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

From: Gavin Shan <[email-masked]>
Date: Wed, 6 Mar 2013 12:09:35 +0800

On Wed, Mar 06, 2013 at 02:24:54PM +1100, Michael Ellerman wrote:
>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.
>

Thanks, Michael. I neve know that you've implemented bitmaps to manage
MSI interrupts. It seems arch/powerpc/sysdev/msi_bitmap.c meets our
requirment here except that needs device tree node. Fortunately, we
can set the corresponding device tree node to NULL and functions playing
with the device tree nodes (of_node_get/of_node_put) works well for NULL
device tree node.

I'll update powernv platform to use msi_bitmap.c to manage it MSI interrupts.

Thanks,
Gavin