[PATCH v7 21/24] mailbox/riscv-sbi-mpxy: Add ACPI support

[Anup Patel]

On Thu, Jul 3, 2025 at 7:24 PM Andy Shevchenko
<andriy.shevchenko at linux.intel.com> wrote:
>
> On Thu, Jul 03, 2025 at 04:24:18PM +0530, Sunil V L wrote:
> > On Wed, Jul 02, 2025 at 03:28:45PM +0300, Andy Shevchenko wrote:
> > > On Wed, Jul 02, 2025 at 10:43:42AM +0530, Anup Patel wrote:
>
> ...
>
> > > > -         if (dev_of_node(dev))
> > > > +         if (is_of_node(fwnode)) {
> > > >                   of_msi_configure(dev, dev_of_node(dev));
> > > > +         } else if (is_acpi_device_node(fwnode)) {
> > > > +                 msi_domain = irq_find_matching_fwnode(imsic_acpi_get_fwnode(dev),
> > > > +                                                       DOMAIN_BUS_PLATFORM_MSI);
> > > > +                 dev_set_msi_domain(dev, msi_domain);
> > > > +         }
> > >
> > > Actually you don't need to have the if-else-if if I am not mistaken.
> > > The OF does almost the same as it's done in the second branch for ACPI case.
> > > How many MSI parents this may have?
> > >
> > OF already has a well defined interface to configure the MSI domain. The
> > mechanisms existing today are different for DT vs ACPI to find out the
> > fwnode of the MSI controller. So, it is done differently.
>
> I don't see how. The only difference I see is that OF iterates over all listed
> parents, if any, ACPI tries only one.
>
> So, perhaps it's a time to have a common API somewhere for this to be agnostic?
> Something like fwnode_msi_configure() in somewhere of IRQ MSI core?
>

There is an issue/gap in the DD framework which is being work-around
here. This issue manifest mostly in RISC-V land because in RISC-V both
MSI controller driver and drivers using MSI are regular platform drivers
while the probe ordering is ensured by dev_link support of DD framework
or the frameworks (like ACPI) creating the device.

As-per this issue, when platform devices (DT or ACPI) are created the
MSI domain instance is not available and hence set to NULL. The MSI
domain instance is only available after MSI controller driver is probed
so currently we explicitly do of_msi_configure() or dev_set_msi_domain()
in the driver using MSI as a work-around. Adding a common
fwnode_msi_configure() is only going to be an improvement to the
existing work-around which we should not have in the first place
hence not the right approach IMO.

In the long run, we need a clean fix for the above issue in the DD
framework such that platform drivers using MSI don't have to explicitly
do of_msi_configure() or dev_set_msi_domain().

Regards,
Anup