Re: [PATCH v14 4/8] mfd: p3h2x4x: Add driver for NXP P3H2x4x i3c hub and on-die regulator

[Lee Jones <lee@kernel.org>]

On Tue, 14 Jul 2026, Lakshay Piplani wrote:

> From: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
> 
> Add core MFD support for the NXP P3H2x4x (P3H2440/P3H2441/P3H2840/P3H2841)
> family of multiport I3C hub devices. These devices connect to a host via
> I3C/I2C/SMBus and expose multiple downstream target ports.
> 
> Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
> Signed-off-by: Vikash Bansal <vikash.bansal@nxp.com>
> Signed-off-by: Lakshay Piplani <lakshay.piplani@nxp.com>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> 
> ---
> Changes in v14:
>  - Clean up MFD driver comments, formatting, variable names and author
>    information
>  - Define and document the I3C hub DCR value in hexadecimal form
>  - Use direct regmap bit-width values instead of local macros
>  - Add a shared protected_reg_lock for protected register accesses across
>    P3H2X4X child drivers
> 
> Changes in v13:
>  - Use i3c_device helpers (i3cdev_to_dev()) instead of direct struct access
>    to maintain API abstraction
>  - Avoid including internal I3C headers and use public device headers instead
>  - Ensure proper device matching by relying on manufacturer ID checks in probe
> 
> Changes in v12:
>  - No change, added Reviewed-By tag
> 
> Changes in v11:
>  - Use MFD_CELL_NAME() for child device registration
>  - Rename local variables for consistency
>  - Rename driver names to follow subsystem conventions:
>    - Use '-' instead of '_' in driver names
>    - Drop the "_drv" suffix from driver names
> 
> Changes in v10:
>  - Drop redundant is_p3h2x4x_in_i3c flag
> 
> Changes in v9:
>  - Renamed macros to follow consistent uppercase naming conventions
>  - Made REGMAP selects in the P3H2X4X MFD Kconfig conditional,
>    to avoid I3C/I2C dependency issues
> 
> Changes in v8:
>  - No change
> 
> Changes in v7:
>  - Use new config I3C_OR_I2C
> 
> Changes in v6:
>  - No change
> 
> Changes in v5:
>  - Corrected the ordering in the Makefile and Kconfig for MFD_P3H2X4X
>  - Updated dev_err_probe() for regmap_init failure.
>  - Updated module description
> 
> Changes in v4:
>  - Split the driver into three separate patches(mfd, regulator and I3C hub)
>  - Added support for NXP P3H2x4x MFD functionality
> ---
> ---
>  MAINTAINERS                 |   2 +
>  drivers/mfd/Kconfig         |  13 ++++
>  drivers/mfd/Makefile        |   1 +
>  drivers/mfd/p3h2840.c       | 139 ++++++++++++++++++++++++++++++++++++
>  include/linux/i3c/device.h  |   2 +
>  include/linux/mfd/p3h2840.h |  25 +++++++
>  6 files changed, 182 insertions(+)
>  create mode 100644 drivers/mfd/p3h2840.c
>  create mode 100644 include/linux/mfd/p3h2840.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ba65ae5a008b..3420701a75c5 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19311,6 +19311,8 @@ L:	linux-kernel@vger.kernel.org
>  L:	linux-i3c@lists.infradead.org
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/i3c/nxp,p3h2840.yaml
> +F:	drivers/mfd/p3h2840.c
> +F:	include/linux/mfd/p3h2840.h
>  
>  NXP PF5300/PF5301/PF5302 PMIC REGULATOR DEVICE DRIVER
>  M:	Woodrow Douglass <wdouglass@carnegierobotics.com>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 7192c9d1d268..405b50c3c77b 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -617,6 +617,19 @@ config MFD_MX25_TSADC
>  	  i.MX25 processors. They consist of a conversion queue for general
>  	  purpose ADC and a queue for Touchscreens.
>  
> +config MFD_P3H2X4X
> +	tristate "NXP P3H2X4X I3C Hub Device"
> +	depends on I3C_OR_I2C
> +	select MFD_CORE
> +	select REGMAP_I3C if I3C
> +	select REGMAP_I2C if I2C
> +	help
> +	  Enable Support for NXP P3H244x/P3H284x I3C HUB device using I3C/I2C
> +	  communication interface.
> +
> +	  This driver provides support for I3C hub and regulator, each subdriver
> +	  can be enabled independently depending on the required functionality.
> +
>  config MFD_PF1550
>  	tristate "NXP PF1550 PMIC Support"
>  	depends on I2C=y && OF
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index e75e8045c28a..a284b22c7b13 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -122,6 +122,7 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>  
> +obj-$(CONFIG_MFD_P3H2X4X)	+= p3h2840.o
>  obj-$(CONFIG_MFD_PF1550)	+= pf1550.o
>  
>  obj-$(CONFIG_MFD_NCT6694)	+= nct6694.o
> diff --git a/drivers/mfd/p3h2840.c b/drivers/mfd/p3h2840.c
> new file mode 100644
> index 000000000000..652077408dbd
> --- /dev/null
> +++ b/drivers/mfd/p3h2840.c
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2025-2026 NXP
> + *
> + * Authors:
> + *	Aman Kumar Pandey <aman.kumarpandey@nxp.com>
> + *	Vikash Bansal <vikash.bansal@nxp.com>
> + *	Lakshay Piplani <lakshay.piplani@nxp.com>
> + *
> + * P3H2X4X multi-function device driver.

There is no such thing as an "MFD device driver".  You should describe
what the device actually is: "Multiport I3C hub device", or whatever.

If you end up re-spinning, I'd like you to change this in the next set.

If not, then please provided with a follow-up patch.

-- 
Lee Jones