[PATCH V2 2/6] powerpc/powernv: simplify the calculation of iov resource
aik at ozlabs.ru
Thu Aug 6 19:00:00 AEST 2015
On 08/06/2015 02:51 PM, Gavin Shan wrote:
> On Wed, Aug 05, 2015 at 09:24:59AM +0800, Wei Yang wrote:
>> The alignment of IOV BAR on PowerNV platform is the total size of the IOV
>> BAR. No matter whether the IOV BAR is truncated or not, the total size
>> could be calculated by (vfs_expanded * VF size).
> s/VF size/VF BAR size
> I think the changelog would be more explicit:
> The alignment of IOV BAR on PowerNV platform is the total size of the
> IOV BAR, no matter whether the IOV BAR is extended with number of max
> VFs or number of max PE number (256). The alignment can be calculated
> by (vfs_expaned * VF_BAR_size).
Is that really a PowerNV-specific requirement or it is valid for every
platform (I suspect this is the case here)?
Also, what is the exact meaning of "expanded" in @vfs_expanded? It is
either 255 (if individual VF BARs are <= 64MB) or
roundup_pow_of_two(total_vfs) (which is something like 4 or 16). What is
>> This patch simplifies the pnv_pci_iov_resource_alignment() by removing the
>> first case.
>> Signed-off-by: Wei Yang <weiyang at linux.vnet.ibm.com>
> Reviewed-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
>> arch/powerpc/platforms/powernv/pci-ioda.c | 14 +++++++++-----
>> 1 file changed, 9 insertions(+), 5 deletions(-)
>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>> index 9b41dba..7192e62 100644
>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>> @@ -2987,12 +2987,16 @@ static resource_size_t pnv_pci_iov_resource_alignment(struct pci_dev *pdev,
>> int resno)
>> struct pci_dn *pdn = pci_get_pdn(pdev);
>> - resource_size_t align, iov_align;
>> - iov_align = resource_size(&pdev->resource[resno]);
>> - if (iov_align)
>> - return iov_align;
>> + resource_size_t align;
>> + /*
>> + * On PowerNV platform, IOV BAR is mapped by M64 BAR to enable the
>> + * SR-IOV. While from hardware perspective, the range mapped by M64
>> + * BAR should be size aligned.
>> + *
>> + * This function return the total IOV BAR size if expanded or just the
>> + * individual size if not.
>> + */
>> align = pci_iov_resource_size(pdev, resno);
>> if (pdn->vfs_expanded)
>> return pdn->vfs_expanded * align;
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