Hi Geert,

On Mon, Dec 20, 2021 at 12:54 PM Geert Uytterhoeven
[off-list ref] wrote:

Hi Prabhakar,

On Mon, Dec 20, 2021 at 12:56 PM Lad, Prabhakar
[off-list ref] wrote:

quoted

On Mon, Dec 20, 2021 at 10:18 AM Geert Uytterhoeven
[off-list ref] wrote:

quoted

On Sat, Dec 18, 2021 at 5:59 PM Lad Prabhakar
[off-list ref] wrote:

quoted

platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
allocation of IRQ resources in DT core code, this causes an issue
when using hierarchical interrupt domains using "interrupts" property
in the node as this bypasses the hierarchical setup and messes up the
irq chaining.

Thanks for your patch!

quoted

In preparation for removal of static setup of IRQ resource from DT core
code use platform_get_irq_optional() for DT users only.

Why only for DT users?
Plenty of driver code shared by Renesas ARM (DT-based) on SuperH
(non-DT) SoCs already uses platform_get_irq_optional(), so I expect
that to work for both.

For the non DT users the IRQ resource is passed as a range [0] and not
a single interrupt so I went with this approach. Is there a way I'm
missing where we could still use platform_get_irq_xyz() variants for
such cases?

Oh, I didn't realize it used a single resource with a range.
Is this common, i.e. would it make sense to add support for this to
platform_get_irq_optional()?

No this isn't common even non dt users should ideally be passing a
single IRQ resource. There are very few such platforms which do this
so I don't see any point in adding this support to
platform_get_irq_optional() unless the IRQ maintainers think otherwise.

quoted

quoted

quoted

--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c

quoted

quoted

quoted

+                       if (irq <= 0 && irq != -ENXIO)
+                               return irq ? irq : -ENXIO;

Can irq == 0 really happen?

All SuperH users of the "i2c-sh_mobile" platform device use an
evt2irq() value that is non-zero.

I might have missed something, but it seems the only user of IRQ 0 on
SuperH is smsc911x Ethernet in arch/sh/boards/board-apsh4a3a.c and
arch/sh/boards/board-apsh4ad0a.c, which use evt2irq(0x200).

I'll keep that in mind if the Ethernet driver falls in the convection
patch changes.

The Ethernet driver was converted 6 years ago, cfr. commit
965b2aa78fbcb831 ("net/smsc911x: fix irq resource allocation failure").

Thanks for the pointer.

Cheers,
Prabhakar

quoted

[0] https://elixir.bootlin.com/linux/v5.16-rc6/source/arch/sh/kernel/cpu/sh4a/setup-sh7724.c#L454

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds