0: i2c@1f223000 {
                compatible = "sgs,i2c";
                reg = <0x1F223000 0x200>;
                #address-cells = <1>;
                #size-cells = <0>;
                interrupts = <GIC_SPI INT_IRQ_MIIC_0 IRQ_TYPE_LEVEL_HIGH>;
                clocks = <&CLK_miic0>;
                dma-enable;
                group = <0>;
                speed = <200000>;
                //if u want set tSU/tHD, it should be set to a non-zero value, with units in ns
                t-su-sta = <0>;
                t-hd-sta = <0>;
                t-su-sto = <0>;
                t-hd-sto = <0>;
                //1->open drain; 2->open drain + one push; 3->open drain + mult push; 4->push-pull
                output-mode = <2>;
                status = "okay";
            };

1.8. PWM¶

1.8.1. Adjustment of PWM Drive Capability¶

The drive capability of PWM is influenced by the GPIO it uses; the configuration method for the latter can refer to the GPIO debugging methods.

1.9. MSPI¶

1.9.1. Adjustment of MSPI Drive Capability¶

The drive capability of MSPI is influenced by the GPIO it uses; the configuration method for the latter can refer to the GPIO debugging methods.

1.10. UART¶

1.10.1. Adjustment of UART Drive Capability¶

The drive capability of UART is influenced by the GPIO it uses; the configuration method for the latter can refer to the GPIO debugging methods.

1.11. PCIe¶

PCIe PHY signal parameters can be tuned at runtime through the debugfs interface for signal quality debugging. Prerequisite: the kernel must have CONFIG_DEBUG_FS enabled.

The debugfs nodes are located at /sys/kernel/debug/pcie\<port>/, where \<port> is the PCIe port number (0 or 1).

1.11.1. swing_mode (Swing Mode)¶

Configure the PCIe transmitter swing mode.

Value	Description
0	Full-swing
1	Low-swing

Query the current value: cat /sys/kernel/debug/pcie0/swing_mode
Set the value: echo 1 > /sys/kernel/debug/pcie0/swing_mode

1.11.2. swing_amplitude (Swing Amplitude)¶

Configure the PCIe transmitter swing amplitude gear. Only configurable and readable in Low-swing mode. PCIe has two lanes, and the configuration applies to both lanes simultaneously.

Gear	Register Value	Description
0	0x6C	-1.5dB (84%)
1	0x60	-2.5dB (75%)
2	0x56	-3.5dB (67%)
3	0x4D	-4.5dB (60%)
4	0x40	-6dB (50%)
5	0x36	-7.6dB (42%)

Query the current value: cat /sys/kernel/debug/pcie0/swing_amplitude
Set the value: echo 3 > /sys/kernel/debug/pcie0/swing_amplitude

1.11.3. de_emphasis_us (De-emphasis - Upstream Port)¶

Configure the de-emphasis parameter for the PCIe upstream port (EP mode). Only configurable and readable in Full-swing mode, and only visible in EP mode.

Value	Description
0	-6dB
1	-3.5dB

Query the current value: cat /sys/kernel/debug/pcie0/de_emphasis_us
Set the value: echo 1 > /sys/kernel/debug/pcie0/de_emphasis_us

1.11.4. de_emphasis_ds (De-emphasis - Downstream Port)¶

Configure the de-emphasis parameter for the PCIe downstream port (RC mode). Only configurable and readable in Full-swing mode, and only visible in RC mode.

Value	Description
0	-6dB
1	-3.5dB

Query the current value: cat /sys/kernel/debug/pcie0/de_emphasis_ds
Set the value: echo 1 > /sys/kernel/debug/pcie0/de_emphasis_ds

1.11.5. status (Status Overview)¶

Display all current PHY parameter configurations in read-only mode.

cat /sys/kernel/debug/pcie0/status

2. Digital Interface Driving Capability Adjustment¶

2.1. Usage Background¶

Since GPIO lib does not support interfaces for GPIO pull-up, pull-down and driving capability adjustment, our GPIO Hal layer driver lacks the support of GPIO pull-up, pull-down and driving capability setting. In daily use, however, the GPIO pull-up, pull-down and driving capability often need to be dynamically adjusted, so it is necessary to add APIs as well as user-level interfaces for these setting.

2.2. Kernel Interface¶

2.2.1. sgs_gpio_pull_up¶

Objective

Enable the pull-up function of a specified GPIO.
Syntax
```
U8 sgs_gpio_pull_up(U8 gpio_index)
```
Parameter

Parameter Description

gpio index gpio num
Return Value

Return Value Description

0 Setting successful.

Other The pin does not support pull-up and pull-down settings or the input parameter is incorrect.

2.2.2. sgs_gpio_pull_down¶

Objective

Enable the pull-down function of a specified GPIO.
Syntax
```
U8 sgs_gpio_pull_down(U8 gpio_index)
```
Parameter

Parameter Description

gpio index gpio num
Return Value

Return Value Description

0 Setting successful.

Other The pin does not support pull-up and pull-down settings or the input parameter is incorrect.

2.2.3. sgs_gpio_pull_off¶

Objective

Disable the pull-up/pull-down function of a specified GPIO, and switch the GPIO to no-pull state.
Syntax
```
U8 sgs_gpio_pull_off(U8 gpio_index)
```
Parameter

Parameter Description

gpio index gpio num
Return Value

Return Value Description

0 Setting successful.

Other The pin does not support pull-up and pull-down settings or the input parameter is incorrect.

2.2.4. sgs_gpio_drv_set¶

Objective

Set driving capability of a specified GPIO.

Syntax

U8 sgs_gpio_drv_set(U8 gpio_index, U8 level)

Parameter

Parameter Description

gpio index gpio num

level The level of supported driving capability: 0, 1, 2, 3...
Return Value

Return Value Description

0 Setting successful.

Other The pin does not support pull-up and pull-down settings or the input parameter is incorrect.

2.3. User-Level Tuning Guide¶

2.3.1. Enable the Function¶

To use the user-level interface, you need to enable CONFIG_MSYS_GPIO, the configuration is located in menuconfig:

Device Drivers
    sgs SoC platform drivers
        msys api
            support GPIO pull and driving modify

2.3.2. Use the Function¶

Before setting the pull-up/pull-down, you need to set the GPIO to the input state. The pull-up and pull-down cannot be measured in the output state:

1. # cd /sys/class/gpio
2. # echo gpio_index > export
3. # echo in > gpiogpio_index/direction

Set pull-up, pull-down, or no-pull:

1. # cd sys/class/sgs/msys
2. # echo gpio_index/gpio_name down/up/off > gpio_pull

Check the current state:

1. # cd sys/class/sgs/msys
2. # cat gpio_pull

Using PAD_PM_GPIO0 as an example, set it to input state:

1. # cd /sys/class/gpio
2. # echo 71 > export
3. # echo in > gpio71/direction

Set it to pull-up:

1. # cd sys/class/sgs/msys
2. # echo 71 up > gpio_pull
3. # echo PAD_PM_GPIO0 up > gpio_pull //the same to above

Set it to no-pull:

1. # cd sys/class/sgs/msys
2. # echo 71 off > gpio_pull
3. # echo PAD_PM_GPIO0 off > gpio_pull //the same to above

Check the current state:

1. # cd sys/class/sgs/msys
2. # cat gpio_pull

Before setting the driving capability, you need to set the GPIO to high level output state to facilitate measurement:

1. # cd /sys/class/gpio
2. # echo gpio_index > export
3. # echo high > gpiogpio_index/direction

Adjust the driving capability:

1. # cd sys/class/sgs/msys
2. # echo gpio_index/gpio_name level_num > gpio_drive

Set PAD_PM_GPIO0 to 8mA as an example:

1. # cd /sys/class/gpio
2. # echo 71 > export
3. # echo high > gpio71 /direction
4. # cd sys/class/sgs/msys
5. # echo 71 1 > gpio_drive
6. # echo PAD_PM_GPIO0 1 > gpio_drive //the same to above

Every time after echo command is executed, you can confirm the status of the previous echo command by cat the same file.

Return Value	Description
0	Setting successful.
Other	The pin does not support pull-up and pull-down settings or the input parameter is incorrect.

Parameter	Description
gpio index	gpio num
level	The level of supported driving capability: 0, 1, 2, 3...