Re: [PATCH v4 3/3] i3c: add i3cdev module to expose i3c dev in /dev

From: Meagan Lloyd <meaganlloyd@linux.microsoft.com>
To: Sam Agazaryan <samagazaryan@google.com>
Cc: linux-i3c@lists.infradead.org,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Frank Li <Frank.Li@nxp.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Vitor Soares <vitor.soares@toradex.com>,
	Oleksandr Shulzhenko <oleksandr.shulzhenko.viktorovych@intel.com>,
	linux-kernel@vger.kernel.org, tgopinath@linux.microsoft.com,
	boris.brezillon@collabora.com
Subject: Re: [PATCH v4 3/3] i3c: add i3cdev module to expose i3c dev in /dev
Date: Fri, 11 Sep 2026 15:05:56 -0700	[thread overview]
Message-ID: <20260911-d0e2d97df458cbf24fa42089@linux.microsoft.com> (raw)
In-Reply-To: <20260906202747.4041389-4-samagazaryan@google.com>

FYI, I have an alternative design option that's worth reviewing:
https://lore.kernel.org/linux-i3c/20260911210935.1353126-1-meaganlloyd@linux.microsoft.com/T/#mcec3e06c911d331d5cd2b2d0a7f7169b5f9f044b

It follows in the direction Boris was going in the 2020 thread:
https://lore.kernel.org/linux-i3c/20200222093844.2f5ed538@collabora.com/

The alternate binding solution is:

If i3cdev match id table is empty, the generic i3cdev driver can't bind
during the auto-loading that happens on boot. This means we won't step
on the toes of more specialized drivers. Once user-space sets
driver_override sysfs knob to 'i3cdev' and binds the device to i3cdev,
it behaves the same as any other typical driver model-based driver. We
can also use udev rules to automate setting the driver_override & doing
the bind for any i3c devices found by the core.

My series also implements actual_len in the controller drivers and uses
it as an output for user-space to consume for reads. It also accounts for
maintaining compatibility if i3cdev_xfer struct expands for HDR modes.

- Meagan

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