linux-kernel - Re: [PATCH hyperv-next v5 11/11] PCI: hv: Get vPCI MSI IRQ domain from DeviceTree

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Message-ID: <20250310164122.GA551965@bhelgaas>
Date: Mon, 10 Mar 2025 11:41:22 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Roman Kisel <romank@...ux.microsoft.com>
Cc: arnd@...db.de, bhelgaas@...gle.com, bp@...en8.de,
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Subject: Re: [PATCH hyperv-next v5 11/11] PCI: hv: Get vPCI MSI IRQ domain
 from DeviceTree

On Fri, Mar 07, 2025 at 02:03:03PM -0800, Roman Kisel wrote:
> The hyperv-pci driver uses ACPI for MSI IRQ domain configuration on
> arm64. It won't be able to do that in the VTL mode where only DeviceTree
> can be used.
> 
> Update the hyperv-pci driver to get vPCI MSI IRQ domain in the DeviceTree
> case, too.
> 
> Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>

A couple minor comments below, but I don't have any objection to this,
so if it's OK with the pci-hyperv.c folks, it's OK with me.

> +#ifdef CONFIG_OF
> +
> +static struct irq_domain *hv_pci_of_irq_domain_parent(void)
> +{
> +	struct device_node *parent;
> +	struct irq_domain *domain;
> +
> +	parent = of_irq_find_parent(hv_get_vmbus_root_device()->of_node);
> +	domain = NULL;
> +	if (parent) {
> +		domain = irq_find_host(parent);
> +		of_node_put(parent);
> +	}
> +
> +	return domain;

I think this would be a little simpler as:

  parent = of_irq_find_parent(hv_get_vmbus_root_device()->of_node);
  if (!parent)
    return NULL;

  domain = irq_find_host(parent);
  of_node_put(parent);
  return domain;

> +}
> +
> +#endif
> +
> +#ifdef CONFIG_ACPI
> +
> +static struct irq_domain *hv_pci_acpi_irq_domain_parent(void)
> +{
> +	struct irq_domain *domain;
> +	acpi_gsi_domain_disp_fn gsi_domain_disp_fn;
> +
> +	if (acpi_irq_model != ACPI_IRQ_MODEL_GIC)
> +		return NULL;
> +	gsi_domain_disp_fn = acpi_get_gsi_dispatcher();
> +	if (!gsi_domain_disp_fn)
> +		return NULL;
> +	domain = irq_find_matching_fwnode(gsi_domain_disp_fn(0),
> +				     DOMAIN_BUS_ANY);
> +
> +	if (!domain)
> +		return NULL;
> +
> +	return domain;

  if (!domain)
    return NULL;

  return domain;

is the same as:

  return domain;

or even just:

  return irq_find_matching_fwnode(gsi_domain_disp_fn(0), DOMAIN_BUS_ANY);

> +}