Linux/TMDXIDK5718: Setting GPIO in SPL

Christian Leeb

Part Number: TMDXIDK5718

Tool/software: Linux

Using Linux SDK 5.2 I'm trying to set a GPIO (GPIO4, bit 16) in SPL. In U-boot it works fine: I do " gpio set gpio@4805900016".

Now I try in U-boot SPL (using code from cmd/gpio.c)

rc = gpio_lookup_name("gpio@4805900016", NULL, NULL, &gpio);

this function returns -22. So I dug depper and found that this function is calling

int dm_gpio_lookup_name(const char *name, struct gpio_desc *desc)
{
struct gpio_dev_priv *uc_priv = NULL;
struct udevice *dev;
ulong offset;
int numeric;
int ret;

numeric = isdigit(*name) ? simple_strtoul(name, NULL, 10) : -1;
for (ret = uclass_first_device(UCLASS_GPIO, &dev); dev; ret = uclass_next_device(&dev)) {
int len;

uc_priv = dev_get_uclass_priv(dev);

....

I found out that "uclass_first_device(UCLASS_GPIO, &dev);" sets "dev" to 0 and then the function returns -EINVAL. So it seems that not a singe UCLASS_GPIO devices is registered.

In the device tree I have set:

&gpio4 {
u-boot,dm-spl;
};

So I would expect that at least this GPIO should be in the list..

What am I doing wrong?

Best regards, Chris

over 7 years ago

0 Dwarakesh Radhakrishnan over 7 years ago

Guru 13660 points

Hi Christian Leeb,

Can you check if spl is having the following config enabled (configs/am57xx_evm_defconfig) ?

1. CONFIG_SPL_OF_CONTROL=y
2. CONFIG_SPL_DM=y
3. CONFIG_DM_GPIO=y

0 Christian Leeb over 7 years ago in reply to Dwarakesh Radhakrishnan

Expert 1690 points

Yes, it's all set.

Regards, Chris

0 Dwarakesh Radhakrishnan over 7 years ago in reply to Christian Leeb

Guru 13660 points

Hi Christian Leeb,

Here are few suggestions to debug
1. Add print log to check if omap_gpio_probe() is called in drivers/gpio/omap_gpio.c
2. You can add dm-spl to dts node gpio@48059000 in dtsi file
3. Offset you can pass as gpio@48059016 , instead of "gpio@4805900016" to gpio_lookup_name()
4. use fdtdump tool or similar to check dtb entries linked to spl binary (or can strip off from spl binary)

My suspicion is gpio node entry is not added to stripped down version of dtb for spl.

0 Christian Leeb over 7 years ago in reply to Dwarakesh Radhakrishnan

Expert 1690 points

Hi Dwarakesh,

No success:

1. I checked with debugger that all GPIOs are probed (omap_gpio_probe()).
2. As fdtdumtp shows, gpio@48059000 is in SPL DT
3. Did not help.
4. fdtdump -s MLO shows that all GPIOs are in the SPL DT

...
gpio@48059000 {
compatible = "ti,omap4-gpio";
reg = <0x48059000 0x000000ae>;
interrupts = <0x00000000 0x00000006 0x00000003>;
ti,hwmods = "gpio4";
gpio-controller;
#gpio-cells = <0x00000002>;
interrupt-controller;
#interrupt-cells = <0x00000002>;
status = "okay";
u-boot,dm-spl;
};
...

BR, Chris

0 Dwarakesh Radhakrishnan over 7 years ago in reply to Christian Leeb

Guru 13660 points

Can you check at what point it fails in function:

uclass_find();

I am wondering now if the entry is removed by some means, not sure though. Have you seen the same behavior in uboot(removing dm-spl ) ?

0 Christian Leeb over 7 years ago in reply to Dwarakesh Radhakrishnan

Expert 1690 points

does not get any memory here:

BR., Chris

0 Dwarakesh Radhakrishnan over 7 years ago in reply to Christian Leeb

Guru 13660 points

Hi,
Looks like you have debugger:

1. Can you memory watch gd and gd->dm_root ?
2. gd->dm_root should be assigned in dm_init in file drivers/core/root.c. Please see if there is any deinit happening ?

0 Christian Leeb over 7 years ago in reply to Dwarakesh Radhakrishnan

Expert 1690 points

I found out that calloc is called before dm_init. So this explains the behaviour.

dm_init() is called in spl_early_init().

I called the failing "gpio_lookup_name("gpio@4805900016", NULL, NULL, &gpio);" in "do_board_detect()", the one that is called by SPL to read the board EEPROM. So it seems that this is done before spl_early_init()

save_omap_boot_params();
#endif
do_board_detect();
#ifdef CONFIG_SPL_BUILD
spl_early_init();
#endif
vcores_init();
#ifdef CONFIG_DEBUG_UART_OMAP
debug_uart_init();
#endif

Do you think it's viable to move spl_early_init() before do_board_detect()

Background is that on our custom HW EEPROM is behind an I2C mux which is tied to reset until I assert a specific GPIO.

BR. Chris

0 Dwarakesh Radhakrishnan over 7 years ago in reply to Christian Leeb

Guru 13660 points

Hi Chris,

Good to know you were able to narrow it down.

I think it should be fine to move spl_early_init() above. do_board_detect() gets board info in sysinfo.board_string and this string is not being used in AM57xx SoC anywhere. Hence I believe it should be fine for this SoC.

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Linux/TMDXIDK5718: Setting GPIO in SPL