linux-kernel - Re: [PATCH v13 07/13] irqchip/riscv-imsic: Add device MSI domain support for platform devices

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Message-ID: <875xyji7mc.ffs@tglx>
Date: Tue, 20 Feb 2024 14:32:27 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Anup Patel <apatel@...tanamicro.com>, Palmer Dabbelt
 <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, Rob
 Herring <robh+dt@...nel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@...aro.org>, Frank Rowand
 <frowand.list@...il.com>, Conor Dooley <conor+dt@...nel.org>
Cc: Marc Zyngier <maz@...nel.org>, Björn Töpel
 <bjorn@...nel.org>, Atish
 Patra <atishp@...shpatra.org>, Andrew Jones <ajones@...tanamicro.com>,
 Sunil V L <sunilvl@...tanamicro.com>, Saravana Kannan
 <saravanak@...gle.com>, Anup Patel <anup@...infault.org>,
 linux-riscv@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, Anup Patel
 <apatel@...tanamicro.com>
Subject: Re: [PATCH v13 07/13] irqchip/riscv-imsic: Add device MSI domain
 support for platform devices

On Tue, Feb 20 2024 at 11:37, Anup Patel wrote:
> +#ifdef CONFIG_SMP
> +static void imsic_msi_update_msg(struct irq_data *d, struct imsic_vector *vec)
> +{
> +	struct msi_msg msg[2] = { [1] = { }, };

That's a weird initializer and why do you need an array here?

       struct msi_msg msg = { };

Should be sufficient, no?

> +
> +	imsic_irq_compose_vector_msg(vec, msg);
> +	irq_data_get_irq_chip(d)->irq_write_msi_msg(d, msg);
> +}

> +static int imsic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
> +				  unsigned int nr_irqs, void *args)
> +{
> +	struct imsic_vector *vec;
> +
> +	/* Legacy-MSI or multi-MSI not supported yet. */

Coming back to my earlier question:

>> What's legacy MSI in that context?
>
> The legacy-MSI is the MSI support in PCI v2.2 where
> number of MSIs allocated by device were either 1, 2, 4,
> 8, 16, or 32 and the data written is <data_word> + <irqnum>.

You talk about PCI/MSI, where more than one vector is named
multi-MSI. Contrary to the modern v3.0 variant which is PCI/MSI-X.

So this should be "Multi-MSI is not supported yet", no?

> +	if (nr_irqs > 1)
> +		return -ENOTSUPP;
> +
> +	vec = imsic_vector_alloc(virq, cpu_online_mask);
> +	if (!vec)
> +		return -ENOSPC;
> +
> +	irq_domain_set_info(domain, virq, virq,
> +			    &imsic_irq_base_chip, vec,
> +			    handle_simple_irq, NULL, NULL);

Please utilize the 100 characters.

> +	irq_set_noprobe(virq);
> +	irq_set_affinity(virq, cpu_online_mask);
> +
> +	return 0;
> +}

Thanks,

        tglx