Re: [PATCH v12 1/7] mfd: Add core driver for Nuvoton NCT6694
From: Ming Yu <hidden>
Date: 2025-06-12 14:41:07
Also in:
linux-can, linux-gpio, linux-hwmon, linux-i2c, linux-rtc, linux-usb, linux-watchdog, lkml
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:
...
quoted
+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.
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);
}
Best regards,
Ming