Re: [PATCH v3 1/1] gpio: mpfs: add polarfire soc gpio support

Marc Zyngier
2022-07-16T17:52:37Z

On Sat, 16 Jul 2022 16:21:48 +0100,
<Lewis.Hanly@microchip.com> wrote:
>
> Thanks Marc,
>
> On Sat, 2022-07-16 at 11:33 +0100, Marc Zyngier wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you
> > know the content is safe
> >
> > On Sat, 16 Jul 2022 08:11:13 +0100,
> > <lewis.hanly@microchip.com> wrote:
> > > From: Lewis Hanly <lewis.hanly@microchip.com>
> > >
> > > Add a driver to support the Polarfire SoC gpio controller.
> > >
> > > Signed-off-by: Lewis Hanly <lewis.hanly@microchip.com>
> >
> > [...]
> >
> > > +static int mpfs_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
> > > + unsigned int child,
> > > + unsigned int child_type,
> > > + unsigned int *parent,
> > > + unsigned int *parent_type)
> > > +{
> > > + struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> > > + struct irq_data *d = irq_get_irq_data(mpfs_gpio-
> > > >irq_number[child]);
> >
> > This looks totally wrong. It means that you have already instantiated
> > part of the hierarchy, and it is likely that you will get multiple
> > hierarchy sharing some levels, which isn't intended.
>
> Some background why I use the above.
> We need to support both direct and non-direct IRQ connections to the
> PLIC.
> In direct mode the GPIO IRQ's are connected directly to the PLIC and
> certainly no need for the above. GPIO's can also be configured in non-
> direct, which means they use a shared IRQ, hence the above.

That's unfortunately not acceptable. You need to distinguish which one
is which, and separate them. Your non-direct mode certainly requires
special handling, and is not fit for a hierarchical mode.

M.

--
Without deviation from the norm, progress is not possible.