linux-kernel - Re: [PATCH V6 2/2] irqchip/sifive-plic: Fixup thead,c900-plic dt parse in opensbi

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Message-ID: <87r18qxui9.wl-maz@kernel.org>
Date:   Sat, 29 Jan 2022 18:32:46 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     guoren@...nel.org
Cc:     anup@...infault.org, tglx@...utronix.de, palmer@...belt.com,
        samuel@...lland.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH V6 2/2] irqchip/sifive-plic: Fixup thead,c900-plic dt parse in opensbi

On Sat, 29 Jan 2022 16:27:26 +0000,
guoren@...nel.org wrote:
> 
> From: Guo Ren <guoren@...ux.alibaba.com>
> 
> The thead,c900-plic has been used in opensbi to distinguish
> PLIC [1]. Although PLICs have the same behaviors in Linux,
> they are different hardware with some custom initializing in
> firmware(opensbi).
> 
> [1]: https://github.com/riscv-software-src/opensbi/commit/78c2b19218bd62653b9fb31623a42ced45f38ea6
> 
> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> Cc: Anup Patel <anup@...infault.org>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Palmer Dabbelt <palmer@...belt.com>
> Cc: Samuel Holland <samuel@...lland.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> ---
>  drivers/irqchip/irq-sifive-plic.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 259065d271ef..245655928076 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -172,7 +172,7 @@ static void plic_irq_eoi(struct irq_data *d)
>  	}
>  }
>  
> -static struct irq_chip plic_chip = {
> +static struct irq_chip sifive_plic_chip = {
>  	.name		= "SiFive PLIC",
>  	.irq_mask	= plic_irq_mask,
>  	.irq_unmask	= plic_irq_unmask,
> @@ -182,12 +182,24 @@ static struct irq_chip plic_chip = {
>  #endif
>  };
>  
> +static struct irq_chip thead_plic_chip = {
> +	.name		= "T-Head PLIC",
> +	.irq_mask	= plic_irq_mask,
> +	.irq_unmask	= plic_irq_unmask,
> +	.irq_eoi	= plic_irq_eoi,
> +#ifdef CONFIG_SMP
> +	.irq_set_affinity = plic_set_affinity,
> +#endif
> +};

For pure entertainment, let's compare the two structures:

static struct irq_chip plic_chip = {
	.name		= "SiFive PLIC",
	.irq_mask	= plic_irq_mask,
	.irq_unmask	= plic_irq_unmask,
	.irq_eoi	= plic_irq_eoi,
#ifdef CONFIG_SMP
	.irq_set_affinity = plic_set_affinity,
#endif
};

Oh wait: a string. Must be really important. Not.

> +
> +static struct irq_chip *def_plic_chip = &sifive_plic_chip;
> +
>  static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
>  			      irq_hw_number_t hwirq)
>  {
>  	struct plic_priv *priv = d->host_data;
>  
> -	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
> +	irq_domain_set_info(d, irq, hwirq, def_plic_chip, d->host_data,
>  			    handle_fasteoi_irq, NULL, NULL);
>  	irq_set_noprobe(irq);
>  	irq_set_affinity(irq, &priv->lmask);
> @@ -396,5 +408,14 @@ static int __init plic_init(struct device_node *node,
>  	return error;
>  }
>  
> +static int __init thead_c900_plic_init(struct device_node *node,
> +		struct device_node *parent)
> +{
> +	def_plic_chip = &thead_plic_chip;
> +
> +	return plic_init(node, parent);
> +}
> +
>  IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
>  IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
> +IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", thead_c900_plic_init);

Sorry, but I can't see any point to this patch.

	M.

-- 
Without deviation from the norm, progress is not possible.