Subject: Re: [PATCH v5 3/8] mfd: syscon: Add reference counting and device managed support

From: Lee Jones <[email-masked]>
Date: Tue, 3 Sep 2024 16:38:39 +0100

On Thu, 08 Aug 2024, Herve Codina wrote:

> From: Clément Léger <[email-masked]>
> 
> Syscon releasing is not supported.
> Without release function, unbinding a driver that uses syscon whether
> explicitly or due to a module removal left the used syscon in a in-use
> state.
> 
> For instance a syscon_node_to_regmap() call from a consumer retrieves a
> syscon regmap instance. Internally, syscon_node_to_regmap() can create
> syscon instance and add it to the existing syscon list. No API is
> available to release this syscon instance, remove it from the list and
> free it when it is not used anymore.
> 
> Introduce reference counting in syscon in order to keep track of syscon
> usage using syscon_{get,put}() and add a device managed version of
> syscon_regmap_lookup_by_phandle(), to automatically release the syscon
> instance on the consumer removal.
> 
> Signed-off-by: Clément Léger <[email-masked]>
> Signed-off-by: Herve Codina <[email-masked]>
> ---
>  drivers/mfd/syscon.c       | 138 ++++++++++++++++++++++++++++++++++---
>  include/linux/mfd/syscon.h |  16 +++++
>  2 files changed, 144 insertions(+), 10 deletions(-)

This doesn't look very popular.

What are the potential ramifications for existing users?

-- 
Lee Jones [李琼斯]