Thread (16 messages) 16 messages, 5 authors, 2026-01-15

Re: [EXT] Re: [PATCH v4 2/5] dt-bindings: i3c: Add NXP P3H2x4x i3c-hub support

From: Krzysztof Kozlowski <krzk@kernel.org>
Date: 2026-01-15 21:01:09
Also in: linux-i3c, lkml

On 15/01/2026 13:21, Aman Kumar Pandey wrote:
On Tue, Jan 13, 2026 at 01:45:26PM +0200, Aman Kumar Pandey wrote: 
quoted
+https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevi
quoted
+cetree.org%2Fschemas%2Fmfd%2Fnxp%2Cp3h2840-i3c-
hub.yaml%23&data=05%7C
quoted
+02%7Caman.kumarpandey%40nxp.com%7C75a7d6f1f8b74fd3ac5808de5346
3133%7C
quoted
+686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C639039758104017624%7
CUnkno
quoted
+wn%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwM
CIsIlAiOiJX
quoted
+aW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=Ze
GSgy3cF
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+whQbcO%2BserynVrrrqYGOIwBMgVjgdY25Lg%3D&reserved=0
This is not a MFD device. Place it in appropriate place, e.g. i2c or i3c
controllers directory.
Thanks for the review and the comment.

I would like to clarify why I modeled the P3H2840 as an MFD.
I do not see any model as MFD. You placed it in MFD directory and this
is what I contest.

Otherwise please point me to any hardware description what "MFD" is,
because for sure your I3C hub is not this:
https://en.wikipedia.org/wiki/MFD - scroll down to "Multifunction
device" in "Computing".
While the primary function of the chip is an I3C hub, 
Wrap your emails so it will be possible to reply and read it.

So there you have your primary function.
this device also contains a programmable regulator which is exposed externally and can be used to power downstream devices on the board, not only the internal hub logic. This regulator has:
- Independent enable/disable control
- Independent voltage configuration

From the board and hardware point of view, this block is not only a "hub-internal" power control, but a board-level power resource that other devices depend on. 
hub logic and the regulator block have distinct roles and different Linux subsystems (I3C hub vs regulator framework), I modeled this as an MFD with two child devices.
Linux subsystems do not matter. We speak about bindings, not drivers.

You ignored some of my other comments. Your email is completely
unreadable, so answer is still NAK. Read my comments fully, fix your
email setup and then answer without all this messed quotes.

Best regards,
Krzysztof
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