Messages in this thread | | | Date | Fri, 22 Oct 2021 19:43:16 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH 09/15] irq: arm: perform irqentry in entry code |
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On Fri, 22 Oct 2021 18:58:54 +0100, Mark Rutland <mark.rutland@arm.com> wrote: > > On Fri, Oct 22, 2021 at 05:34:20PM +0100, Vladimir Murzin wrote: > > On 10/22/21 4:36 PM, Mark Rutland wrote: > > > On Fri, Oct 22, 2021 at 04:18:18PM +0100, Vladimir Murzin wrote: > > >> Hi Mark, > > >> > > >> On 10/21/21 7:02 PM, Mark Rutland wrote: > > >>> +/* > > >>> + * TODO: restructure the ARMv7M entry logic so that this entry logic can live > > >>> + * in arch code. > > >>> + */ > > >>> +asmlinkage void __exception_irq_entry > > >>> +static void nvic_handle_irq(irq_hw_number_t hwirq, struct pt_regs *regs) > > >> > > >> I'm seeing build time failure... > > >> > > >> drivers/irqchip/irq-nvic.c:50:8: error: two or more data types in declaration specifiers > > >> static void nvic_handle_irq(irq_hw_number_t hwirq, struct pt_regs *regs) > > >> ^~~~ > > >> drivers/irqchip/irq-nvic.c:50:13: warning: 'nvic_handle_irq' defined but not used [-Wunused-function] > > >> static void nvic_handle_irq(irq_hw_number_t hwirq, struct pt_regs *regs) > > >> > > >> I've fixed that locally and planing to give it a go... > > > > > > Ah, whoops. I've removed the extraneous `static void` from > > > nvic_handle_irq() and build tested that as part of stm32_defconfig. > > > > > > The updated version is in my irq/handle-domain-irq branch at: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git > > > > > > > $ cat /proc/interrupts > > CPU0 > > 16: 24 nvic_irq 4 Edge mps2-clkevt > > 17: 0 nvic_irq 32 Edge mps2-uart-rx > > 18: 6 nvic_irq 33 Edge mps2-uart-tx > > 19: 0 nvic_irq 47 Edge mps2-uart-overrun > > Err: 0 > > > > So if it helps feel free to add my > > > > Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M > > Thanks! > > I've folded that in and uppdated the branch. > > > As for TODO, is [1] look something you have been thinking of? IIUC, > > the show stopper is that hwirq is being passed from exception entry > > which retrieved via xPSR (IPSR to be precise). OTOH hwirq also available > > via Interrupt Controller Status Register (ICSR) thus can be used in > > driver itself... I gave [1] a go and it runs fine, yet I admit I might > > be missing something... > > I hadn't thought about it in much detail, but that looks good! > > I was wondering if we needed something like a > handle_arch_vectored_irq(), but if we can rely on the ICSR that seems > simpler overall. I'm not at all familiar with M-class, so I'm not sure > if there are pitfalls in this area.
Why can't we just use IPSR instead from the C code? It has the potential of being of lower latency then a MMIO read (though I have no idea whether it makes a material difference on M-class) and from what I can see in the arch spec, they are strictly equivalent.
Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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