Re: [PATCH] gpio: tegra186: Support multi-socket devices

[Jon Hunter <jonathanh@nvidia.com>]

On 16/02/2026 11:29, Bartosz Golaszewski wrote:
> On Mon, 16 Feb 2026 05:58:42 +0100, Prathamesh Shete <pshete@nvidia.com> said:
>> On Tegra platforms, multiple SoC instances may be present with each
>> defining the same GPIO name. For such devices, this results in
>> duplicate GPIO names.
>>
>> When the device has a valid NUMA node, prepend the NUMA node ID
>> to the GPIO name prefix. The node ID identifies each socket,
>> ensuring GPIO line names remain distinct across multiple sockets.
>>
>> Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
>> ---
>>   drivers/gpio/gpio-tegra186.c | 26 +++++++++++++++++---------
>>   1 file changed, 17 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-tegra186.c b/drivers/gpio/gpio-tegra186.c
>> index 9c874f07be75..daf5aaffa28a 100644
>> --- a/drivers/gpio/gpio-tegra186.c
>> +++ b/drivers/gpio/gpio-tegra186.c
>> @@ -857,7 +857,8 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
>>   	struct device_node *np;
>>   	struct resource *res;
>>   	char **names;
>> -	int err;
>> +	char *instance = "";
>> +	int node, err;
>>
>>   	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
>>   	if (!gpio)
>> @@ -937,17 +938,21 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
>>   	if (!names)
>>   		return -ENOMEM;
>>
>> +	node = dev_to_node(&pdev->dev);
>> +	if (node >= 0) {
>> +		instance = devm_kasprintf(gpio->gpio.parent, GFP_KERNEL, "%d-", node);
> 
> I've never noticed it before (and it's not introduced by this patch) but I
> really dislike the child device registering devres nodes with its parent...
> 
>> +		if (!instance)
>> +			return -ENOMEM;
>> +	}
>> +
>>   	for (i = 0, offset = 0; i < gpio->soc->num_ports; i++) {
>>   		const struct tegra_gpio_port *port = &gpio->soc->ports[i];
>>   		char *name;
>>
>>   		for (j = 0; j < port->pins; j++) {
>> -			if (gpio->soc->prefix)
>> -				name = devm_kasprintf(gpio->gpio.parent, GFP_KERNEL, "%s-P%s.%02x",
>> -						      gpio->soc->prefix, port->name, j);
>> -			else
>> -				name = devm_kasprintf(gpio->gpio.parent, GFP_KERNEL, "P%s.%02x",
>> -						      port->name, j);
>> +			name = devm_kasprintf(gpio->gpio.parent, GFP_KERNEL, "%s%sP%s.%02x",
>> +					      instance ?: "", gpio->soc->prefix ?: "",
> 
> instance can't be NULL here, can it? Either print it unconditionally or
> initialize it to NULL.

The other alternative here is that we just use 'instance' without the 
ternary operator because we initialise to "" ...

  name = devm_kasprintf(gpio->gpio.parent, GFP_KERNEL, "%s%sP%s.%02x",
                        instance, gpio->soc->prefix ?: "",
                        port->name, j);

Jon

-- 
nvpublic