Thread (33 messages) 33 messages, 6 authors, 2025-06-25

Re: [PATCH v12 1/7] mfd: Add core driver for Nuvoton NCT6694

From: Lee Jones <lee@kernel.org>
Date: 2025-06-13 13:11:40
Also in: linux-can, linux-gpio, linux-hwmon, linux-i2c, linux-rtc, linux-usb, linux-watchdog, lkml

On Fri, 13 Jun 2025, Ming Yu wrote:
Lee Jones [off-list ref] 於 2025年6月12日 週四 下午11:23寫道:
quoted
On Thu, 12 Jun 2025, Ming Yu wrote:
quoted
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
...
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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.
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.
Each of the devices will probe once.

The first one will be given 0, the second will be given 1, etc.

Why would you give multiple IDs to a single device bound to a driver?

-- 
Lee Jones [李琼斯]
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