[PATCH V6] irqchip/sifive-plic: Fixup EOI failed when masked

[Nikita Shubin]

On Mon,  1 Nov 2021 21:17:36 +0800
guoren at kernel.org wrote:

Hi Guo Ren,

Thank you for your patch.

May be it should be applied to stable ?

Tested-by: Nikita Shubin <nikita.shubin at maquefel.me>

> From: Guo Ren <guoren at linux.alibaba.com>
> 
> When using "devm_request_threaded_irq(,,,,IRQF_ONESHOT,,)" in the
> driver, only the first interrupt could be handled, and continue irq
> is blocked by hw. Because the riscv plic couldn't complete masked irq
> source which has been disabled in enable register. The bug was
> firstly reported in [1].
> 
> Here is the description of Interrupt Completion in PLIC spec [2]:
> 
> The PLIC signals it has completed executing an interrupt handler by
> writing the interrupt ID it received from the claim to the
> claim/complete register. The PLIC does not check whether the
> completion ID is the same as the last claim ID for that target. If
> the completion ID does not match an interrupt source that is
> currently enabled for the target, the ^^ ^^^^^^^^^ ^^^^^^^
> completion is silently ignored.
> 
> [1]
> http://lists.infradead.org/pipermail/linux-riscv/2021-July/007441.html
> [2]
> https://github.com/riscv/riscv-plic-spec/blob/8bc15a35d07c9edf7b5d23fec9728302595ffc4d/riscv-plic.adoc
> 
> Reported-by: Vincent Pelletier <plr.vincent at gmail.com>
> Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
> Cc: Anup Patel <anup at brainfault.org>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: Marc Zyngier <maz at kernel.org>
> Cc: Palmer Dabbelt <palmer at dabbelt.com>
> Cc: Atish Patra <atish.patra at wdc.com>
> Cc: Nikita Shubin <nikita.shubin at maquefel.me>
> Cc: incent Pelletier <plr.vincent at gmail.com>
> 
> ---
> 
> Changes since V6:
>  - Propagate to plic_irq_eoi for all riscv,plic by Nikita Shubin
>  - Remove thead related codes
> 
> Changes since V5:
>  - Move back to mask/unmask
>  - Fixup the problem in eoi callback
>  - Remove allwinner,sun20i-d1 IRQCHIP_DECLARE
>  - Rewrite comment log
> 
> Changes since V4:
>  - Update comment by Anup
> 
> Changes since V3:
>  - Rename "c9xx" to "c900"
>  - Add sifive_plic_chip and thead_plic_chip for difference
> 
> Changes since V2:
>  - Add a separate compatible string "thead,c9xx-plic"
>  - set irq_mask/unmask of "plic_chip" to NULL and point
>    irq_enable/disable of "plic_chip" to plic_irq_mask/unmask
>  - Add a detailed comment block in plic_init() about the
>    differences in Claim/Completion process of RISC-V PLIC and C9xx
>    PLIC.
> ---
>  drivers/irqchip/irq-sifive-plic.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/irqchip/irq-sifive-plic.c
> b/drivers/irqchip/irq-sifive-plic.c index cf74cfa82045..259065d271ef
> 100644 --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -163,7 +163,13 @@ static void plic_irq_eoi(struct irq_data *d)
>  {
>  	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
>  
> -	writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
> +	if (irqd_irq_masked(d)) {
> +		plic_irq_unmask(d);
> +		writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
> +		plic_irq_mask(d);
> +	} else {
> +		writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
> +	}
>  }
>  
>  static struct irq_chip plic_chip = {