lkml.org 
[lkml]   [2022]   [Aug]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH 06/12] riscv: dts: allwinner: Add the D1 SoC base devicetree
    Hi Conor,

    On Mon, Aug 22, 2022 at 2:13 PM <Conor.Dooley@microchip.com> wrote:
    > On 22/08/2022 12:46, Geert Uytterhoeven wrote:
    > > On Sun, Aug 21, 2022 at 12:07 PM <Conor.Dooley@microchip.com> wrote:
    > >> On 21/08/2022 07:45, Icenowy Zheng wrote:
    > >>> 在 2022-08-20星期六的 17:29 +0000,Conor.Dooley@microchip.com写道:
    > >>>> On 20/08/2022 18:24, Samuel Holland wrote:
    >
    > >>>>> This is not feasible, due to the different #interrupt-cells. See
    > >>>>> https://lore.kernel.org/linux-riscv/CAMuHMdXHSMcrVOH+vcrdRRF+i2TkMcFisGxHMBPUEa8nTMFpzw@mail.gmail.com/
    > >>>>>
    > >>>>> Even if we share some file across architectures, you still have to
    > >>>>> update files
    > >>>>> in both places to get the interrupts properties correct.
    > >>>>>
    > >>>>> I get the desire to deduplicate things, but we already deal with
    > >>>>> updating the
    > >>>>> same/similar nodes across several SoCs, so that is nothing new. I
    > >>>>> think it would
    > >>>>> be more confusing/complicated to have all of the interrupts
    > >>>>> properties
    > >>>>> overridden in a separate file.
    > >>>>
    > >>>> Yeah, should maybe have circled back after that conversation, would
    > >>>> have been
    > >>>> nice but if the DTC can't do it nicely then w/e.
    > >>>
    > >>> Well, maybe we can overuse the facility of C preprocessor?
    > >>>
    > >>> e.g.
    > >>>
    > >>> ```
    > >>> // For ARM
    > >>> #define SOC_PERIPHERAL_IRQ(n) GIC_SPI n
    > >>> // For RISC-V
    > >>> #define SOC_PERIPHERAL_IRQ(n) n
    > >>> ```
    > >>>
    > >>
    > >> Geert pointed out that this is not possible (at least on the Renesas
    > >> stuff) because the GIC interrupt numbers are not the same as the
    > >> PLIC's & the DTC is not able to handle the addition:
    > >> https://lore.kernel.org/linux-riscv/CAMuHMdXHSMcrVOH+vcrdRRF+i2TkMcFisGxHMBPUEa8nTMFpzw@mail.gmail.com/
    > >
    > > Without the ability to do additions in DTC, we could e.g. list both
    > > interrupts in the macro, like:
    > >
    > > // For ARM
    > > #define SOC_PERIPHERAL_IRQ(na, nr) GIC_SPI na
    > > // For RISC-V
    > > #define SOC_PERIPHERAL_IRQ(na, nr) nr
    >
    > Do you think this is worth doing? Or are you just providing an
    > example of what could be done?

    Just some brainstorming...

    > Where would you envisage putting these macros? I forget the order
    > of the CPP operations that are done, can they be put in the dts?

    The SOC_PERIPHERAL_IRQ() macro should be defined in the
    ARM-based SoC.dtsi file and the RISC-V-based SoC.dtsi file.

    > > On Mon, Aug 22, 2022 at 12:52 PM Andre Przywara <andre.przywara@arm.com> wrote:
    > >> There are interrupt-maps for that:
    > >> sun8i-r528.dtsi:
    > >> soc {
    > >> #interrupt-cells = <1>;
    > >> interrupt-map = <0 18 &gic GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>,
    > >> <0 19 &gic GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>,
    > >> ....
    > >>
    > >> sun20i-d1.dtsi:
    > >> soc {
    > >> #interrupt-cells = <1>;
    > >> interrupt-map = <0 18 &plic 18 IRQ_TYPE_LEVEL_HIGH>,
    > >> <0 19 &plic 19 IRQ_TYPE_LEVEL_HIGH>,
    > >>
    > >> then, in the shared .dtsi:
    > >> uart0: serial@2500000 {
    > >> compatible = "snps,dw-apb-uart";
    > >> ...
    > >> interrupts = <18>;
    > >
    > > Nice! But it's gonna be a very large interrupt-map.
    >
    > I quite like the idea of not duplicating files across the archs
    > if it can be helped, but not at the expense of making them hard to
    > understand & I feel like unfortunately the large interrupt map is
    > in that territory.

    I feel the same.
    Even listing both interrupt numbers in SOC_PERIPHERAL_IRQ(na, nr)
    is a risk for making mistakes.

    So personally, I'm in favor of teaching dtc arithmetic, so we can
    handle the offset in SOC_PERIPHERAL_IRQ().

    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

    \
     
     \ /
      Last update: 2022-08-22 14:40    [W:2.355 / U:0.416 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site