Subject: Re: [PATCH] powerpc/powernv: Fix next available MSI IRQ

From: Michael Ellerman <[email-masked]>
Date: Wed, 6 Mar 2013 14:24:54 +1100

On Tue, Mar 05, 2013 at 02:59:16PM +0800, Gavin Shan wrote:
> The allocation of MSI is implemented based on bitmap and working
> like the mechanism of strict round through the traced next available
> cursor. However, the next available MSI is never updated in current
> implementation. The patch fixes the issue.
> 
> Signed-off-by: Gavin Shan <[email-masked]>
> ---
>  arch/powerpc/platforms/powernv/pci.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
> index 6f464dc..9cf18c4 100644
> --- a/arch/powerpc/platforms/powernv/pci.c
> +++ b/arch/powerpc/platforms/powernv/pci.c
> @@ -66,6 +66,11 @@ static unsigned int pnv_get_one_msi(struct pnv_phb *phb)
>  		rc = 0;
>  		goto out;
>  	}
> +
> +	if (id >= phb->msi_count - 1)
> +		phb->msi_next = 0;
> +	else
> +		phb->msi_next = id + 1;
>  	__set_bit(id, phb->msi_map);

There is code in arch/powerpc/sysdev/msi_bitmap.c that implements a
bitmap allocator for MSI. It may not do what you need but please take a
look at it if you haven't already.

cheers