[PATCH 2/3] irqchip/gic-v3: Add Renesas R-Car Gen4 erratum workaround

[Geert Uytterhoeven]

Hi Marek,

On Wed, 17 Jun 2026 at 05:00, Marek Vasut
<marek.vasut+renesas at mailbox.org> wrote:
> Renesas R-Car S4/V4H/V4M GIC600 integration has address width for AXI
> or APB interface configured to 32 bit, it can therefore access only
> the first 4 GiB of physical address space. This information comes from
> R-Car V4H Interface Specification sheet, there is currently no technical
> update number assigned to this limitation. Further input from hardware
> engineer indicates that this limitation also applies to R-Car S4 and V4M.
> Name the limitation GEN4GICITS1, and add a driver quirk to mitigate this
> limitation.
>
> Note that the 0x0201743b GIC600 ID is not Renesas-specific, it is
> common for many ARM GICv3 implementations. Therefore, add an extra
> of_machine_is_compatible() check.
>
> The GIC600 implementation in R-Car S4/V4H/V4M is r1p6.
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh at renesas.com>
> Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>

Thanks for your patch!

> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -4901,6 +4901,18 @@ static bool __maybe_unused its_enable_rk3568002(void *data)
>         return true;
>  }
>
> +static bool __maybe_unused its_enable_renesas_gen4(void *data)
> +{
> +       if (!of_machine_is_compatible("renesas,r8a779f0") &&
> +           !of_machine_is_compatible("renesas,r8a779g0") &&
> +           !of_machine_is_compatible("renesas,r8a779h0"))

of_machine_compatible_match() with an array of strings might generate
smaller code (I didn't check if 3 entries is enough to trip the balance).

> +               return false;
> +
> +       gfp_flags_quirk |= GFP_DMA32;
> +
> +       return true;
> +}
> +
>  static const struct gic_quirk its_quirks[] = {
>  #ifdef CONFIG_CAVIUM_ERRATUM_22375
>         {

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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