Lee Jones [off-list ref] 於 2025年6月12日 週四 下午11:23寫道：

On Thu, 12 Jun 2025, Ming Yu wrote:

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Dear Lee,

Thank you for reviewing,

Lee Jones [off-list ref] 於 2025年6月12日 週四 下午10:00寫道：

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...

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+static const struct mfd_cell nct6694_devs[] = {
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 0),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 1),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 2),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 3),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 4),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 5),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 6),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 7),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 8),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 9),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 10),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 11),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 12),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 13),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 14),
+     MFD_CELL_BASIC("nct6694-gpio", NULL, NULL, 0, 15),
+
+     MFD_CELL_BASIC("nct6694-i2c", NULL, NULL, 0, 0),
+     MFD_CELL_BASIC("nct6694-i2c", NULL, NULL, 0, 1),
+     MFD_CELL_BASIC("nct6694-i2c", NULL, NULL, 0, 2),
+     MFD_CELL_BASIC("nct6694-i2c", NULL, NULL, 0, 3),
+     MFD_CELL_BASIC("nct6694-i2c", NULL, NULL, 0, 4),
+     MFD_CELL_BASIC("nct6694-i2c", NULL, NULL, 0, 5),

Why have we gone back to this silly numbering scheme?

What happened to using IDA in the child driver?

In a previous version, I tried to maintain a static IDA in each
sub-driver. However, I didn’t consider the case where multiple NCT6694
devices are bound to the same driver — in that case, the IDs are not
fixed and become unusable for my purpose.

Not sure I understand.

As far as I know, if I maintain the IDA in the sub-drivers and use
multiple MFD_CELL_NAME("nct6694-gpio") entries in the MFD, the first
NCT6694 device bound to the GPIO driver will receive IDs 0~15.
However, when a second NCT6694 device is connected to the system, it
will receive IDs 16~31.
Because of this behavior, I switched back to using platform_device->id.

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I’ve since realized that using pdev->id avoids the need for cell->id,
so I reverted to the earlier approach.

That said, do you think it would be a better solution to manage all
the IDAs centrally within the driver? For example:
in nct6694.c
struct nct6694 {
    struct device *dev;

    struct ida gpio_ida;
    struct ida i2c_ida;
    struct ida can_ida;
    struct ida wdt_ida;
};

static int nct6694_probe(struct platform_device *pdev)
{
    ida_init(&nct6694->gpio_ida);
    ...
}

in gpio-nct6694.c
static int nct6694_gpio_probe(struct platform_device *pdev)
{
    id = ida_alloc(&nct6694->gpio_ida, GFP_KERNEL);
}

No that would be way worse.

Thanks,
Ming