Hi Lee,
On Tue, 3 Sep 2024 16:38:39 +0100
Lee Jones <lee@xxxxxxxxxx> wrote:
> On Thu, 08 Aug 2024, Herve Codina wrote:
>
> > From: Clément Léger <clement.leger@xxxxxxxxxxx>
> >
> > 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 <clement.leger@xxxxxxxxxxx>
> > Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> > ---
> > 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?
>
Existing user don't use devm_syscon_regmap_lookup_by_phandle() nor
syscon_put_regmap().
So refcount is incremented but never decremented. syscon is never
released. Exactly the same as current implementation.
Nothing change for existing users.
Best regards,
Hervé
