Re: [PATCH 2/3] mfd: rohm-bd71828: Use software nodes for gpio-keys

[Matti Vaittinen]

On 18/08/2025 09:54, Matti Vaittinen wrote:
> On 18/08/2025 01:47, Dmitry Torokhov wrote:
> > Refactor the rohm-bd71828 MFD driver to use software nodes for
> > instantiating the gpio-keys child device, replacing the old
> > platform_data mechanism.
>
> Thanks for doing this Dmitry! I believe I didn't understand how 
> providing the IRQs via swnode works... :)
>
> If I visit the ROHM office this week, then I will try to test this using 
> the PMIC HW. (Next week I'll be in ELCE, and after it I have probably 
> already forgotten this...)
>
> > The power key's properties are now defined using software nodes and
> > property entries. The IRQ is passed as a resource attached to the
> > platform device.
> >
> > This will allow dropping support for using platform data for configuring
> > gpio-keys in the future.
> >
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> > ---
> >   drivers/mfd/rohm-bd71828.c | 81 +++++++++++++++++++++++++++-----------
> >   1 file changed, 58 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/mfd/rohm-bd71828.c b/drivers/mfd/rohm-bd71828.c
> > index a14b7aa69c3c..c29dde9996b7 100644
> > --- a/drivers/mfd/rohm-bd71828.c
> > +++ b/drivers/mfd/rohm-bd71828.c
> > @@ -4,7 +4,6 @@
>
> // ...snip
>
> > +static int bd71828_reg_cnt;
> > +
> > +static int bd71828_i2c_register_swnodes(void)
> > +{
> > +    int error;
> > +
> > +    if (bd71828_reg_cnt == 0) {
>
> Isn't this check racy...
>
> > +        error = software_node_register_node_group(bd71828_swnodes);
> > +        if (error)
> > +            return error;
> > +    }
> > +
> > +    bd71828_reg_cnt++;
>
> ... with this...
>
> > +    return 0;
> > +}
> > +
> > +static void bd71828_i2c_unregister_swnodes(void *dummy)
> > +{
> > +    if (bd71828_reg_cnt != 0) {
>
> ...this...
>
> > +        software_node_unregister_node_group(bd71828_swnodes);
> > +        bd71828_reg_cnt--;
>
> ...and this? Perhaps add a mutex or use atomics?
>
> Also, shouldn't the software_node_unregister_node_group() be only called 
> for the last instance to exit (Eg, "if (bd71828_reg_cnt == 0)" instead 
> of the "if (bd71828_reg_cnt != 0) {")?

Oh. Probably "if (bd71828_reg_cnt == 1)".

> > +    }
> > +}
> > +
>
> Other than that - I like this idea :)
>
> Thanks!
>
> Yours,
>      -- Matti