linux-kernel - Re: [PATCH 16/21] MSI: arch should connect the irq and the msi

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Date:	Wed, 28 Mar 2007 06:15:37 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Michael Ellerman <michael@...erman.id.au>
Cc:	linux-pci@...ey.karlin.mff.cuni.cz,
	Greg Kroah-Hartman <greg@...ah.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"David S. Miller" <davem@...emloft.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	<linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...l.org>,
	<daniel.e.wolstenholme@...el.com>
Subject: Re: [PATCH 16/21] MSI: arch should connect the irq and the msi_desc desc when it's ready

Michael Ellerman <michael@...erman.id.au> writes:

> set_irq_msi() currently connects an irq_desc to an msi_desc. The archs call
> it at some point in their setup routine, and then the generic code sets up the
> reverse mapping from the msi_desc back to the irq.
>
> set_irq_msi() should really do both connections, making it the one and only
> call required to connect an irq with it's MSI desc.

Hmm.  This comment should be a little more forceful than a suggestion
to make ti clear you have made that change somewhere in this
patch.

> It should be the arch code that calls set_irq_msi(), and it should do so
> only once it's sure it's not going to fail the irq allocation.
>
> Given that there's no need for the arch to return the irq anymore, the return
> value from the arch setup routine just becomes 0 for success and !0 for
> failure.

Call it negative for failure, or possibly nonzero.  !0 == 1  Which
isn't what you meant, and is confusing comparing it to the code.

Ok.  This is likely me limit of picking on your patches for tonight.



> Index: msi-new/arch/ia64/kernel/msi_ia64.c
> ===================================================================
> --- msi-new.orig/arch/ia64/kernel/msi_ia64.c
> +++ msi-new/arch/ia64/kernel/msi_ia64.c
> @@ -74,7 +74,6 @@ int ia64_setup_msi_irq(struct pci_dev *p
>  	if (irq < 0)
>  		return irq;
>  
> -	set_irq_msi(irq, desc);
>  	dest_phys_id = cpu_physical_id(first_cpu(cpu_online_map));
>  	vector = irq;
>  
> @@ -91,11 +90,13 @@ int ia64_setup_msi_irq(struct pci_dev *p
>  		MSI_DATA_DELIVERY_FIXED |
>  		MSI_DATA_VECTOR(vector);
>  
> +	desc->irq = irq;
Setting desc->irq just before set_irq_msi appears redundant here.
> +	set_irq_msi(irq, desc);
>  	set_irq_chip_and_handler(irq, &ia64_msi_chip, handle_edge_irq);
>  	get_irq_chip(irq)->mask(irq);
>  	write_msi_msg(irq, &msg);
>  
> -	return irq;
> +	return 0;
>  }
>  
>  void ia64_teardown_msi_irq(unsigned int irq)

Eric
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