linux-kernel - Re: [PATCH] irqchip: riscv: Order normal writes and IPI writes

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Message-ID: <Z4l1fklnUPyTSLO4@ghost>
Date: Thu, 16 Jan 2025 13:09:18 -0800
From: Charlie Jenkins <charlie@...osinc.com>
To: Xu Lu <luxu.kernel@...edance.com>
Cc: anup@...infault.org, tglx@...utronix.de, paul.walmsley@...ive.com,
	palmer@...belt.com, lihangjing@...edance.com,
	xieyongji@...edance.com, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] irqchip: riscv: Order normal writes and IPI writes

On Thu, Jan 16, 2025 at 08:07:10PM +0800, Xu Lu wrote:
> Replace writel_relaxed() with writel() when issuing IPI to ensure all
> previous write operations made by current CPU are visible to other CPUs.

Did you experience an ordering issue from this?

- Charlie

> 
> Signed-off-by: Xu Lu <luxu.kernel@...edance.com>
> ---
>  drivers/irqchip/irq-riscv-imsic-early.c      | 2 +-
>  drivers/irqchip/irq-thead-c900-aclint-sswi.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-riscv-imsic-early.c b/drivers/irqchip/irq-riscv-imsic-early.c
> index c5c2e6929a2f..275df5005705 100644
> --- a/drivers/irqchip/irq-riscv-imsic-early.c
> +++ b/drivers/irqchip/irq-riscv-imsic-early.c
> @@ -27,7 +27,7 @@ static void imsic_ipi_send(unsigned int cpu)
>  {
>  	struct imsic_local_config *local = per_cpu_ptr(imsic->global.local, cpu);
>  
> -	writel_relaxed(IMSIC_IPI_ID, local->msi_va);
> +	writel(IMSIC_IPI_ID, local->msi_va);
>  }
>  
>  static void imsic_ipi_starting_cpu(void)
> diff --git a/drivers/irqchip/irq-thead-c900-aclint-sswi.c b/drivers/irqchip/irq-thead-c900-aclint-sswi.c
> index b0e366ade427..8ff6e7a1363b 100644
> --- a/drivers/irqchip/irq-thead-c900-aclint-sswi.c
> +++ b/drivers/irqchip/irq-thead-c900-aclint-sswi.c
> @@ -31,7 +31,7 @@ static DEFINE_PER_CPU(void __iomem *, sswi_cpu_regs);
>  
>  static void thead_aclint_sswi_ipi_send(unsigned int cpu)
>  {
> -	writel_relaxed(0x1, per_cpu(sswi_cpu_regs, cpu));
> +	writel(0x1, per_cpu(sswi_cpu_regs, cpu));
>  }
>  
>  static void thead_aclint_sswi_ipi_clear(void)
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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